Ahlzen/TopOSM — pull request #4 by asciiphil (2012-07-06 18:27:26+00:00)
Title: Elevation JPEGs

This branch contains changes to prep_toposm_data to store the preprocessed NED GeoTIFFs with JPEG compression. These files are anywhere from 30% to 10% the size of the DEFLATEd GeoTIFFS.

Mapnik renders the JPEG GeoTIFFs just fine, and I haven't been able to see any quality difference in its output. ImageMagick won't read them, so the process involves making JPEG-compressed hillshade files for storage and uncompressed hillshade and colormap files for composition.

I also delete the colormap files after using them to generate the hypsorelief files, since they're not used in the rendering process. That's easy enough to fix if you want to keep them around.