Selecting a Package for Graphics Presentation. An Overview Second Edition Octaber 1994 Preface Selecting graphics software to satisfy a particular presentational task can be a daunting business. The range of packages available, particularly on microcomputer systems, presents a potentially bewildering choice. The lack of any standard, de facto or otherwise, for presentation graphics means that it is not possible to decide easily whether or not a particular package will produce the sort of picture type that you require for your work. The package documentadon has to be examined and, often, experts in the use of the package consulted to determine if a particular type of diagram or image can be produced. Again, a package may produce the type of picture that you require, but may not be capable of outputting it to the sort of device that you wish to use. In general, a great deal of time and effort may have to be expended before you can be satisfied that a particular package will fulfill your needs. The purpose of this document is to help speed up the package selection process by disdlling the characterisdcs of graphics presentation requirements into a matlivc of facilides which can be interrogated to find a suitable candidate item ofxsoftware. The document also looks in some detail at the anatomy of various types of chart and provides examples of those charts in common use within the University for research or educadonal purposes. The reader can then make use of the old adage that a picture is worth a thousand words, by picking out the sort of chart or diagram of interest and then checking to see which of the software packages can be used to produce it. We intend to update this document every Autumn. This first edidon tends to concentrate on micro-based facilities, future editions will increase its range and scope. Meanwhile we would appreciate any feedback on this first edition, and suggestions for its improvement. If you would like to add a package to the matrix, please let us know (there is contact information at the end of this document) - and we will send you a template to fill in. This edition was developed with support from the Advisory Group on Computer Graphics (AGOCG), and the authors wish to acknowledge that support, along with that given by the EUCS Documentation Team. Special acknowledgements are also due Frances Provan and Gordon Smith for various matrix entries. Richard Bacon, Alex Nolan, Francis van Millingen October 1994 Copyright i) Computing Services, University of Edinburgh 1993,1994 This document is made available subject to the condition that it shall not, by way of trade or otherwise, be lent, resold, hired out or otherwise circulated without the permission of AGOCG and the University of Edinburgh except and in so far as it may be copied for use within UK higher education for the normal business of the organisation. Where any part of this document is included in another document due acknowledgement is required. The use of registered names, trademarks etc. in this material does not imply, even in the absence of a speciElc statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Overview Presentation Graphics TE GRAP~CS RLVOLUTION RIS1NG STANDARDS INCRLASING CHOICE 2 HOW TO USE THIS DOCUMENT 3 WHAT DO YOU WANT TO DRAW? USING YOUR PICTURLS GErTING OUTPUT EVALUATING A PACKAGE A QUICK OVERVIEW OF PACKAGES AN IN-DeprH VEW OF PACKAGES SUPPORT ARRANGEMENTS 3 TYPES OF CHART (A PICTURE GALLERY) 5 2D CHARTS 3.1 Scatter charts 3.2 Line charts 3.3 High-low charts 3.4 Bar/Columncharts 3.5 Piecharts 3.6 Histograrns 3.7 Areacharts 3.8 Bubblecharts 3.9 QC Charts 3.10 Polarcharts 3.11 Clusterchart 3.12 Vectorchart 3.13 Mixed charts 3.14 Organisationcharts 3.15 Text charts 3.16 2DContourcharts 3D CHARTS 3.17 3D Scatter 3.18 3D Grid or regular column chart 3.19 3DHistogram 10/11/94 Overview Presentation GraPhics 3.20 3D Surface charts 3.21 4D Contour charts 10 10 4 THE ANATOMY OF CHARTS AND DRAWINGS (THE PICTURE GALLERY EXTENDED) 11 CHARTS DRAWINGS ASPECTS OF DESIGN 1S 16 POPULAR FILE FORMATS BMP (Windows Bitmaps) CGM (Computer Graphics Metafile) GIF (Graphics Interchange Format) HPGL (Hewlett Packard Graphics Language) JPEG (Joint Photographic Experts Group) PICT ("QuickDraw Picture Format") EPS (Encapsulated PostScript) PCD (PhotoCD) PCX Sun Raster Files TIFF (Tag Image File Format) WMF (Windows Meta File) XWD (X-Windows Dump) GRAPHICS METAFILES CLIP ART 6 SELECTING AN OUTPUT DEVICE 21 FAITHFUL REPRODUCTION DEVICE CLASSIFICATION DEVICE ASSESSMENT TYPES OF DEVICE DOT-MATRIX PRINTERS LASER PRINTERS A4 Mono Laser printers Large Format Mono Laser printers Colour Laser printers PEN PU)IIERS ELECTROSTATIC PLOTTERS THERMAL TRANSFER PRINTERS INK JET PRIN rERs THERMAL DYE SUBLIMATION PRINTERS FILM RECORDERS UNSUPPORTED DEVICES ii 10/11/94 Overview Presentadon OnBphics 7 EXPLANATORY NOTES ON FACILITIES MATRIX 26 GENERAL INFORMATION MATRIX GENERAL Licence Arrangements Package Description Entries in Creative Graphics MatrLlc Entries in Data Driven Graphics Matrix SYSTEM ENVIRONMENT Platform Disk requirements Network version available USER ENVIRONMENT User interface On-line help OLE support FONTS Extra Fonts supplied with package Number IMPORT/EXPORT GRAPHICS FILE FORMATS File Type abbreviations OTHER FEATURES Slide show facilities Templates/Style sheets Clip Art Supplied Automatic backup facilities Pantone matching Extra Drivers with package DATA DRIVEN GRAPHICS FACILITIES MATRIX DATA HANDLING FACILI 1eS Editing facilities Calculation facilities Graph and data directly linked Statistical analysis Maximum number of variables Maximum number of data points Are missing values handled Data Interpolation 2-DIMENSIONAL DATA DISPLAY 3-DIMENSIONAL DATA DISPLAY OTHER DISPLAY OPTIONS Error-bars (X or Y) Curve fitting Plot Maths functions View Point adjustment Read Data points CHART AXES Axis Axis labeling iii 10/11/94 Overview Presentation GraPhics Tick Marks OTHER CHART FACILITES Titles Legends Data Point labels Floating labels (annotation) Chart size/position adjustment Background composition facilides Frame/bounding box Muldple charts on page CHART OBJECT ATTRIBUTES Number of line styles & widths Number of symbol styles Number of fill styles Size of pre-defined colour palette CREATIVE GRAPHICS FACILITIES CREATIVE DRAWING TOOLS Dynamic line width DRAWING ATTRIBUTES l,ayers Number of line styles & widths Number of fill styles Size of pre-defined colur palette SPECIAL EFFECTS Blend objects Contour objects Envelopes Extrude GLOSSARY 35 APPENDIX 1 42 APPENDIX 2 44 iv 10/11/94 Owrview Presentation Graphics nv v 'C~- This document is aimed at people who are reasonably at home using a computer, and who want to solve a particular graphics problem. It should also be useful for advisors and consultants who have to help other people solve graphics problems. The Graphics Revolutlon The last decade has seen the microcomputer move from a games machine to an essential tool for analysing data and presenting reports. For the same reasons - increasing power, lower cost, more software - the scientific workstation has become ever more widespread, and the advent of X Windows, the availability of relatively cheap graphics terminals, and the widespread availability of graphics terminal emulators for PCs, have also extended the range of functionality of mainframe graphics software.› In fact, there is now an embarrassment of riches in both hardware and software: things are changing so fast, particularly on microcomputers, that today's top-of-the-range offering is tomorrow's museum piece. The task of matching function and capability to requirement, however, changes little - and the purpose of this overview document is to aid both user and adviser in achieving a satisfactory balance of hardware and software on one hand with the {leRirf^A reRlllt snt1 ava hle reRources on the other. Rising Standards Our expectations have changed with the improvements in microcomputers, workstations and graphics software: we expect lectures and presentations to have machine-produced OHP material and handouts, and the production of colourful 35mm slides is not only simple, it is a growth industry. The essential elements of good design do not change much, however. The presence of a feature in a package does not mean that the feature must be used in every slide or overhead. Nor does good design imply good content - beautifully presented rubbish is still rubbish! Increasing Cholce It is increasingly common to find that graphics packages will read the formats of other packages, even those running on completely different machines. There are also conversion packages which allow common file formats to be exchanged between different machines. Word processing (WP) packages and Desk Top Publishing (DTP) packages are becoming more versatile in the graphics formats they accept, which may lead to a situation in which there are actually very few differences between packages in terms of their functions and the final choice comes down to personal preference. Such differences between individual preferences should not be ignored! The choice of output device is also growing, particularly for producing colour. 35mm slide production from computer packages is not now a luxury. Colour PostScript printers are now used for producing coloured OHP material, rather than plotters which are almost exclusively used in scientific and structural design and analysis applications. The interaction of 10/1 1/94 Overview Presenion Graphics computers and video film is becoming increasingly common, but we deliberately exclude video production in this edition. The methods of bringing data into charts have also widened, from the simple import of plain text files, through reading database formats, to the 'hot links' of, for example, 'Dynamic Data Exchange' (DDE) in Windows 3 or integral spreadsheets - in which a change in one document is automatically passed through to another. For some applicadons, an active link between data and graphics package is vital, especially where the same sort of chart will be drawn regularly. 2 10/11/94 Overview Presentation Oraphics The aim of this document is to help you to decide what type of picture you want to produce, then to find the most suitable package -given your general computing environment -with which to achieve it. The main part of the document diwusses the various types of picture, while the capabilities of several widely-available graphics packages are comprehensively summarised in the appendices. What do you want to draw? Chapter 3 starts with a Picture Gallery (Figure 1) showing the main features of the most commonly used charts. The term chart is used to define any drawing, graph, list of text or other presentation. A chart may exist on its own, or it may be combined with text, or it may be joined with other charts to form a continuous series or slideshow. You should be able to find any type of chart you want to produce in thts gallery. The rest of the chapter then describes each of the types of chart considered in this document: this should help you to confirm that you are using the right chart for your task Chapter 4 describes in words and pictures the components of each type of chart, defining the terms which are used later in this document and in a package's own documentation. You need to know precisely what you want to produce before you can tell if a particular package can produce it. Uslng your plctures Chapter S briefly explains some of the variousfile and i~?laBe formats used in graphics and how they may be exchanged between applications and documents. Getting output Chapter 6 discusses output devices. Printers and plotters have a significant effect on the quality of the result you finally obtain from any package. The brief descriptions given there should help you to choose the most suitable form of output for the document you are producing, and offers advice on buying a device. Evaluating a package Chapter 7 details all the facilities that were considered when examining each package and explains the terms in which graphics packages are evaluated. There is a glossary at the end of the document to explain some basic graphics jargon. Tables containing the evaluation results for each package appear in Appendix 2. A quick overview of packages Appendix 1 summarises classes of Package. It gives a somewhat subjective summary of the strengths and weaknesses of several commonly-available packages, so you can quickly get an idea of whether a particular package can produce a particular result. It could also be used to steer vou towards the Package(s) which can achieve a desired effect. Negative entries in the 3 10/11/94 Overview Presenxion araphics table do not necessarily mean that a package cannot perform a particular task: it might be possible to force a package to do something for which it was never intended, but the effort involved might be huge. It is important to use the right tool for a job if you can. Keep in mind that it is often possible to combine features of charts to achieve the desired results: for example, a graph from one package might be combined with a freehand drawing from a second package. This is a useful method of circumventing deficiencies m packages for presenting scientific results -where subscripts, superscripts and non-English characters are very important. An In-depth vlew of packages Appendix 2 presents The Facilities Matrix - the heart of this document. This matrix gives a comprehensive summan of the capabilities of each of the packages identified in Appendix 1. Such lists are, of course, often out of date almost as soon as they are written, and should be considered for guidance only. The manual for the latest version of a particular package should be consulted to check for changes. No indication is given regarding costs as these can vary from supplier to supplier, and a CHEST agreement or site licence can have a considerable effect an cnRtR. Support Arrangements Where any additional local support arrangements exist, they are contained in the Supplement attached to the end of the this document. 4 10/11/94 Overview Presentalion Graphics The pictorial representation of the types of chart types shown in Figure 1 are now described in greater detail in the rest of this chapter. 2D CHARTS 3.1 Scattercharts D . . . . ' .'~ ,t. This is the classic X vs Y' chart - indeed, some packages caH it X , , ,, ~,,,,<~ just that. Ideally suited for continuous variables in X and Y, it . ti^>.......usuaUy requires that a hne of best fit is drawn. GeneraUy this wB involve linear regression, but there might be cases when a spline or , . . . ~ * 1 ' quadradc funodon will be required. Will the constants of the fitted curve or line be available, and can they be added to the chart? 3,2 Line charts The line chart is a favourite of scientific workers. With date /< 2 variables, this sort of chart is particularly useful for showing o seasonal variadons. The line and scatter charts are related and / have many sitilar features - the line being a form of scatter chart 7 ttill~ 1~ 111@D 1~1 t~ 1tlZ in which the data points are connected, but a data marker is rarely shown. In the scatter chart, it is assumed that X and Y are continuous variables, while the X axis for a line chart may well be a discrete variable. It may be necessary to fit a curve or straight line through the data points, either to show a trend or to estimate a line of best-fit via regression to act as a standard curve. What level of complexity of curve-fitting will be required? Will statistics on the data (such as standard deviation, mean etc.) be required? Will correladon coefficients be required on lines? How many data series will be plotted? It is sensible to limit the amount of informadon contained in a chart, so that none of the informadon can be overlooked, and to avoid a cluttered presentadon. Two simple charts are better than one over-complicated one. Six data series should be regarded as a maximum. 3.3 High-lowcharts Stockbrokers and laboratory scientists both use charts which show an intermediate value between two extremes. This sort of presentadon is extremely important in medical and scientific work. Many packages which are designed for business use have high- low-close facilides which can be adapted to showing error bars, however some use terminators to the bar which do not fit in with scientific pracdce 6 10/11/94 Overview Presenxion (3raphics 3.4 Bar/Column charts e_- Bar charts are displayed horizontally across the chart, column charts are displayed vertically. The true bar chart is not often seen, but can be an excellent choice when the categories require complex naming. The paired bar chart is very effective in displaying the differences and similarities in two variables. Stacked bars are useful in certain circumstances, particularly if there is a danger of cluttering the chart, but can prove difficult to interpret. Once again, the most effecdve chart is one in which the amount of information is understandable and which does not overwhelm the viewer or reader. 3.5 Pie charts Conwny l_companv A The Pie chart is most effective when displaying up to six variables, ~r, but these can be augmented with linked pies and columns. The exploded segment is usefill for drawing attention to a particular cwyc segment, and can create striking visual effects. Many packages allow the data to be plotted as absolute values or as percentages of the total, and some have control over the orientation of the pie and the starting angle of the divisions. Multiple pie charts can be very effective. Oemmnv D~ 3.6 Histograms 3.7 Area charts 3.8 Bubble charts nx Confusingly, column charts are often referred to as bar charts. However histograms are a specific class of column chart associated with statistical work that calculates and displays the distribution of data in adiacent sinale columns of values On its own, dhe area chart is litde used: Perhaps that should be encouraged! It can fit in well with other charts, however, to form a mixed chart when two Y axes are used. The Bubble chart displays _n X, Y location together with the relative size of each item. It is frequendy used in market and product comparison studies 7 10/11/94 Overview Presentation Graphics 3.9 QC Charts The quality control chart is highly specialised, but very widely used. CuSum (cumulative sum) techniques are in use in manufacturing and analytical facilities worldwide - yet they are virtually unknown outside the QC laboratory. Some disciplines have other techniques which are in daily use. The simple example on the left shows the differences occurring between sampling subgroups in a large production run. Many of the highly specialised techniques, such as V-masks, are beyond the scope of general-purpose packages, although those who require such facilities may find that the literature on their subject contains references to how standard packages have been adapted to fft these requirements. a. .1J a.e 3.10 Polarcharts ';~ ~; A polar chart is one based on the polar coordinate system (as .~ ~,2 opposed to, for example, the Cartesian coordinate system). Each \~ a: ~; 2 } data point is defined in terms of a coordinate pair (r, theta); r is X 2 >, the distance from the centre of a circle (usually the origin of the ' s polar graph), and theta is the relative angle from a speciffed reference vector based at the centre of the same circle and extending to the "3 o'clock position" on the circle. 3.11 Clusterchart The term 'cluster' has been coined especially for this document This form of data presentation is extremely common in certain disciplines. It defies many tenets of graph drawing, but it offers a useful visual method of imparting inforrnation. The most common application is the situation of low, noImal and high values; for example, the levels of TSH in subjects whose levels of thyroxin are too high, too low or normal. This representation is common where the levels of an analyte are too low to be measured accurately, or too high for the exact concentration to be relevant and results are quoted as 'greater than some level'. Results are clustered together with the X-axis being descriptive rather than numeric. This sort of chart is often seen in medical and biological work, but the facility is not offered by many packages. The requirement for this sort of presentation should always be discussed early in an analysis of requirements: it cuts down the choice of packages dramatically and can save a lot of timel ._ . ~ v : ^ . _ a * }' ~ w r ~ w . w . 8 lO/ll/94 Overview Presentation GraDhics 3.12 Vectorchart 3 Mixed chsrh A vector chart is used to display the location, direction and magnitude of XY data pairs There are times when it is sensible to represent one set of data in one-way and another set in a different way, especially when a second Y-axis is used. This feature has generally been difficult to find in the graphical parts of spreadsheets and should be investigated early in the analysis of requirements. It is an effective tool in the right circumstances, but should not be overused. 3.14 Orzanisation charts 3.1S Text charts EuRO-FlfrURES PRESENTATION 3 Allgus 3.16 2D Contour charts Organisation charts are useful for displaying management structures. The number of levels required must always be defined. The text chart is perhaps the most widely used chart of alL Important limitations may cover subscripts and superscripts, foreign characters, chemical symbols and mathematical symbols. The most basic word processor can generally be of some use, although an early definition of the requirements for coloured text, gradient-filled backgrounds, imported bitmaps etc. will ascertain whether a word processor or a sophisticated presentation package will be needed. There is now considerable overlap in the facilities offered by word-processing, desktop publishing and presentation packages; the deciding factor maybe one of the choice and availability of output devices, or it may depend simply on personal preference and familiarity. In any event, it is essential that the package has all the facilities required; some DTP packages, for example, have very poor drawing facilities, while some modern WP packages have quite sophisticated drawing facilities. For the purposes of this document, text is considered to be a special case of graphics data. ~ ...... . ~)Su~ It is often necessary to be able to represent certain data as a2 ~ H & dimensional surface in 3-dimensional space. In general, we wish _ X > ; to plot a function of the form z=f(x,y), where, typically, the x and 7 -Xv ( .- - y values represent the 2-D location of a point, and z represents the variable to be visualised. One method is to make use of contour lines, as in, for example, an Ordnance Survey contour map. In the case of a relief map, the 9 l0/l l/94 Overview Presentation GraPhics alftude at points within the area represented by the map is the funcdon concerned, and the grid reference coordinates of these points are the independent variables. Data visualised via contouring are typically measurements of the height of a pardoular landscape, but in fact, anything which is a function of two independent variables, and which can be measured in some sense, can be visualised via contouxing. 3D CHARTS 3.17 3D Scatter Similar to 2D scatter charts, except that the addidon of a third Z co-ordinate allows the data to be represented in 3 dimensional space. 3.18 3D Grid or regular column chart 3.19 3D Histogram 3.20 3D Surface charts . . 3.21 4D Contour charts A grid chart is effectively a 3 dimensional column chart of regular data Many packages give support for converting irregularly space data to this regular grid form for analysis. Similar to 2D histogram except that it calculates and displays the distnbution of X-Y pairs from two columns of data thereby giving a 3D distribution of data pairs. It may also be considered a special form of 3D grid. A 3D surface plot graphs a matrix of X,Y and Z values as a 3 dimensional; grid or mesh. The is a combination of laying a contour plot over a 3D surface plot. 10 10/11/94 Overview Presentation Graphics Figure 1 in Chapter 3 gave a pictorial representation of the types of chart. We shall look at the general features of each type and describe many of the terms used in the facilities matrix (see Appendix 2) Next, we examine the details of charts and the terminology involved, The term 'data series' is used to describe a group of numbers or measurements which refer to one variable. Some packages limit the amount of data in any one series, while keeping the total amount of data constant; others set an upper limit on the number of data series while allowing each series to contain large amounts of data. These constraints are often very important in the choice of package appropriate to the analysis and presentation of the data. Always bear in mind that a chart can become overcrowded and unintelligible if there are too many data series, so some of these constraints may be beneficial. Charts We cannot cover every possible chart or pictorial representation as each discipline has its own specialities, but the facilities offered by packages continue to develop and expand. If a particular feature is not available today, check again in six months time - a new product may be available or the facilities offered by existing packages may have changed. The Anatomy of a Chart| [ Title Isubtitlel frame leoond Figure 2: The anatomy of a chart bounding bo kfala value r~,ata point otror bars 56 <(vr rtical and horkontal} ;'f symbol types line typas 11 10/11/94 Overview Presonxion GraPhics The title and subtitle, and perhaps the footnote, are common to many types of .chart. Sometimes dhey are identiEled specifically and sometimes they are added as separate text, not identified specially. The tide and subtitle give the audience an important 'handle' on the message and draw attention to what is being said. Sometimes they emphasise the speaker's identity or affiliation. The footnote is useful in organising charts. The legend explains what each series of data represents. Different line types are required for black and white output, while different colours can be used to distinguish the different data series if colour output devices are available P but bear in mind that colour vision is impaired in a significant number of people, and also that certain colours do not stand out in poor lightning conditions. In some circumstances it can be valuable to give dhe exact value of a data point, while in others, overall trends are all that is required. 'Missing data' are always a problem. If a data series is likely to be incomplete, how does a package respond? Does it simply skip over the blank or does it interpret absence as zero? Can missing data be coded so dhat the package knows to skip over the value? Will the package expect a full data series for each variable in a group? Many series of data contain outliers or extreme values which distort the presentation: will logarithmic axes be necessary? If so, how will the package represent a zero value? Can the axes be sPlit to avoid large areas of emptv space? | The anatomy of axesl Y-maximumA 11 O- tichs (extsrnalF~~ e40 Y-axis labels>30 Figure 3: T)1e anatomy of axes f tlcks (internal and external) tiCkY (Int@rnal) Sb breah . . urld Y-minimum H ø O ~> ~'X' zSg9_ 23~ X-minimum division division | X-&xi3 title | Axis labels X-maximum Examination of papers in scientific journals will show that there is a wide variety of methods for presenting axes: does the target journal have a specific style? Will separated axes be necessary? How many major divisions are appropriate for the data and what is the best number to choose to enhance the message without cluttering the display? Can the maximum 12 10/11/94 Overview Presentation Graphics and minimum values for the axes be defined? Are subdivisions really necessary or will it be best to give exact data values? Will the placing of the axes' tick marks be important? What sort of X-data will be employed? Textual, numeric or date? If a time series is required, what is thc best way to show the divisions? How will the axes be labelled? Will scientific notation, subscripts, superscripts and non-English characters be necessary? If so, can the printer produce the full range? Is the orientation of the Y-axis label important? Can it be aligned vertically? How many X and Y axes are needed and how many are optimal to present the data, but to avoid over- crowding the image by presenting too much data? Will contours and Z axes be necessary? Anatomy of bar/oolumn ohart~ l l | Paired bar | drsp; V V 100% overlap width=100 width=50 ovorlap(S0%) 3D effectwlth 3D rR cl Stachzed Stack@d (100%) Figure 4: The anatomy of bar and column charts The line or scatter graph is very widely used for presenting scientific data, while bar and column charts are often used for showing differences between discrete variables. Many of the ideas introduced here can be applied to other types of chart. The width can be varied so that columns touch, as they do with histograms, or points can be emphasised by keeping the columns separate. The display can be made less cluttered by overlapping the columns or by stacking the data. Percentages can be emphasised by employing the stacked column (100%) technique and some pleasing results can be obtained by adding 3D effects. The combination of 3D effects and overlapping can, in certain circumstances, hide data if a tall column comes in front of a short column; in this case it may be possible to change the angle of vision by rotating the chart. If this proves necessary, is the choice of chart type appropriate? The paired bar chart is often good at showing differences between two categories, such as the comparative performance of two cars over a number of criteria. The choice of fill pattern can also be important P solid colour can be easier to distinguish than similar patterns, particularly if there is unfortunate juxtaposition of small data sets. 13 10/11/94 Overview Presentabon GraDhics scgmert valuc 7 ~g srjgmcnt percrint > 43%(~ 23% pla chan with onc cxplodad sogmcnt 3d plo chan llnked3-D pb chart wlth onrs column cxplodcd sCDm@nt Fieure 5: The anatomv of a Pie chart pb ehart Wlth multipb cxploded scDmcntr~ 3-D pb chan wnh multipic cxplod@d sr DmcNts A Pie-chart is a popular and useful way of representing small numbers of variables. Particular aspects can be emphasised by exploding segments. Some packages are poor at exploding 3D pie charts. Will it be necessary to show data values, or percentages of the total? If there is an aggregated group ('other'), will it be useful to have a linked pie or column chart giving a detailed analysis? The pie chart is ideally suited to small numbers of variables, so the number of fill patterns or colours available will rarely be an issue, although the appropriate choice of pattern or colour will be important. Anatomy of a Polar Chart In generol, the polnt (r. theta) isata distance r from some flxed reference point and at an angle theta from the horMontal through the reference point. lAO 160 210 120 20-10-0-10-20 240 270 300 data point at (15.60) i.e. at a distance 15 units from the centre. and at an angle of 60 dearees from the hortontal data point (20,45) i.e. at a 330 distonce 20 units from the centre and at an angle 45 ees from the 14 10/11/94 Overview Presentation Graphics Figure 6: The anatomy of a Polar Chart Polar charts are used in science and engineering in applications where it is more natural to express coordinates in polar than in cartesian form. Drawings Figures 7 and 8 show some of the tools a skilled artist can use for eye-catching effects. Rotation, skewing and mirroring are available in most drawing packages, but the power of control point adjustment, perspective adjustment and 'enveloping' are confined to specialist programs. In particular, control point adjustment gives incredible power over positioning and the shape of curves. These techniques can be combined with the ability to fill objects with different patterns and colours to create images which are attractive, as well as informative. -1-o Mirror Shrsw rosizr~ object Figure 7: some features offreehand drawing ~ C Rotation Flip varlically Fllp horizontally 15 lO/11/94 Overview Presentation Graphics oredbnt Perspsuctiv~ Adlustment eontrol polntHnehor polnt FiRure 8: more features of freehand drawinR Aspects of Design ................. .. Control polnt adlustmont Envolopo The issue of picture design is a potendally complex one which raises many questions, such as: Typefaces What sort of font (bold, italic, etc.) should be used? how many different typefaces should be used within any one picture/ What size of typeface would look best? Layout Where should the various components of a picture be placed in relation to one another? What relative size should each picture component be? What effects can be employed to draw attention to one particular aspect of a picture? Colour Which colour combinations go well together? Which combinations should be avoided? which combinations should be used to compensate for colour blindness? Should colour be used at all? Would black and white (or some form of grey scale) be more effective in particular circumstances? If users are uncertain about these or any other aspects of design, professional advise should be sought. Refer to the supplement for references to any such bodies within your organisation. On the specific issue of colour in computer graphics, there are numerous publications. Some very useful introductory articles/booklets for anyone interested in learning more about colour usage are:  Using Colour in Computer Graphics, F.R.A. Hopgood, published by the Advisory Group on Computer Graphics, Technical Report No 4, January 1991.  Picture Perfect: Color Output for Computer Graphics, J. Rowell, published by Tektronix Inc, 1990. 16 10/11/94 Overview Plesentakton Graphics eradiont @ perspecti Adlustmont control polnt~2nehor polnt FiRure 8: rnore features of freehand drawing Aspects of Design ................. .. Control polnt adlustmrBnt Envelopo The issue of picture design is a potentially complex one which raises many questions, such as: Typefaces What sort of font (bold, italic, etc.) should be used? how many different typefaces should be used within any one picture/ What size of typeface would look best? Layout Where should the various components of a picture be placed in relation to one another? What relative size should each picture component be? What effects can be employed to draw attention to one particular aspect of a picture? Colour Which colour combinations go well together? Which combinations should be avoided? which combinations should be used to compensate for colour blindness? Should colour be used at all? Would black and white (or some form of grey scale) be more effective in particular circumstances? If users are uncertain about these or any other aspects of design, professional advise should be sought. Refer to the supplement for references to any such bodies within your organisation. On the specific issue of colour in computer graphics, there are numerous publications. Some very useful introductory articles/booklets for anyone interested in learning more about colour usage are:  Using Colour in Computer Graphics, F.R.A. Hopgood, published by the Advisory Group on Computer Graphics, Technical Report No 4, January 1991.  Picture Perfect: Color Outputfor Computer Graphics, J. Rowell, published by Tektronix Inc, 1990. 16 10/11/94 Overview Presentation Graphics  The Effective Use of Color, G. Murch, Tektronix Inc, Tekniques Newsletter, Vol 7 No 4, Winter 1983, Vol 8 No 1, Spring 1984, Vol 8 No 2, Summer 1984. The specific topic of colour blindness, and how to produce pictures which compensate for it, is covered in:  Computer Graphics: Principles and Practice, Foley, van Dam et al, Second edition, 1990, Addison-Wesley. Local advice and access to reference documentation may be available locally - refer to the Supple nent at the end of this document 17 10/11/94 Overview Presentation Graphics When preparing a document there are a number of sources from which images may be obtained. You may produce them yourself using a Drawing or Charting package or you may obtain them 'already drawn' as Clipart. In either case the image will probably be stored at some point in a file. If you produce them yourself you need only select a suitable exchange format which is common to the export~/import facilities of the packages concerned. Alternatively it may be possible to bypass the file stage completely by the use of the 'Cut and Paste' facilities. If you use Clipart, it usually supplied in the native image format used by that particular package. Often a package will also support other than it's own native format, so a wide variety of clipart may be available to you. Popular file formats There are a large number of different formats for storing graphics information in files. this list below only enumerates some of the more popular ones that are supported by the leading software packages. For more information you are recommended to consult either Graphics File Formats by Davis C. Kay and John R. Levine (Windorest/McOraw-Hill, 1992) or Encyclopedia of Graphics File Formats by (O'Reilly dc Associates, 1994) BMP (Windows Bitmaps) This is ideal for exchanging bitmap data between Windows applications, but is not widely available outside Windows. CGM (Computer Graphics Metafile) The CGM is an ISO standard for capturing and transfernng picture information. "Computer Graphics Metafile'' This is the first of ficial standard for graphics files and should be a reliable solution for the storage and exchange of graphics files - but it is large and unwieldy, and different implementations are not always mutually compatible. GIF (Graphics Interchange Format) Bitmap format developed by Compusewe. Good for cross-platform file exchange. Widely used, fUe compression means smaller storage requirements. HPGL (Hewlett Packard Graphics Language) A line based vector format originally developed for driving HP plotters, and available on some non pen plotter devices such as laser printers. It may also be used for transferring line-based information between applications JPEG (Joint Photographic Experts Group) JPEG is a standard format developed by the Joint Photographers Experts Groupw allowing transfer of files between a wide variety of platforms, using superior compression techniques. PICT ('6OuickDraw Picture Format") 18 10/1 1/94 Ovennew Presentation GraPhics This is a vector and bitmap page description language originating on the Mac. It is one of the commonest graphics standards on the Mac where it is very useful for exchanging both vector and bitmap data, but its colour support is limited, and it can only compress monochrome bitmap images. Versions of PICT are beginning to appear on PCs. EPS (Encapsulated PostScript) Postscript is a page descripdon language for both vector and bitmap graphics, which has become a de facto standard (see secdon 6.1 on page 28). It was originally intended for driving output devices such as pnnters, but is now widely used for storing and exchanging graphics images - for which it should be used in its "encapsulated" form EPS ("raw" PostScript can disrupt a document if it is inserted into it, rather than being sent straight to a printer). PostScript produces very portable plain text files, but these can become large and unwieldy for bitmap images. It has become a standard for desktop publishing. PCD (PhotoCD) This is storage format developed by Kodak for the storage of bitmap images PCX Also known as PC Paintbrush, this is a Wtmap format for desktop publishing, general graphics, and video. It is particularly useful for exchanging data between PCs. It is one of the oldest, and therefore most widely established, bitmap formats for PCs, supporting colour and large images, but some implementations may not be mutually compatible. Sun Raster Files This are bitmap format. Widely supported by Sun utilides and applications TIFF (Tag Image File Format) This is a bitrnap format for exchanging data between desktop applications, and available on Macs, PCs and Unix workstations. It is widely available, flexible and well-supported, and is excellent for storage, but non-standard extensions to the basic TisiF format mean that exchanging graphics between different platforms can sometimes fail. WMF (Windows Meta File) WMF files are useful for storing and exchanging graphics images under the Windows operating system, producing small, well-structured, device-independent files. It supports both bitmap and vector format. XWD (X-Windows Dump) This is a bitmap format. It is a useful method of exchanging bitmap based graphics between most X-Windows applications. Graphics Metafiles A Graphics Metafile is a file which contains a description of a picture (or set of pictures) expressed in some well-defined, fonnal manner. Graphics metafiles help to provide device independence by allowing pictures to be printed on a variety of devices; metafiles also facilitate picture portability by enabling the image(s) to be transferred to wherever they are required The ISO standard metafile is the 'Computer Graphics Metafile' (CGM). There are also proprietary standards such as the Microsoft Windows MetaFile (WMF) and the Macintosh PICT file - these are particularly useful for transferring images between applications in the same operating system, although it is often possible to use, say a PICI, file in a Windows environment. CGM, where supported, allow transfers of information between all systems. 19 lO/ll/94 Overview PresenXion Graphics Apart from the above three graphics metafiles, there are numerous other graphics file formats in use, particularly on microcomputer software. These other graphics file formats tend to be used both for the compression of picture data and for the interchange of picture informadon between software packages, What usually happens is thit the package exports the picture in a particular format which is then imported in that format by another package. The list of file formats available is extensive: the commonest are summarised in chapter 5. Additionally the matrix in Appendix 2 shows which files are interchangeable between chosen packages via the import/export mechanism. Clip AN The term 'clip-art' applies generally to any collection of computer-based images or symbols which can be readily incorporated within a user's picture. Most popular presentation graphics packages now include clip-art libraries covering a wide range of subjects. The idea is that the user's picture can be enhanced by the judicious use of particular images. For example, a chart which shows motor car production in the UK may be improved by including an image of a motor car. A clip-art library will typically contain aZset of images of everyday objects such as space rockets, telephones, washing machines, houses, furniture, airplanes, books, thermometers, ... indeed just about most things imaginable. Exactly how clip-art images are included within a user picture varies from package to package, but it is usually a straightforward process, and - again depending on the package - it is usually possible to expand, shrink or rotate the clip-art symbol so that it can be integrated within the picture to suit the user's requirements. Note! Users should take care that they do not inadvertently infringe copyright restrictions by including images within their pictures, such as for example company trademarks or logos, which may require copyright permission. 20 10/11/94 av-^.w Plesentation GraDhics .... ..... We look in this section at the various options available when printing graphics images on hardcopy devices (that is, devices which can print graphics images on various types of paper, transparencies, 35mm slides, video, and so on). We do not delve deeply into the detailed mechanisms which produce the hardcopy, rather we examine the available options at a level sufficient to enable the user to make sensible judgements about the sort of output device to use. For readers interested in knowing more about how hardcopy graphics images are produced, there is an introductory overview of colour output device technology in the Tektronix booklet Picture Perfiect, referenced at the end of chapter 4; for more detailed information about all types of hardcopy devices, the book Output Hardcopy Devices by Durbeck and Sherr (Academic Press, 1988) provides a wide-ranging set of articles about printer technology; the textbook Computer Graphics: Principles and Practice, referenced in chapter 4, also has a section on hardcopy technologies. Readers who want to know more about what colour printer options are currently available should look at Roy Middleton's Colour Printer Review (AGOCG/EUCS, September 1992). For general advice about graphics printers locally refer to the supplement about local arrangements at the end of this document. The images that you create on your computer display are virtually certain nowadays to be based on raster technology. However, when you want to produce a hardcopy version of a particular screen-based image, there is a considerable range of potential output devices for you to choose from. The range of equipment available can be bewildering, and the cost of producing a hardcopy picture varies considerably depending on the particular print technology employed, so it is important to decide on the sort of hardcopy that you require in advance of any production runs. Generally speaking, graphics packages have to support a very wide range of output devices. The way in which they do this, usually, is to provide a special piece of code, called a device driver, for each output device supported. Whenever the need arises to produce output on a particular device, the appropriate device driver is selected. (Note: systems, such as Microsoft Windows and Macintosh, come complete with a set of device drivers which can be selected by the graphics package rather than the package itself having to provide the device driver). Faithful reproduction A particularly important point to note at the outset when choosing an output device is that it is difficult, indeed impossible in most cases, to produce exactly the same image on some hardcopy device as the one you have produced on your computer display. This is particularly true where colour images are involved since it is notoriously difficult to produce the same colour on two different types of output device (see, for example, Hopgood' s technical report, as referenced in the section Aspects of Design of the previous chapter). The basic reason for this difficulty is that different output device types employ different underlying technologies. 21 10/1 1D4 Overview Presentation Graphics Other important points to bear in mind are: Cost (both the initial capital cost and the annual maintenance cost of the output device itself) Cost of each print Resolution (dots per inch) Output Quality Range of Colours Handled Media Size Handled (A4, A3, etc) Type of output (paper, OHPs, 35mm slides, video, etc) Device Classification Before looking at these aspects, it is useful to classify output devices in some way. One way is to group them into impact versus non-impact, an~ vector versus raster. Impact devices rely on the use of force to transfer dyes from a ribbon to paper or transparency. Typewriters, daisywheel printers and dot-matrix printers are examples of impact devices. Non-impact devices make no use of force to transfer the colour. Inkjet, thermal-wax transfer and laser printers are examples of non-impact devices. Vector devices typically use pens to draw lines ('vectors') on the paper or transparency. Pen plotters are the commonest example of a vector device. Raster devices make use of a regular matrix or grid containing thousands of tiny dots (which can be switched on or off, or otherwise coloured in some way) to form the image. Inkjet, laser, and thermal-wax transfer printers, and 35mm slide devices are examples of raster output devices. Vector devices are generally good at producing high line quality, but raster printers are much more effective at producing filled areas of colour and varied colour shading. Most high- quality computer graphics printers are nowadays non-impact, raster devices. Device Assessment Returning to the matters of cost, resolution, quality, etc, which were noted above: If cost is an issue, then both the initial cost of procuring an output device (along with maintenance costs) and the cost of producing hardcopy from the device must be taken into account. It may be that a suitable output device is already available, either on a networked basis, or within your department or some other department. It is therefore important, once you have decided on the sort of hardcopy output that you require, to find out if the sort of device needed is already available to you within your organisation. (The types of graphical output device available locally may be summarised in the Supplement at the end of this document) The issue of output quality is tied up with a number of factors. Firstly, the device resolution - or addressability - which is typically measured in dots-per-inch (dpi), should normally be 300 dpi and above to qualify as being of medium to high quality. However, colour can also play an important part in determining image quality, and it is possible to achieve impressive hardcopy images on relatively low resolution devices which have a large range of colours. Another critical factor in the quality equation is that of dot size. A high dpi resolution will only be really effective if the printer can also produce a small dot size. Equally, the 22 10/11/94 Overview Presentation Graphics consistency of the size, shape, and density of the dots, and the accuracy with which they are positioned on the output medium, all contribute to the overall quality of the final image. Finally, it is important to decide on the actual size of picture required. Large images (beyond A3 size) are generally only handled by the so-called electrostatic output devices or larger pen Dlotters, Types of Device Let us now take a look at the most commonly encountered types of output device and note some relevant facts about each: Dot-matrix prlnters These are low cost devices in the impact category which rely on the use of small wires in the print-head to transfer ink from a ribbon on to paper. Consumable costs are cheap, but the devices are typically noisy because of the use of impact technology. Speed, resolution and colour quality are generally poor, but nonetheless, dot-matrix printers are often satisfactory for drafts or in-house presentations. -~ser printers A4 Mono Laser printers Nowadays this is without doubt the workhorse of the hardcopy business, generally replacing the impact printers in the office and relieving the load on pen plotters. It produces good quality paper and OHP transparency output at 300 dpi, reliably and at a reasonable speed, with cost per copy merely a few pence. Being a raster device it can integrate text (permitting many typefaces) with graphics and raster images. A variety of models exist with facilities to accept PostScript or HPGL. Some models emulate the HP Laserjet, a very popular printer from Hewlett-Packard. HPGL emulation is useful to enable laser printer output to be obtained from software that otherwise would only output to a pen plotter. PostScript printers tend to be more expensive than Laserjet types, but offer greater versatility and are effectively a de facto standard. Extra memory is usually required for graphics applications. Software PostScript interpreters may also be deployed to allow .PostScript files to be printed on non-PostScript printers. Capital cost ranges from less than œ1,000 upwards. Large Format Mono Laser printers A variety of models exist with facilities to accept PostScript or HPGL. The capital cost is very high (œ50,000 plus), and the consumable cost varies from around œ1 (for in-house use) up to œ10 (commercial use). Colour Laser printers The capital cost of this type of printer is currently very high, but in due course they are lLkely to become as popular as their mono counterparts, especially when considering the speed and quality of output (300 dpi) and the relatively low consumable cost (about 25p per copy in-house, ranging up to œ2.50 commercially). Pen Plotters 23 10/11/94 Overview Presentsdon Graphics Until the introduction of the laser printer this was the mainstay of the graphics hardcopy business P excellent for producing smooth lines on paper and OHP transparencies where few colours are required. They can be driven by a wide range of software especially for those plotters adopting the industry standard language HPGL, 'However plotters are vector devices: they are not suited for area fill applications and are slow for complicated line drawings. The capital cost is fairly low (of the order of œ1,000 for an A4 plotter), and the cost per copy is less than 10p. Electrostatic ploners These are raster devices (both mono and colour), but have traditionally been driven from vector-based software. Hence they are usually provided with a rasterisation controller which nowadays tends to emulate the HPGL standard. It is also possible to drive these devices via a software PostScript interpreter. This is the only device capable of producing fast, high resolution (400 dpi) wide-bodied (A0) output in more than eight colours and extensive area fill. It is a multipass device and can produce more than 1000 dithered colours, but at reduced resolution. Both capital and consumable costs are very high for this type of device. Typical consumable costs would be from around œ2.50 (in-house)'up to œ50 (commercially). (Note: dithered colouring is the technique of generating different colours by grouping patterns of coloured dots, the effect on the human eye being that of a single colour. The use of dithering greatly increases the range of colours available, but also effectively reduces a device's resolution.) Thermal Transfer Prlnters A colour raster device that is becoming ever more popular, which creates images by transferring coloured wax to paper. It is a high quality hardcopy device supported by many software packages in the areas of presentation graphics, graphics design, image processing, solid modelling and scientific visualisation. In fact this is the only device that can speedily produce output on paper and OHP transparencies containing up to 4,000 dithered colours from a palette of 16.7 nullion, at a tolerable cost. Depending upon the interface connecdon, large image files can take a considerable time to transmit and process. It is a multipass device with a nominal resolution of 300 dpi which falls when dithering is used: this may unfortunately bzcome noticeable as 'banding' on smooth shaded objects and graduated fills. Since these devices have more recently been coupled with PostScript interpreters they have become more readily accessible by lots of software. The capital cost is fairly high (œ5,000 upwards), but is more than compensated for by the quality of output. Another drawback is the relathely high cost of consumables, which ranges from about 70p (in-house) up to œ10 (commercially). Ink Jet Prlnters Generally, these devices are not capable of reproducing the output quality, versadlity or efficiency of laser and thermal printers, but are popular with personal computer users for immediate hardcopy output. The capital cost is low and the consumable costs are tolerable: somewhat more expensive than the laser printer for mono, but less than the thermal printer for colour. The number of colours varies from around 300 for low-cost devices to full colour for high-end 'prepress' printers. 24 10/11/94 Overview Presentation Graphics Thermal Dye Subilmation Prlnters This hardcopy device offers full colour output similar to photographic quality. Capital cost is high, and consumable cost is also high, ranging from iE2 (in-house) up to œ20 (commercially). Fllm Recorders Very much in demand for producing 35mrn slide output from a wide range of software. Film offers very high resolution (at least 4,000 dpi) and excellent colour representation. Cost per 35mm slide ranges from 50p (in-house) up to œ5 (commercially). Unsupported Devices If the package does not support the particular device to which you wish to send output, but does support, for instance, CGM - then it should be possible to get hard copy output by having the CGM interpreted by other software (such as, for example, UNIRAS) which can produce the required printer output 25 10/11/94 Overview PresenSion Graphics GENERAL INFORMATION MATRIX This section of the Matnx tells you about any facilities in the packages which are normally cornmon to all types of presentanon graphics packages GENERAL Licence Arrangements Indicates any special deals by which you can obtain a package at less than the full commercial cost. Possible entries are - . 'CHEST discount' for a UK-wide education price;  'CHEST site licence' for site licences negotiated by CHEST;  'Select deal' for software available under the Microsoft Select scheme.  'Academic discount' for reduced prices, usually due to some special arrangement;  'No' for no special deal. Package Descripfion Description gives a very brief summary of what a package is, to give you a quick idea of its intended application area. Entries in Creative Graphics Matrix Entry is 'Yes' if there is further information in the 'Creative graphics matrix' section, otherwise 'No'. Entries in Data Driven Graphics Matrix Entry is 'Yes' if there is further information in the 'Data Driven graphics matrix' section otherwise 'No'. SYSTEM ENVIRONMENT Platform This entry tells you what sort of machine you need in order to run a package. Platform indicates the hardware, and operating system if relevant - for example Windows', 'Mac', Unix'. Disk requirements Tells you how much free space you need on your hard disk to install the package. In addition to the amount shown in the matrix, some packages require extra space in the installation process to unpack and assemble the software. Special requirements Indicates any special facilities you need in order to get the most out of the package. If extra clipart for instance is supplied on CD, enter 'CD' here. 26 lo/11/94 oV-PW Presentation GraDhics Network version available Is either 'Yes' or 'No'. The network version of a package allows several people to use it simultaneously, as if they had their own copy, and without affecting each other. The Package should have network installation options. USER ENVIRONMENT User interface This entry tells you about the general overall appearance of each package. User interface is usually 'WIMP' on PCs and Macs - for 'Windows Icons Menus and Pointer". In this case you can control programs by pointing and clichng with a mouse, and manipulating windows and icons on your computer screen. The main alternatives are menu-based programs - driven by a mouse or the keyboard, and command-driven programs. On-line help Can be 'Yes' if there is any help informatiorr within a package, or 'No'. If 'Yes', the help available is often enough to let you run the package without extensive documentation. OLE support Package supports Object Linking and Embedding. This allows graphics objects created by one piece of software to be embedded in a graphical object created by another but still maintain it's lihk with the original software - i.e. any changes made to the object will start up the original package and allow you to edit the original object . FONTS Extra Fonts supplied with package Most packages simply use the fonts which are available on their host computer, though some provide extra ones. The type of extra fonts which are available with the package are shown here, i.e. 'Truetype'. (See the entry for typeface in the glossary for a definition of the terms 'font' and 'typeface' as used in ffie matix.) Number Number of fonts suPPlied. IMPORT/EXPORT GRAPHICS FILE FORMATS A great many different formats are used for graphics files, which have evolved over the years. The term 'file format" refers to the way in which a graphic is stored in a computer file. Different programs use differentformats to store thefiles they create. These entries show you the main ones which each package can import (cope with) or export (produce). The entries here should enable you to deterrnine whether you can swap graphical images between two or more of the packages you want to use. The sect on 'Using Graphics Files and Images' gives rnore details on this subject. For extra information, you are recommended to consult Graphics File Formats by David C. Kay and John R. Levine, WinderestlMcGraw-Hill, 1992. It is sometimes adequate to use cut-and-paste for transferring graphics images between aDDlications on a sinBle machine: this saves you the trouble of choosing a graphicsfile 97 10/1 194 Overview Presentation Orgphics format for the exchange. OLE is another method by which graphics objects me be ernbedded in a presentation. File Type abbreviations AI Adobe Illustrator PCT MAC PI(S BMP Windows PCX CorelPHOTOPAINT CDR CorelDRAW PFB AdobeType 1 Font CGM Computer Graphics Metafile PIC Lotus PIC DRW Micrographx Draw SCD MatrixlImapro SCODL DXF AutoCAD DXF SUN Sun raster file EPS Encapsulated PostScript TGATARGA Bitmaps GEM GEM Files TIFF I Bitmaps GIF Compuserve Bitmaps 1TF ~TrueType Fonts HPGL HP Plotter language WMF Windows MetafUe JPEG JPEG Bitmaps WPG WordPerfect Graphic PCD Kodak Photo-CD XWD X-windows dump OTHER FEATURES Slide show facilities Is 'Yes' if the package can show a sequence of images, either under control or unattended, to support a talk or as an unattended demonstration. Templates/Style sheets Is 'Yes' if you can store general attributes without specific data, to act as templates for future productions; otherwise 'No'. Clip Art Supplied Is 'Yes' if the package includes a library of graphics images for inclusion in your charts, otherwise 'No'. Automatic backup facilities Is 'Yes' if you can tell the package to save your work every so often, or 'No' if you have to remember to save it yourself. Pantone matching Is 'Yes' if the package supports the internationally recognised Pantone system of specifying colours, otherwise 'No'. This feature is particularly important if you need to get the best output from bureaux. Extra Drivers with package Most Windows and Macintosh packages rely on their host system to deal with printers etc. Any extra facilities provided by individual packages are listed in this secdon, an example of this might be a 35mm type driver. 28 10/11/94 Overview Presentation Graphics DATA DRIVEN GRAPHICS FACILITIES MATRIX DATA HANDLING FACILITIES This section of the Matrix tells you about any facilities in the packages which can help you prepare your data for graphical display. Editing facilities Either 'Yes' or 'No' - indicates whether or not you can edit your data within a package before display. Calculation facilities Can be 'No', 'simple' (meaning that you can do simple transformations of data), or 'complex' (if you can carry out complex calculations on the data before displaying it - calculations such as those which you can perform in spreadsheets). Graph and data directly linked Tells you if a change to the data or alteration of the graph is automatically represented by an update of the other (i.e. the data or the graphical display) Statistical analysis Is either 'Yes' or 'No', to indicate whether a package can calculate statistical inforrnation about your data - such as mean and standard deviation. Maximum number of variables Indicates the number of variables the package can handle. Maximum number of data points Indicates the number of data points for each variable that the package can handle. Are missing values handled Indicates what the package does with missing values in your data. Packages with statistical capability tend to do something sensible with such cases, while other packages might ignore them or substitute a special value. Data Interpolation Indicates that data interpolation methods are available in the package. These vary and only a general indication is given, reference to the documentation should be made for more specific details. The cell entries may be 'No', '2D', '3D', '2D+3D'. 2D indicates support for 2D data. - i.e. parametric interpolation etc., similarly 3D indicates support for 3D data - i.e. irregular data converted to regular grid etc. 2-DIMENSIONAL DATA DISPLAY See CHAPTER 3 - 'TYPES of CHARr 3-DIMENSIONAL DATA DISPLAY See CHAPTER 3 - fTYPES of CHART' 29 10/11/94 Overview Presentation Graphics C)THER DlS;PLAY OPTIC)N! Error-bars (X or Y) Indicates if error bars supported - applies to line charts. Entries may be 'No', 'X-axis', 'Y-axis', 'Both'. Sometimes error-bars are also applied to other types of graphs, in such cases an entry (R) will appear in the 'Graph Type' cell., i.e. a bar/column chart supporting error-bars would have an (R) entry. Curve fftting Shows dhere are curve fitting options. These vary and only an indication 'Yes' or 'No' is given, reference to the documentation should be made for more specific details. Plot Maths functions Indicates if maths functions be plotted direcdy, for example from an equation. Entry is 'Ye.v' nr 'Nn' View Point adjustment Indicates that adjustment of the viewing position for 3-D graphical objects supported. Entry is 'Yes' or 'No' Read Data points If the value of data points be displayed by clicking at a position on the graph entry is 'Yes' otherwise 'No' CHART AXES This section of the Matrix deals with the appearance of axes in graph-type graphics. These explanations may be clearer if you refer back to Figure 3 in chapter 4: The anatomy of axes Axis The Axis topics refer to the actual line which makes up the axis, and the positioning of axes.  Change width/colour Can be 'Both' if both options are allowed, 'No' if neither of them, or the specific name if only one is available.  Allow Broken or Separated Axes Can be 'Both' if both options are allowed, 'No' if neither of them, or the specific name if only one is available. A 'broken' axis has a section missing, for example to allow both ends of an extreme range of values to appear on a graph of manageable size. If axes can be .separated., they can be positioned independently in the diagram - for example so they are set back from the data and do not meet at all.  Axis scaling user defined Is either 'Yes' if the user can choose the range of values to be represented along the axis, otherwise 'No' if the package forces the scaling. - Dual X/Y axes Is either 'No', the name of the dual axis - (i.e. Dual X or Dual Y), or 'Both' - Logarithmic axes Is 'Yes' if the package can produce logarithmic axes, otherwise 'No'. - Transposition of axes Is 'Yes' if the X and Y axes can be swapped over, otherwise 'No'. tn 10/11/94 Overview Presentation Graphics Axis labelling The Axis labelling topics refer to the various text items with which you can embellish an axis. - Allow edit of axis titles Is either 'Yes' if you can, or 'No'. . Position/move axis titles Is 'Yes' if the package allows you to influence the positioning of the axis titles, or 'No'. - Orientation of Axis titles Refers chiefly to the Y-axis title, which can be either 'horizontal' or 'vertical'. 'either' means that the package allows you to set the orientation of the title. - Scientific notation, Sub/Superscripts Is either 'Yes' if the package can cope with these in the axis title, or 'No'. . Foreign character support Is 'Yes', 'No' or limited', depending on how easily the package will allow you to use foreign (for example accented) characters in axis titles. Refer to manual for more details. Tick Marks The Tick mark topics concern the appearance and labelling of the tick marks along the axis.  Specify position Is 'Yes' if you can choose to have ticks inside, outside or across the axis (or indeed to have no tick marks), or 'No' if the package doesn't give you the option. -Format options For dck mark labels is 'Yes' if the package lets you choose the style of the tick mark labels (such as scientific, exponential, integer etc), otherwise 'No'. - Allow labelling only every Nth tickmark Is 'Yes' if the package lets you choose which tick marks to label, otherwise 'No'.  Grid lines on chart Is 'Yes' if you can choose to have tick marks running right across the chart, otherwise 'No'. OTHER CHART FACILITIES This section of the Matrix coversfloating text of any sort. Titles Is 'Yes' if the package lets you add a title, otherwise 'No'. Legends Is 'Yes' if you can add text anywhere on the chart, for example to act as a key, otherwise 'No'. Data Point labels Is 'Yes' if you can label individual points in the graph, 'yes, some' if you have some scope for labelling points, otherwise 'No'. Floating labels (annotation) Is 'Yes' if you can add general annotation to the chart, otherwise 'No'. 31 10/11/94 Overview Presenxion Graphics Chart size/position adjustment Is 'Yes' if the package allows you to adjust the size of the chart, otherwise 'No'. It is useful if you can do this: while it won't make any difference to what you see on the screen, you get the best quality when adding a graphic to a printed document if you get its size right in the graphics package, rather than having to adjust its size in the printed document. Background composition facilities Gives you an idea of what backgrounds you can add to your chart. The main choices are 'coloured' (a plain coloured background), 'bitmap' (meaning that you can import a picture, logo or other graphic to have as a chart background), 'pattern' (to have the package generate a background pattern), or 'graduated' (for a variably-shaded background). The presence of a background facility in a package doesn't tell you if it is 'easy' or 'difficult', just 'possible'. Frame/bounding box Is 'Yes' if the package allows you to put a frame around the chart, otherwise 'No'. Multiple charts on page Is 'Yes' if the package lets you create and group several charts on a single page, otherwise 'No'. CHART OBJECT ATTRIBUTES This section of the Matrzx covers the available attributes of items on the chart, or non- specific items which can be added to a chart. Number of line styles & widths The range of styles and widths are indicated by a general indication :- no choice <5 limited to five or less choices 5+ more than 5, reasonably unlimited If the package allows the user to produce a customised linestyle or variable width a (u) is added after the entry. Number of symbol styles Shows you how many different symbols a package can use in a chart. The range is :- no choice