[gdal-dev] An issue about using GDALWARP to do the NTv2 transformation

[heng.feng]

http://osgeo-org.1803224.n2.nabble.com/file/n5838904/gdalwarp_problem.doc
gdalwarp_problem.doc 

Hi there,

I was trying to use GDALWARP command to do the NTv2 transformation on some
German map data (raster data). However I have come across a lot of errors
saying "failed to find a grid table for the location". I used the same grid
shift file and the same projection settings in the ogr2ogr command to do the
NTv2 transformation on the MapInfo map data files (vector data) we have got
. It seems working perfectly without any error message. The grid shift file
was downloaded from 
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=de&tl=en&u=http%3A%2F%2Fcrs.bkg.bund.de%2Fcrseu%2Fcrs%2Fdescrtrans%2FBeTA%2Fde_dhdn2etrs_beta.php
this link .

I am not sure whether I have used the GDALWARP command correctly. It seems
that I got the error messages for all the raster map data I have got here by
running the GDALWARP command to do the NTv2 transformation on them. I have
attached two screenshots for your reference. As follows, please find the
GDAL command I was using and some the error messages copied from the FWTools
shell window. Note that I have turned on the debug mode before running the
command in FWTools shell window:

C:\Program Files\FWTools2.4.7>gdalwarp -s_srs "+proj=tmerc +lat_0=0
+lon_0=12 +k =1.000000 +x_0=4500000 +y_0=0 +ellps=bessel +datum=potsdam
+nadgrids=C:\fh\comar ch\BETA2007.gsb +units=m +wktext" -t_srs "+proj=utm
+datum=WGS84 +zone=32" C:\fh \comarch\backdrops\s4_01_01\l0.tif
C:\fh\comarch\backdrops\s4_01_01\l0_test.tif
pj_open_lib(proj_def.dat): call
fopen(C:\PROGRA~1\FWTOOL~1.7\proj_lib\proj_def.d
at) - succeeded
pj_open_lib(proj_def.dat): call
fopen(C:\PROGRA~1\FWTOOL~1.7\proj_lib\proj_def.d
at) - succeeded
Processing input file C:\fh\comarch\backdrops\s4_01_01\l0.tif.
pj_open_lib(proj_def.dat): call
fopen(C:\PROGRA~1\FWTOOL~1.7\proj_lib\proj_def.d
at) - succeeded
pj_open_lib(proj_def.dat): call
fopen(C:\PROGRA~1\FWTOOL~1.7\proj_lib\proj_def.d
at) - succeeded
pj_open_lib(C:\fh\comarch\BETA2007.gsb): call
fopen(C:\fh\comarch\BETA2007.gsb)
- succeeded
NTv2 DHDN90   62x84: LL=(5.5,47) UR=(15.6666667,55.3)
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0347670dW,55.2216906dN)
   tried: C:\fh\comarch\BETA2007.gsb
0pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350256dW,55.2215588dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350256dW,55.2215588dN)
   tried: C:\fh\comarch\BETA2007.gsb
NTv2 - loading grid DHDN90
pj_open_lib(C:\fh\comarch\BETA2007.gsb): call
fopen(C:\fh\comarch\BETA2007.gsb)
- succeeded
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350534dW,55.2212791dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350534dW,55.2212791dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350813dW,55.2209994dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0350813dW,55.2209994dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): used DHDN90
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.0351091dW,55.2207198dN)
   tried: C:\fh\comarch\BETA2007.gsb
.................................
.................................
.................................
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.1075622dW,54.4761871dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.1075622dW,54.4761871dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.1075888dW,54.4759073dN)
   tried: C:\fh\comarch\BETA2007.gsb
pj_apply_gridshift(): failed to find a grid shift table for
                      location (5.1075888dW,54.4759073dN)
   tried: C:\fh\comarch\BETA2007.gsb
100 - done.

I did not copy all the error messages here as there are quite an amount of
messages. Although we did get some resulting file after running this
command, I did not manage to see anything (just blank) when opening the
files in our map data/image tools. 

I am just wondering whether you are aware of any reason why this happens.
Your help would be much appreciated.

Thanks & Best Regards,
Heng
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