[gdal-dev] Re: Warping an image with both a geotransform and control points

Chaitanya kumar CH chaitanya.ch at gmail.com
Thu Jul 7 07:42:22 EDT 2011


Jan,

If you are just going to shift the image, just the GeoTransform element
should be enough. You don't need the GCPs.

On Thu, Jul 7, 2011 at 3:04 PM, Jan Hartmann <j.l.h.hartmann at uva.nl> wrote:

> **
> Hi all,
>
> This has come up before, but I'm still struggling for an answer. I want to
> rubbersheet an already projected image with control points, so as to remove
> small errors.On a suggestion by Frank (
> http://lists.osgeo.org/pipermail/gdal-dev/2009-February/019775.html) I
> produced a VRT file of the georeferenced image and added control points to
> shift the image 1000m to the right. (see below). However,  GDALWARP ignores
> the control points and returns the original georeferenced image. When I
> remove the georeferencing information, it does use the control points, but
> returns a raw image shifted to the right.
>
> Is it possible to rubbersheet a georeferenced image with control points, or
> am I chasing a red herring?
>
> Thanks,
>
> Jan
>
> <VRTDataset rasterXSize="310" rasterYSize="343">
>   <SRS>PROJCS[&quot;Amersfoort / RD
> New&quot;,GEOGCS[&quot;Amersfoort&quot;,DATUM[&quot;Amersfoort&quot;,SPHEROID[&quot;Bessel
> 1841&quot;,6377397.155,299.1528128000008,AUTHORITY[&quot;EPSG&quot;,&quot;7004&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;6289&quot;]],PRIMEM[&quot;Greenwich&quot;,0],UNIT[&quot;degree&quot;,0.0174532925199433],AUTHORITY[&quot;EPSG&quot;,&quot;4289&quot;]],PROJECTION[&quot;Oblique_Stereographic&quot;],PARAMETER[&quot;latitude_of_origin&quot;,52.15616055555555],PARAMETER[&quot;central_meridian&quot;,5.38763888888889],PARAMETER[&quot;scale_factor&quot;,0.9999079],PARAMETER[&quot;false_easting&quot;,155000],PARAMETER[&quot;false_northing&quot;,463000],UNIT[&quot;metre&quot;,1,AUTHORITY[&quot;EPSG&quot;,&quot;9001&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;28992&quot;]]</SRS>
>   <GeoTransform> -8.5000000000000000e+03,  1.0000000000000000e+03,
> 0.0000000000000000e+00,  2.8750000000000000e+05,  0.0000000000000000e+00,
> 1.0000000000000000e+03</GeoTransform>
>   <Metadata />
>   <Metadata domain="IMAGE_STRUCTURE">
>     <MDI key="INTERLEAVE">BAND</MDI>
>   </Metadata>
>   <GCPList>
>     <GCP Id="" Pixel="0.0000" Line="0.0000" X="1.000000000000E+03"
> Y="0.000000000000E+00" />
>     <GCP Id="" Pixel="1000.0000" Line="0.0000" X="2.000000000000E+03"
> Y="0.000000000000E+00" />
>     <GCP Id="" Pixel="1000.0000" Line="1000.0000" X="2.000000000000E+03"
> Y="2.000000000000E+03" />
>     <GCP Id="" Pixel="0.0000" Line="1000.0000" X="1.000000000000E+03"
> Y="1.000000000000E+03" />
>   </GCPList>
>   <VRTRasterBand dataType="Float64" band="1">
>     <Metadata />
>     <ColorInterp>Gray</ColorInterp>
>     <SimpleSource>
>       <SourceFilename relativeToVRT="1">test.tif</SourceFilename>
>       <SourceBand>1</SourceBand>
>       <SourceProperties RasterXSize="310" RasterYSize="343"
> DataType="Float64" BlockXSize="310" BlockYSize="3" />
>       <SrcRect xOff="0" yOff="0" xSize="310" ySize="343" />
>       <DstRect xOff="0" yOff="0" xSize="310" ySize="343" />
>     </SimpleSource>
>   </VRTRasterBand>
> </VRTDataset>
>
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-- 
Best regards,
Chaitanya kumar CH.
/tʃaɪθənjə/ /kʊmɑr/
+91-9494447584
17.2416N 80.1426E
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