[Qgis-developer] classification of rasters

[Marco Hugentobler]

Hi Tim,

For the project I'm working on, I need to have the possibility to colour a 
raster layer (e.g. a DEM) by building classes and assign a color to each. 
Afaik there is no possibility to do so in QGIS. Can I implement it in the 
raster transparency branch (even though it is not related to transparency)?

I wonder what the best way is to implement this behaviour. UMN mapserver 
preclassifies the expected values in a color table to make lookup faster 
(http://mapserver.gis.umn.edu/docs/howto/raster_data). But it also seems that 
their expressions for classifications can be more complicated than simple 
comparison operations. So I'm probably going to start by evaluating pixel 
values against a set of classes and see how the performance behaves.

What do you think?

Regards,
Marco