[gdal-dev] Re: Hillshade + Topographic Map??

[Joaquim Luis]

> 5) Looked at GMT and I cannot find the options to load two rasters on 
> top of each other.

Tim,

You don't load the two grids on top of one-another. Illumination is NOT 
like transparency. It uses the gradients of the grid, projects it into 
the direction of light and than change the color in the HSV space (the 
S(aturation) component) and converts back to RGB


The links that I sent you have the scripts used to produce the figures. 
You can also look at this one for a very simple illumination in bw, but 
the procedure for color illumination is exactly the same.

http://gmt.soest.hawaii.edu/gmt/html/GMT_Docs.html#x1-1300007.5

> 6) MIRONE - again cannot see how to do this from within the application.

Well, I can give you a 'click-recipe' if you want, but Mirone won't be 
able to deal with the such big grids as yours.
Anyway, here is a step-by-step example
https://sites.google.com/site/mironehowtos/basic/shade-illuminations