[Gdal-dev] Help with reprojection of a quicklook...

[Frank Warmerdam]

Jeff Jacober wrote:

> Thanks a bunch for the VRT info Frank.
> 
> I think I am very close now, but still not quite there.
> 
> First, a quick gdalinfo on my .jpg file produces this:
...
> Now I need to warp it.  When I try:
> 
> gdalwarp -t_srs "+proj=utm +zone=11 +datum=WGS84" wrk.vrt utm11.tif
> 
> I get the following output:
> 
> ERROR 1: Failed to import coordinate system `'.
> Creating output file is that 977P x 505L.
> ERROR 1: Failed to import coordinate system `'.
> :0...10...20...30...40...50...60...70...80...90...100 - done.
> 
> And the output image doesn't appear to look quite right. It seems no 
> matter what target projection I specify, I get the same result.
> 
> Do I need to somehow specify a coordinate system for my raw input file? 
> My control point X Y coords are in lat/long. Is this just assumed?

Jeff,

Yes, the problem is presumably that the .vrt file (and the original JPEG)
have no coordinate system so instead of reprojecting the image to
UTM 11, it is really just doing the GCP based warp to north up but still
in the original coordinate system.

You could specify the WGS84 geographic coordinate system in the .vrt file,
but it is somewhat easier in your case just to supply the source coordinate
system in the gdalwarp call:

   gdalwarp -s_srs WGS84 -t_srs "+proj=utm +zone=11 +datum=WGS84"
         wrk.vrt utm11.tif

Good luck,

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