[gdal-dev] RPC

[Even Rouault]

Le lundi 18 janvier 2016 08:39:06, Surya Prakash a écrit :
> Hi ALL,
> I have some imagery associated with RPC files. The locational accuracy of
> the images defined by the RPCs is quite poor and I would like to update
> the RPCs by using some additional GCPs. How to do this, Please guide me.

You might find this interesting :
http://fwarmerdam.blogspot.fr/2013_09_01_archive.html

Are you sure the RPC you got is poor ? Several points need to be taken into 
account to get precise wrapping when using RPCs: if the angle of the image is 
far from nadir, you will need to use a DEM. And one point to take into account 
when doing so is that the elevations of the DEM must be relative to the WGS84 
ellipsoid. For that either you need to correct the DEM before using GDAL, or 
you must use GDAL trunk and have the DEM SRS be a COMPD_CS with a vertical 
datum grid shift. There also were issues with half-pixel shift in RPC 
application that have been fixed very recently in GDAL.

> 
> Thanks & regards
> SPR

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