[gdal-dev] gdalwarp error 6 issues

[Even Rouault]

Zoltan,

> Hi,
> I've been struggling to get some 3200 orthos mosaicked and tiled.
> They are very old and have really bad projection definitions, pixel
> sizes and metadata funnies.
> I'm down to the last 261, and have hit a brick wall.
> Given that gdalwarp works on this image when I leave out s_srs and t_srs
> (see below), I'm not sure if this is a bug related hiccough or a proj
> issue.
> 
> I have compiled the latest "GDAL 2.1.1, released 2016/07/07" myself, on
> Ubuntu 16.04.1 Desktop:  Linux gl05 4.4.0-36-generic #55-Ubuntu SMP Thu
> Aug 11 18:01:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
> 
> 
> 
> I get the following error from gdalwarp:
> 
>     ERROR 6: Unable to load PROJ.4 library (libproj.so), creation of
>     OGRCoordinateTransformation failed.

Hum, if you get this message, then reprojection should never succeed. How did 
you compile GDAL with ./configure --with-static-proj4 or without it ? If 
without it, you must be sure to have the development package of proj installed 
so that proj.so links to proj.so.1 or proj.so.9 or whatever the soname of your 
proj is.

> 
> I have tried various different gdalwarp parameters - even leaving
> gdalwarp to sense in input projection and me only specifying the output
> projection.
> If I leave out both s_srs and t_srs then gdalwarp does work but
> obliviously does not reproject to Lo19.

> I have even tried feeding the output of this redundant gdalwarp into a
> gdalwarp with t_srs, but no success.
> 
> Specifying only t_srs (as above) on many other orthos on Lo17 & Lo21
> does work so it is likely that the way this projection is embedded in
> this ortho is the problem.

Yes, the way ER Mapper encodes the projection is non-standard and thus GDAL 
reports a LOCAL_CS that cannot be used to automatically get a proj.4 string. 
GDAL has some handling for some of those non-standard encodings, but not for 
your ones, so overriding it with -s_srs is needed.

> I have tried stripping it out with gdal_edit.py but haven't gotten that
> right yet.
> 
> Anyone with pointers or ideas on this?

+datum=Hartebeesthoek94 is not recognized by proj.4. 

Why not using EPSG:2049 instead or the proj.4 expension ? I also see that 
gdalsrsinfo EPSG:2049 expands to

PROJ.4 : '+proj=tmerc +lat_0=0 +lon_0=21 +k=1 +x_0=0 +y_0=0 +axis=wsu 
+ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs '

So note the +axis=wsu parameter for the south-orientated variant

Or perhaps this doesn't make sense in your context of producing a GeoTIFF, so 
in that case you might just want to use the above proj.4 string without 
+axis=wsu. Note that for proj the Hartebeesthoek94 datum is equivalent to 
WGS84.

Even

> 
> My last effort before email this list is below, as is the gdalinfo output.
> 
> Thanks in advance,
> Zoltan
> 
> gdalwarp -s_srs '+proj=tmerc +lat_0=0 +lon_0=21  +k=1 +x_0=0 +y_0=0
> +datum=Hartebeesthoek94 +units=m +no_defs'  \
>           -t_srs '+proj=tmerc +lat_0=0 +lon_0=19  +k=1 +x_0=0 +y_0=0
> +datum=WGS84 +units=m +no_defs' \
>           -r cubicspline -multi -overwrite -of GTiff -co TFW=YES -co
> COMPRESS=JPEG -co JPEG_QUALITY=75 -tr 0.75 -0.75 \
>           /mnt/sdb1/used_images/dwa_2000/3220/3220CC01.tif \
> /mnt/sda1/gisdata/raster/used_2016/dwa_2000/3220/3220CC01.tif
> #
> #
> gdalinfo   /mnt/sdb1/used_images/dwa_2000/3220/3220CC01.tif
> #
> Driver: GTiff/GeoTIFF
> Files: /mnt/sdb1/used_images/dwa_2000/3220/3220CC01.tif
> Size is 6729, 7720
> Coordinate System is:
> LOCAL_CS[" Geocoding information not available Projection Name = WGS
> 1984 Lo21 Units = meters GeoTIFF Units = meters",
>      UNIT["metre",1,
>          AUTHORITY["EPSG","9001"]]]
> Origin = (-93872.189308887900552,-3625321.216973003931344)
> Pixel Size = (0.750000000000000,-0.750000000000000)
> Metadata:
>    AREA_OR_POINT=Area
>    TIFFTAG_DOCUMENTNAME=hetotiff
>    TIFFTAG_IMAGEDESCRIPTION=ER Mapper 6.4 hetotiff
>    TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
>    TIFFTAG_SOFTWARE=IMAGINE TIFF Support
> Copyright 1991 - 1999 by ERDAS, Inc. All Rights Reserved
> @(#)$RCSfile: etif.c $ $Revision: 1.9.1.3 $ $Date: 2002/07/29 15:39:06EDT $
>    TIFFTAG_XRESOLUTION=1
>    TIFFTAG_YRESOLUTION=1
> Image Structure Metadata:
>    INTERLEAVE=PIXEL
> Corner Coordinates:
> Upper Left  (  -93872.189,-3625321.217)
> Lower Left  (  -93872.189,-3631111.217)
> Upper Right (  -88825.439,-3625321.217)
> Lower Right (  -88825.439,-3631111.217)
> Center      (  -91348.814,-3628216.217)
> Band 1 Block=6729x1 Type=Byte, ColorInterp=Red
> Band 2 Block=6729x1 Type=Byte, ColorInterp=Green
> Band 3 Block=6729x1 Type=Byte, ColorInterp=Blue

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