[gdal-dev] Geolocation Arrays ??

Sun Feb 12 10:56:24 EST 2012

Etienne

the algorithm that finds the target extent is not in the transformer

Brian

On Sun, 2012-02-12 at 13:17 -0200, Etienne Tourigny wrote:
> Brian,
> 
> I'm not sure I understand your point - I probably don't understand the
> algorithm enough. Are both the forward and reverse transformations
> necessary in all cases?
> 
> My point is that, if (manually) adding the -te option to gdalwarp is
> necessary in most cases, why not (automatically) setting the extents
> from the min/max of the geolocation arrays instead of trying to
> calculate them?
> This could fix when the algorithm fails or generates an extent that is
> too large.
> 
> Etienne
> 
> On Sun, Feb 12, 2012 at 12:38 PM, Brian Case <rush at winkey.org> wrote:
> > the forward transform is pretty strait forwards, however the reverse is
> > not, it creates back-mask (a geo-referenced image that contains the x/y locations
> > in the source image). the points that the warper tries to transform to
> > figure out the target extent are no-data in the back-mask.
> >
> > Brian
> >
> > On Sun, 2012-02-12 at 12:25 -0200, Etienne Tourigny wrote:
> >> Brian, thanks fot the info.
> >>
> >> I have seen that on all tests I made (without -te option).  Sometimes
> >> it fails completely, and sometimes it creates an extent that is too
> >> large.
> >>
> >> Would it make sense, if the geolocation SRS and target are SRS are the
> >> same (e.g. WGS84), to calculate the target extents from the min/max of
> >> the geolocation arrays?
> >> Current extent detection code seems to try many transformations with
> >> proj4, and either fails or creates an extent that is too large.
> >>
> >> regards,
> >> Etienne
> >>
> >>
> >> On Tue, Feb 7, 2012 at 8:46 PM, Brian Case <rush at winkey.org> wrote:
> >> > Etienne
> >> > with the transformer the way it sits now, in most cases you will need to
> >> > specify -te xmin ymin xmax ymax with gdalwarp to avoid that error
> >> >
> >> > Brian
> >> >
> >> >
> >> > On Tue, 2012-02-07 at 19:22 -0200, Etienne Tourigny wrote:
> >> >> Even, Frank,
> >> >>
> >> >> thanks for your answers.  I have run into a problem with using
> >> >> gdalwarp with geoloc transform.
> >> >>
> >> >> In ticket #1895 there is an hdf file for which the HDF4 driver creates
> >> >> GEOLOCATION metadata.
> >> >>
> >> >> Trying gdalwarp on it gives an error, and the result transform is
> >> >> incorrect.  Am I doing something wrong, or is this a bug?
> >> >>
> >> >> command is : gdalwarp -geoloc -t_srs EPSG:4326
> >> >> HDF4_SDS:UNKNOWN:"A2006005182000.L2_LAC_SST.x.hdf":13 tmp1.tif
> >> >> more info below:
> >> >>
> >> >> $ gdalinfo HDF4_SDS:UNKNOWN:"A2006005182000.L2_LAC_SST.x.hdf":13
> >> >> Driver: HDF4Image/HDF4 Dataset
> >> >> Files: A2006005182000.L2_LAC_SST.x.hdf
> >> >> Size is 389, 602
> >> >> Coordinate System is `'
> >> >> Metadata:
> >> >> [...]
> >> >> Geolocation:
> >> >>   LINE_OFFSET=0
> >> >>   LINE_STEP=1
> >> >>   PIXEL_OFFSET=0
> >> >>   PIXEL_STEP=1
> >> >>   SRS=GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS
> >> >> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AUTHORITY["EPSG","4326"]]
> >> >>   X_BAND=1
> >> >>   X_DATASET=HDF4_SDS:UNKNOWN:"A2006005182000.L2_LAC_SST.x.hdf":11
> >> >>   Y_BAND=1
> >> >>   Y_DATASET=HDF4_SDS:UNKNOWN:"A2006005182000.L2_LAC_SST.x.hdf":12
> >> >> Corner Coordinates:
> >> >> [...]
> >> >>
> >> >> $ gdalwarp -geoloc -t_srs EPSG:4326
> >> >> HDF4_SDS:UNKNOWN:"A2006005182000.L2_LAC_SST.x.hdf":13 tmp1.tif
> >> >> Creating output file that is 31119P x 5864L.
> >> >> Processing input file HDF4_SDS:UNKNOWN:A2006005182000.L2_LAC_SST.x.hdf:13.
> >> >> ERROR 1: Too many points (441 out of 441) failed to transform,
> >> >> unable to compute output bounds.
> >> >> 0...10...20...30...40...50...60...70...80...90...100 - done.
> >> >>
> >> >> $ gdalinfo tmp1.tif
> >> >> Driver: GTiff/GeoTIFF
> >> >> Files: tmp1.tif
> >> >> Size is 31119, 5864
> >> >> Coordinate System is:
> >> >> GEOGCS["WGS 84",
> >> >>     DATUM["WGS_1984",
> >> >>         SPHEROID["WGS 84",6378137,298.257223563,
> >> >>             AUTHORITY["EPSG","7030"]],
> >> >>         AUTHORITY["EPSG","6326"]],
> >> >>     PRIMEM["Greenwich",0],
> >> >>     UNIT["degree",0.0174532925199433],
> >> >>     AUTHORITY["EPSG","4326"]]
> >> >> Origin = (-90.198287963867188,90.300000000000011)
> >> >> Pixel Size = (0.015398926739995,-0.015398926739995)
> >> >> Metadata:
> >> >>   AREA_OR_POINT=Area
> >> >> Image Structure Metadata:
> >> >>   INTERLEAVE=BAND
> >> >> Corner Coordinates:
> >> >> Upper Left  ( -90.1982880,  90.3000000) ( 90d11'53.84"W, 90d18' 0.00"N)
> >> >> Lower Left  ( -90.1982880,   0.0006936) ( 90d11'53.84"W,  0d 0' 2.50"N)
> >> >> Upper Right (     389.001,      90.300) (Invalid angle, 90d18' 0.00"N)
> >> >> Lower Right (     389.001,       0.001) (Invalid angle,  0d 0' 2.50"N)
> >> >> Center      ( 149.4013126,  45.1503468) (149d24' 4.73"E, 45d 9' 1.25"N)
> >> >>
> >> >>
> >> >> Regards,
> >> >> Etienne
> >> >>
> >> >>
> >> >> On Tue, Feb 7, 2012 at 7:05 PM, Frank Warmerdam <warmerdam at pobox.com> wrote:
> >> >> > On Tue, Feb 7, 2012 at 7:40 AM, Etienne Tourigny
> >> >> > <etourigny.dev at gmail.com> wrote:
> >> >> >> Hi all,
> >> >> >>
> >> >> >> I would like to have information on the status of geolocation array
> >> >> >> support in GDAL.
> >> >> >>
> >> >> >> The relevant RFC4 (http://trac.osgeo.org/gdal/wiki/rfc4_geolocate)  is
> >> >> >> still "under development", and the information there is that
> >> >> >> GDALCreateGeoLocTransformer "is currently partially implemented".
> >> >> >
> >> >> > Etienne,
> >> >> >
> >> >> > I think the geoloc transformer received some fixes from someone
> >> >> > other than myself and now is working reasonable well.  It would
> >> >> > be desirable to freshen up the RFC and get it passed but it isn't
> >> >> > particularly a priority of mine so I'm not likely to drive it in the
> >> >> > very near future.
> >> >> >
> >> >> > Best regards,
> >> >> >
> >> >> > --
> >> >> > ---------------------------------------+--------------------------------------
> >> >> > I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> >> >> > light and sound - activate the windows | http://pobox.com/~warmerdam
> >> >> > and watch the world go round - Rush    | Geospatial Software Developer
> >> >> _______________________________________________
> >> >> gdal-dev mailing list
> >> >> gdal-dev at lists.osgeo.org
> >> >> http://lists.osgeo.org/mailman/listinfo/gdal-dev
> >> >
> >> >
> >
> >