I'm trying to use Mapnik to render tiles to overlay along with USGS DOQQ satellite tiles, but I think I'm running into some projection issues.
I'm stitching together the DOQQ satellite tiles gathered using the USGS Seamless service, which have a 3.33% overlap. The DOQQ metadata claims to be using NAD83 and GRS80 in UTM Zone 12. After stitching, the satellite tiles look perfect. When I use Mapnik+OSM data to render tiles, they don't seem to line up with any consistency when overlaid with the DOQQ images. Here is an example of what I've come up with so far, where red outlines are overlapping USGS tile boundaries, and green outlines are the Mapnik tiles I generated. Also included is the Python code I'm using to stitch everything together: http://wtisgpub.coe.montana.edu/raw.jpg http://wtisgpub.coe.montana.edu/raw.pycode Some things match closely, like the city streets around Thermopolis in the center of the image, but others don't. For example, highway 120 to the north-west appears high compared to the satellite data, but US-20 appears low in the south-east. I'm a CS person, and not very experienced in projection systems. Two of us have been staring at this problem for a few days now without any luck--maybe our problem is obvious to someone more experienced? Thanks in advance. :) -- Jeffrey Sharkey [EMAIL PROTECTED] http://www.jsharkey.org/ _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
