Color Tables

Owned by Erlend Kvinnesland
Last updated: Dec 09, 2013
3 min read

Introduction

Geocap comes with a set of predefined color tables which can be seen in the toolbox. These color tables are of course customizable, or you can create your own color table from scratch.

A color table consists of a finite set of colors. Once the number of colors is set, the color values themselves can be assigned. This is typically done using a combination of interpolation and direct color picking using a color triangle. This is explained below. When applied to a dataset, the colors present in the table are mapped onto the dataset in the range specified in the mapping range field. This mapping range can be changed after a dataset has been displayed.



In this section:

Applying a color table

By default the color tables shown in the lower right corner of Geocap will be used to display a dataset. You can change these color tables by selecting one of them, right-click another color table in the toolbox and select Activate.

You can also use drag and drop to drag a color table from the toolbox and drop it onto a displayed dataset in the graphical window.

A third option is to set a specific color table in the command menu before executing the command.

Importing color tables

It is possible to import color tables from files with RGB values listed row-wise with any non-numerical characater as separator. Each RGB value must be in the range 0-255.
 

Example file1: 

176 15 15 
178 25 23 
179 34 30 
181 43 37 
182 52 45 
183 62 52 
185 71 59 

It is also possible to import color tables that has been exported from Kingdom in *.clm format.

Creating or editing a color table

Click the icon in the toolbox to create a new color table or right click an existing color table and select edit.


The color table menu

The Number of colors field defines how many colors Geocap uses to map a dataset.

The mapping range defines how the colors are distributed on your dataset:

  • Use data range - will map colors onto the complete range of the targeted dataset.
  • Relative range % - lets you set lower an upper bounds in target range using relative values between 0 and 100.
  • Absolute range - will map colors onto the range given by these values. Data values outside the range will be clamped to the top or bottom colors of the table.

In addition to determening the number of colors and setting the data range for color mapping, there are four icons of special importance in the top right corner of the window:

  • The icon is used to set the interpolation points in the color table.
  • The icon is used to execute the interpolation. Make sure that the horizontal pick line is situated between the two relevant interpolation points.
  • The icon is used to remove all interpolation points previously set and start over.
  • The icon is used to reverse the color table.

Use the color triangle, type in RGB values or use the palette to set the colors at different interpolation points.

Adjusting map range

You can adjust the mapping range of a dataset that has already been displayed in the graphical window. This is done by clicking the icon in the toolbar, and then clicking on the graphical element in the graphical window. The Range Controller menu will appear and show the data scalar range and the min and max value which the color table has been mapped against. You can change these values by using the up and down arrows on your keyboard, or by dragging the sliders in the menu.