Dear List, We are in the process of creating an ARM build of our system, and we have discovered some differences in GDAL behavior between the two.
One is the declared block size of a simple RGB PNG image, which we use for some raster import tests. The image is 320x225 and gdalinfo on x86 reports that for the block size of the three bands also. However, on ARM it reports the block sizes as 320x1. ubuntu@guest:~/work/heavydb-internal$ gdalinfo Tests/Import/datafiles/raster/beach.png Driver: PNG/Portable Network Graphics Files: Tests/Import/datafiles/raster/beach.png Size is 320, 225 Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 0.0, 0.0) Lower Left ( 0.0, 225.0) Upper Right ( 320.0, 0.0) Lower Right ( 320.0, 225.0) Center ( 160.0, 112.5) Band 1 Block=320x1 Type=Byte, ColorInterp=Red Band 2 Block=320x1 Type=Byte, ColorInterp=Green Band 3 Block=320x1 Type=Byte, ColorInterp=Blue PNG file here (as a Zip to avoid risk of binary change)... https://drive.google.com/file/d/1MaK_oBvX8YjgYNMrDpc0Hv7SlQFZ4890/view?usp=sharing The second difference is the point order of the (single, outer) ring of a MULTIPOLYGON when exported and re-imported as GeoJSONL. In either the export or the import (haven't looked that deeply yet) the ring is getting reversed. Note that the ring data is actually very bogus (lots of repeated points and no avoidance of self-intersection). We simplified it to topologically valid data and then there are no differences between platforms. So it's possible that the CW/CCW auto-detection/reversal is getting confused by some floating-point precision differences (which we have also encountered in other places). We are not worried about this one, having simplified the test so that it now passes, but the difference is still slightly concerning. These differences are consistent on both an AWS G5g.8xlarge and an nVidia GH200, both running Ubuntu 22.04 and our own build (done on the AWS instance) of GDAL 3.7.3. I intend to try 3.9.2 also, as we are intending to upgrade to that for our next release. (repost after canceling original post held for moderation due to attachment size) -- Simon Eves Senior Rendering Engineer +1 (415) 902-1996 simon.e...@heavy.ai <http://www.heavy.ai>
_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
