Toggle Colour Interpolation
This function toggles an attribute known as Colour Interpolation from on to off. The default state for this attribute is on. The Colour Interpolation attribute only has relevance for DTMs which have been drawn with the DRAW SHELLS function. This function and the TOGGLE COLOUR INDEX INTERPOLATION function determine the presentation style of DTMs when false colouring of triangles is used with the DRAW SHELLS function.
The DRAW SHELLS function draws a DTM so that you can have different colours associated with different attribute values from the DTM. The most common example of this is where contour bands (that is the Z field) are drawn in different colours.
With the Colour Interpolation attribute on, the colours are smooth shaded from one colour to the next.
With the Colour Interpolation attribute off, the colours are drawn as solid bands for each of the contour intervals with a distinct change in colour from one contour band to the next.
See the table below for a description of the possible combinations of Colour Interpolation and Colour Index Interpolation and a description of the results.
| Colour Index Interpolation | Colour Interpolation | Result |
|---|---|---|
| on | on | The object is drawn with smooth gradation of colours from one contour band to the next. |
| on | off | The object is drawn with solid colours for each of the contour bands with very distinct changes in colour at each contour interval. |
| off | on | This is a valid choice but not very useful. The object is drawn with smooth colour shading although the gradation in colours is determined by using the colour values at each triangle vertex but not by interpolating the colour within the colour map. |
| off | off | The object is drawn in the colour as defined in the Styles File or by using the SET OBJECT STYLES function. |
This table describes the four possible combinations of the Colour Index Interpolation and Colour Interpolation attributes and the results of the different combinations.