Hello everyone!Some time ago I've asked about problems with gdalwarp (the e-mails below). I tried to utilize Python binding instead but got the same results. This brief script overlays the Europe map (GeoTIFF with geotransform) onto a MERIS images (PDS file with GCPs). But the result looks wrong again - the map is very small and apperas in the upper left corner (attached file).
GCPfile='MER_RR__2PNPDK20030809_100609_000022512018_00466_07534_3898.N1' geotransformfile = 'europe.tif' outfile = 'colocated.tif' # open input datasets src_ds = gdal.Open(geotransformfile) dst_ds = gdal.Open(GCPfile) # create writable copy of the destination image driver = gdal.GetDriverByName( "GTiff" ) out_ds = driver.CreateCopy(outfile, dst_ds, 0 ) # reproject onto destination image with GCPs gdal.ReprojectImage(src_ds, out_ds)Can you please confirm that this is a bug in GDAL? If so I will issue a bug report.
Thank you in advance! AntonPS. If the GCPs in the destination image are replaced with a GeoTransfrom generated using the gdal.GCPsToGeoTransform() function, the result looks much better but the image is still rather distorted. Which is understandable because curvature of a MERIS images (given by GCPs) cannot be fully explained by few numbers in the geotransform.
On 12/16/2011 03:56 PM, Anton Korosov wrote:
Hi! I'm not sure but probably my question is related to the one below. I'm trying to mosaic one MODIS images onto another with GDAL: gdal_translate HDF4_EOS:EOS_SWATH:"/Data/sat/GDAL_test/MYD021KM.A2011228.0925.005.2011229003113.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB -b 1 /data/modis1.tif gdal_translate HDF4_EOS:EOS_SWATH:"/Data/sat/GDAL_test/MOD021KM.A2011229.1125.005.2011229195243.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB -b 1 /data/modis2.tif gdalwarp modis1.tif modis2.tif Bu the results looks weird - the first image is on top of the second one but it is very small, distorted and in the top-left corner (though they cover approximately the same area). Do I understand right that such operation would work only when the target image georeference is defined by GeoTransform and not by GCPs? Can I also ask if it is a big work to include ability of GDAL to warp onto grid with GCPs (or RPC or geolocation array) ? And if it is planned in some future? Thank you! Anton On 12/15/2011 03:47 PM, Knut-Frode Dagestad wrote:Hi, Hróbjartur Þorsteinsson explained to me a near-hidden feature of GDAL, namely to reproject one image onto the coverage of another. Given two images: imageA.tiff imageB.tiff Then an empty image can be created from image A with e.g. $ gdal_translate -ot Float32 -scale 0 0 999 999 -a_nodata 999 imageA.tiff domainA.tiff And then imageB can be warped onto the extent of this image simply with: $ gdalwarp imageB.tiff domainA.tiff domainA.tiff will then contain the data from imageB, exactly co-located with imageA. The problem is that this only works when imageA contains a geotransform, and not when it contains only GCPs. So my question is: Is there any workaround to warp data from one image onto another image which is geolocated by GCPs only? With the -to option of gdalwarp it is possible to pass some parameters to GDALCreateGenImgProjTransformer2(). In the documentation of this function I find the following option: "METHOD: may have a value which is one of GEOTRANSFORM, GCP_POLYNOMIAL, GCP_TPS, GEOLOC_ARRAY, RPC to force only one geolocation method to be considered on the source dataset." http://www.gdal.org/gdal__alg_8h.html#94cd172f78dbc41d6f407d662914f2e3 But there is no corresponding option to force use of GCP_POLYNOMIAL for the *destination* dataset. I guess this is a bad sign? Thank you for any help! Knut-Frode _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
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