[I] RS_ZonalStats line rois: all_touched is ignored, and the default rule burns every traversed cell [sedona]

["james-willis (via GitHub)" <gi...@apache.org>]

james-willis opened a new issue, #3322:
URL: https://github.com/apache/sedona/issues/3322

   Probing `RS_ZonalStats` with LINESTRING rois on a 20x20 unit-pixel grid (the GH-3118 `RasterizationTests` fixtures) against GDAL/rasterio ground truth shows two line-specific behaviors in the rasterization path:
   
   1. **`all_touched=true` is ignored for line geometries.** The count never changes with the flag; cells that the segment's envelope touches but does not cross are never included. GDAL/rasterio `all_touched=True` includes them.
   
      | segment | default | all_touched (Sedona) | all_touched (GDAL/rasterio) |
      |---|---|---|---|
      | `LINESTRING (1.5 2.75, 10.5 7.25)` | 10 | 10 | 15 |
      | `LINESTRING (0.75 1.25, 4.25 11.75)` | 11 | 11 | 15 |
      | `LINESTRING (2.5 2.5, 9.5 9.5)` | 8 | 8 | 15 |
   
   2. **The default (no `all_touched`) line rule burns every traversed cell.** GDAL's default line rasterization uses the centre/diamond crossing rule, which burns fewer: e.g. `LINESTRING (1.3 2.7, 8.6 11.4)` burns 17 cells in Sedona but 10 in GDAL/rasterio. (Corner-crossing segments mask this — their traversal and diamond counts coincide, which is why the GH-3118 fixtures agree by default.)
   
   Together these mean a line roi's zonal statistics differ from GDAL-based engines in both flag positions. Surfaced by the SedonaDB↔Sedona Spark parity suite (apache/sedona-db `integration/spark-parity`), where SedonaDB (GDAL rasterizer) matches rasterio in all four regimes.
   
   GH-3118's direction-independence itself holds in every probed case (forward and reversed WKTs agree), as does the polygon path (the coastline fixture's pinned 1738/1842 counts match exactly).
   


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Re: [I] RS_ZonalStats line rois: all_touched is ignored, and the default rule burns every traversed cell [sedona]

["sudhamsh-git (via GitHub)" <gi...@apache.org>]

sudhamsh-git commented on issue #3322:
URL: https://github.com/apache/sedona/issues/3322#issuecomment-6261943574

   Hi, I'd like to work on part 1 of this (all_touched being ignored for lines). I'm a student contributing as part of a university software engineering course. rasterizeGeometry never passes allTouched to rasterizeLineString, so lines burn the same cells either way. I have a fix that follows GDAL's ALL_TOUCHED line walk (GDALdllImageLineAllTouched), which gives 15 cells for the three segments here, with tests based on those numbers. I'll leave part 2 alone since it changes default results. Does that sound OK?


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