Introduction

Unimap is an interactive, menu driven package for contouring and visualising spatial data in 2 or 3 dimensions. It can also display 4 related variables. It contains very sophisticated facilities but, in spite of that, is extremely easy to use.

This workbook is designed to teach you the basics of using Unimap. You are advised to work through the book, using the provided data, so that the pictures you get correspond to the pictures in the book. It will take no more than one hour and may take considerably less.

Unimap can read several types of data but the most important are regular and irregular. It is essential to understand the difference between the two. Think of the area in which your data lies and imagine it covered by a grid. The points at which the lines of the grid cross are called grid nodes and the spaces between are grid cells. Unimap works with data at those grid nodes.

Regular data: there is a Z value at every node of the grid. This kind of data may have been produced by a program which has calculated the values from some theoretical model and so can obtain a Z value for any X,Y values.
Irregular data: Z values are scattered across the grid in an irregular fashion. This is more likely to have come from an experiment. For example, think of Ordnance Survey mapping data. You could not collect spot heights at every node of a grid; some places would be in the middle of a river or half way down a precipice. You measure heights in accessible places and the result is irregularly spaced data.

Before contour lines or 3 dimensional surfaces can be drawn irregular data must be converted into regular data. This is called interpolation. It means taking the known values of Z and estimating the probable values at all the grid nodes. Unimap does these calculations for you.

A data file of irregular data that you use will normally consist of three numbers on each line - X, Y and Z. Other formats are possible but this is the simplest and is the format of the data that you will use in this workbook. A file of regular data is arranged differently and is discussed in the Unimap Solutions book that is the companion to this book.

In this workbook each page is a simple exercise. At the top of the page is a brief description of what you are going to do, then comes a picture of the screen as it will appear while you do the exercise, next the instructions for doing the exercise and finally a few points to note.

The screen is divided into panels for its menus thus. In the instructions you will be told which panel to look at and what to select from it.

Contents Page

Unimap Workbook 		1		February 1994

Graphics Multimedia Virtual Environments Visualisation Contents