gdal warp and snap

[mdsumner]

extend -tap to work with -ts,-te and not require -tr

• [x] allow -tap -ts -te
• [x] modify -te to source pixel alignment (when no -t_srs)
• [ ] modify -te to target pixel alignment (when -t_srs supplied)

I think in the t_srs case it's kind of pointless, because you have an implied resolution from -te/-ts and then you would only align the -te to that (I guess that's ok).

https://github.com/OSGeo/gdal/pull/7073#issuecomment-1386206357

we want this to avoid having to do raster logic outside, so any -te when not changing the crs will do what the RasterIO lib does (snaps to native)

[mdsumner]

Notes

• -tr and -ts are checked for consistency, errors if -ts and -tr are both used
• -tap if set is then checked for -tr and errors (so we need to else that check, for -tr or -ts)
• then, this block won't be run but we must add a check for -tr (nForceLines/Pixels) and recompute extent:

      if (psOptions->bTargetAlignedPixels ||
            (psOptions->bCropToCutline &&
             psOptions->aosWarpOptions.FetchBool("CUTLINE_ALL_TOUCHED", false)))
        {
            psOptions->dfMinX = floor(psOptions->dfMinX / psOptions->dfXRes) *
                                psOptions->dfXRes;
            psOptions->dfMaxX =
                ceil(psOptions->dfMaxX / psOptions->dfXRes) * psOptions->dfXRes;
            psOptions->dfMinY = floor(psOptions->dfMinY / psOptions->dfYRes) *
                                psOptions->dfYRes;
            psOptions->dfMaxY =
                ceil(psOptions->dfMaxY / psOptions->dfYRes) * psOptions->dfYRes;
        }

[mdsumner]

earlier notes

https://gist.github.com/mdsumner/5d7b156611a6fa267dfe368ea6e2a385

[mdsumner]

draft here: https://github.com/mdsumner/gdal/blob/warp-tap-with-ts/apps/gdalwarp_lib.cpp

[mdsumner]

related work on the python side 🤔

https://github.com/rasterio/rasterio/issues/1931