[GRASS-user] Slow display of images (rasters)

[Morten Sickel]

I am working with some aerial photograps, I have sets of pancromatic black and white pictures and colored infrared pictures. the pan-images were imported directly and displays quite qickly, each image being about 150M. When I imported the colored IR pictures, they came in as three bands, each about the same size as the pancromatic picture. Then I used r.composite to recreate the colored picture, and got a file on about 500M. When I use d.rast to display the composite file, things takes ages, nothing seems to happen for a long while. d.rast uses more or less 100% of the CPU but not much memory. I recall the xdriver being slow when displaying rasters with a large color space as an issue some years ago, but I thought that worked better now.. Are there anything I can do to make it work better? I have presently 24 bits color depth, but that is going to increase to 36 bits (3x12bits) later on, if that goes even slower, I will have a problem...

My machine is a 1,5 GHz with 1 GB of RAM running linux, no speedmonster, when displaying the same maps in qgis, it goes quite a bit faster.

Morten


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