Exclude centre cell from morph_erode/dilate when kernel[centre]==0 (#1397)#1398
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brendancol merged 1 commit intomainfrom May 1, 2026
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Exclude centre cell from morph_erode/dilate when kernel[centre]==0 (#1397)#1398brendancol merged 1 commit intomainfrom
brendancol merged 1 commit intomainfrom
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…1397) The numpy and CUDA kernel functions seeded the running min/max from the centre cell before iterating the structuring element. When the kernel had a 0 at the centre, the loop skipped the centre cell but the seed value already came from it, so the centre still contaminated the result. Fix: drop the centre seed and assign from the first kernel-included neighbour, then compare against subsequent ones. NaN propagation now only fires when a NaN neighbour is actually included by the kernel. Cells where the kernel covers no non-zero entries return NaN. Affects all four backends (numpy, cupy, dask+numpy, dask+cupy).
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…1401) Three modules audited 2026-04-30. - fire: clean (per-pixel ops only; NaN guards via x!=x; CUDA bounds use strict <; division guarded; CPU/GPU/dask paths line-for-line equivalent; no CRIT/HIGH/MEDIUM). - terrain_metrics: LOW only (Inf input not rejected, propagates; dask+cupy non-nan boundary path double-pads with consistent output). - morphology: HIGH x 2 fixed. - #1397 / PR #1398: morph_erode/dilate seeded centre cell into the running min/max even when kernel[centre]==0, contaminating the result with the excluded pixel (all four backends). - #1399 / PR #1400: _morph_chunk_numpy and _morph_chunk_cupy used result[hy:-hy, hx:-hx] which becomes the empty slice 0:-0 for 1xN or Nx1 kernels, raising ValueError on the dask backends while numpy and cupy paths handled them.
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Summary
morph_erodeandmorph_dilatewhen the structuring element has a 0 at the centre. Previously the running min/max was seeded from the centre cell before the kernel loop, so the centre still influenced the result even when the kernel excluded it._erode_kernel_numpy,_dilate_kernel_numpy,_erode_gpu,_dilate_gpu.Fixes #1397.
Test plan
pytest xrspatial/tests/test_morphology.py xrspatial/tests/test_morphology_derived.pypasses (70 tests)