"joem", It seems that your input dataset is very close to the dateline, and very likely crossing it. I'm not that surprised that GDALSuggestedWarpOutput() has issues at that discontinuity. But I think it might have indeed operated correctly. If the extent of the dataset crosses the dateline the resulting eastings in Web Mercator coordinates will go from about -20 million to about 20 million. A huge width. GDALSuggestedWarpOutput() tries to scale the computed dimensions so that the result has roughly the same number of pixels as the input. So the huge width becomes a reasonable width, and the reasonable height becomes a small height. In that situation, you could try using modified input and output proj.4 strings by adding +over to the normal proj.4 definition. See https://trac.osgeo.org/proj/wiki/GenParms This should produce an output datasets with eastings that go beyond the 20 million limit. You might want to cut it into 2 parts afterwards.
Best regards, Even > > > I am working on a tool to project FAA charts from Lambert Conformal Conic > to Web Mercator (EPSG 900913). It seems to be producing correct output > except for a FAA chart of the East Aleutian Islands. When I traced the > problem in my code, it appears that GDALSuggestedWarpOutput() is giving me > a width and height far too small given the input tiff had larger > dimensions. The source GeoTiff has dimensions of 15555x5786 but > GDALSuggestedWarpOutput() gives a suggested width of 17050 and a height > of 178. A height of 178 pixels surely has to be wrong. I have added > the well-known text and proj.4 output from gdalinfo.exe of the input tiff > below. Although I am not entirely sure if I should, I have been using > the values supplied by GDALSuggestedWarpOutput() for creating my output > Geotiff as if the output will always be valid. > > * Why is GDALSuggestedWarpOutput() giving bad values for the width and > height of the output tiff? > * Is this incorrect usage of GDALSuggestedWarpOutput() or is it a bug? > > > PROJ.4 : '+proj=lcc +lat_1=54.66666666666666 +lat_2=49.33333333333334 > +lat_0=52.16666666666666 +lon_0=-177.5 +x_0=0 +y_0=0 +datum=NAD83 +units=m > +no_defs ' > > OGC WKT : > PROJCS["unnamed", > GEOGCS["NAD83", > DATUM["North_American_Datum_1983", > SPHEROID["GRS 1980",6378137,298.2572221010002, > AUTHORITY["EPSG","7019"]], > AUTHORITY["EPSG","6269"]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433], > AUTHORITY["EPSG","4269"]], > PROJECTION["Lambert_Conformal_Conic_2SP"], > PARAMETER["standard_parallel_1",54.66666666666666], > PARAMETER["standard_parallel_2",49.33333333333334], > PARAMETER["latitude_of_origin",52.16666666666666], > PARAMETER["central_meridian",-177.5], > PARAMETER["false_easting",0], > PARAMETER["false_northing",0], > UNIT["metre",1, > AUTHORITY["EPSG","9001"]]] > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
