[Gdal-dev] Should These Maps Be Aligned?

Kent Eschenberg eschenbe at psc.edu
Fri Oct 26 17:28:14 EDT 2007


The roads from roadtrl020.tar.gz and the relief map from srld48i200l.tar.gz 
(nationalatlas.gov) don't seem aligned near Los Angeles (I haven't looked 
closely elsewhere). Some roads are over the ocean.

I converted the relief map from its Lambert projection to geographic (i.e., 
longitude and latitude) with gdalwarp. As far as I can tell the roads already 
use that projection. No prj file came with the roads but the included text file 
has this section:

===
Spatial_Reference_Information:
   Horizontal_Coordinate_System_Definition:
     Geographic:
       Latitude_Resolution: 0.000278
       Longitude_Resolution: 0.000278
       Geographic_Coordinate_Units: Decimal degrees
     Geodetic_Model:
       Horizontal_Datum_Name: North American Datum of 1983
       Ellipsoid_Name: GRS1980
       Semi-major_Axis: 6378137
       Denominator_of_Flattening_Ratio: 298.257222
===

I wrote a C++ program that with the gdal/ogr library reads these then writes 
them in the VTK XML format. These can then be used by a scientific 
visualization program (ParaView) where we are also displaying earthquake 
simulation results. I could have made an error, of course.

Is there some non-commercial software I could run on Linux to display the road 
and relief maps together to check whether they are aligned?

Thanks!
Kent
Pittsburgh Supercomputing Center



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