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Review of Visualisation Systems

5.2 IBM Data Explorer

5.2.1 - Hardcopy
5.2.2 - Files
5.2.3 - Animation/Video Creation

5.2.1 Hardcopy

There are 3 modules in DX that will produce an image from some data: render, display and image. Render produces the image but doesn't display it while display will display it too but requires a camera module to produce transformations on the viewpoint. The image tool combines both display and a camera, in addition allows the user to save and print images. If the render tool is used it would be necessary to output the image from the render module into write image or the image tool. The write image requires the user to open its control panel and type in the name of the format (new users will need to refer to manual pages to determine what this string is and may find the control panels a little difficult to understand). The image tool uses pull down menus to select the format. Using print image under the "file" menu of the Image tool, the standard formats provided to send directly to a printer are: Colour PS, Greyscale PS, Encapsulated Colour PS and Encapsulated Greyscale PS. In addition it is possible to save images using "save image" under the "file" menu: as a PS file, in RGB (grouped together), R+G+B (all R, then all G then all B), or TIFF. Having saved the image this can be converted to other typical hardcopy image formats using a public domain image tool, e.g. San Diego Supercomputing Centre (SDSC) tools. Example macros and networks are available at the Cornell anonymous ftp site (ftp.tc.cornell.edu), under pub/Data.Explorer/Extensions/Import.and.Export.Macros. The macros automatically create a temporary tiff file, convert it to the requested format using the SDSC imconv routine, and finally delete the temporary tiff file.

5.2.2 Files

Apart from the creation of image formats, as detailed above, the only other standard module for creating output files from dx is the export module. This exports data from Data Explorer but only produces dx formatted or bin files (dx is the default, needs to have the text "dx" or "bin" in the "format" entry of the control panel). The bin format is only recommended on IBM POWER Visualization Systems. With "dx" format additional modifiers apply:

5.2.3 Animation/Video Creation

The primary tool used for the creation of Animation sequences is the sequencer - this can be found under the category "Special". Given a min, max and step value (passed from other modules or set explicitly), this basically creates a sequence of integers. Although like more advanced animation utilities, the sequence can be played forwards, backwards, set to a particular value, paused, or set to loop (either to the last then jump back to the first or bounce forwards then backwards). The default interface resembles a simple VCR control panel, see Figure 11

To set the values used by the sequencer, an additional control panel needs to be opened. By selecting the box containing "...", the panel shown in Figure 12 becomes visible.

On its own this module is not particularly useful for general purpose animations, but in combination with others can become a powerful animation aid. For example, when used with the transformation tool Compute it can produce a sequence of float values that could modify camera position, or with the interactor Selector could cycle through time series data. Several networks exist in the standard example directory, /usr/lpp/dx/samples/programs, to illustrate this. Only one sequencer is allowed in a network, but more experienced users can build networks such that this produces side by side animations.

Review of Visualisation Systems
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