[Gdal-dev] projection coordinates support

[April Shimitz]

Frank,

We've been having some issues with accuracy when using the
Get/SetGeoTransform methods to pass our corner coordinates through GDAL.
The transformation coefficients retrieved with GetGeoTransform are not as
precise as the values given to SetGeoTransform. I noticed your note on the
GDAL doc. that you are not completely happy with this mechanism either. Do
you have any plans for improvement of this in the near future? Since LAS
only needs the functionality to store the coordinates at the extents of the
image, we'd like to have the ability to do that more directly. We have been
considering developing a new class to store/retrieve the corner coordinates
and would like to move on that now. Our plan for the class is a simple
object to contain the exact projection corner coordinates, removing the
usage of an intermediate transformation equation, thereby returning to the
caller the exact values that were set in the object. This class would be
useful to a number of other format drivers as well I am sure (including
ones we plan to develop in the future), so I'd like to implement it as part
of the GDAL core. Let me know if we should move forward with this plan or
if you have any ideas/input.

April

**************************************
April Shimitz
USGS/EROS Data Center
SAIC
Programmer Analyst
Land Analysis Systems (LAS)
shimitz at usgs.gov