Propagate input dims/coords through true_color() (#3429)

.claude/sweep-metadata-state.csv

@@ -6,6 +6,7 @@ focal,2026-06-10,3217,MEDIUM,4;5,"Re-audited 2026-06-10 (agent-ad0d55a894c6abc60
 geotiff,2026-06-09,3116,HIGH,2;3,"Re-audited 2026-06-09 (agent-ae89ff94a64e3ee8f worktree, branch deep-sweep-metadata-geotiff-2026-06-09). CUDA available; all 4 backends (numpy/cupy/dask+numpy/dask+cupy) run live. Focus: surfaces changed since the 2026-05-18 audit (unpack rename + GPU/dask+GPU support #3075, pack=True #3065/#3079, masked int->float promotion #2994, bbox= reads, rioxarray param alignment #2963, no-georef VRT coord synthesis #2824, GeoTransform omission #2971). Live probes: unpack attrs (scale_factor/add_offset/mask_and_scale_dtype/nodata/masked_nodata), masked=True promotion, default masked=False, bbox window+transform shift, multi-band band=N, dims/name/coords (incl. coord dtype) all identical across the 4 backends; nodata_pixels_present absent on dask paths is the documented lazy contract, not a bug. pack->unpack round trips verified on numpy/dask/gpu-write; pack of a cupy-backed read raises via the known cupy+xarray xp.astype incompat (see memory cupy_where_astype_incompat; dependency-pin fix, raises loudly, not a metadata bug). VRT reads (full/masked/window/bbox) and no-georef TIFF reads agree across the 4 backends. NEW HIGH finding #3116 (Cat 2+3): to_geotiff(non_georef_da, out.vrt, tile_size=N) wrote a corrupt index for arrays spanning >1 tile -- write_vrt derives placement from each source GeoTransform and non-georef tiles all carry the identity transform, so rasterX/YSize collapsed to one tile and every DstRect landed at the origin; reads silently returned a single tile (24x32 in -> 16x16 out). Gap left by #2966/#2971 (tests only covered one non-georef source). Fix: _write_vrt_tiled threads per-tile pixel offsets through _build_vrt -> write_vrt via internal dst_offsets kwarg; write_vrt refuses >1 all-non-georef sources without explicit placement and rejects dst_offsets alongside georeferenced sources. 18 new tests in tests/vrt/test_non_georef_placement_3116.py incl. 4-backend round trip, dask-backed and plain-ndarray writes, XML DstRect assertions, georef placement regression, and the write_vrt error contract. Full vrt suite 520 passed; write+round-trip suites 1292 passed."
 interpolate,2026-06-12,3288,MEDIUM,5,kriging K_inv-None fallback was numpy-backed on all backends and misnamed the variance raster; fixed via #3288. All 4 backends verified end-to-end on GPU host. LOW (documented only): template nodatavals/_FillValue copied verbatim while fill_value is the actual output sentinel; tests codify attrs==template.attrs
 mcda,2026-06-10,3147,HIGH,1,"constrain() dropped all attrs (res/crs/nodatavals) whenever exclude non-empty (xr.where takes attrs from scalar fill); fixed via attrs restore, tests for numpy/dask/dask+cupy. All other mcda funcs keep attrs/coords/dims on all 4 backends. Out-of-scope crashes noted for backend-parity: owa broken on cupy (numpy order-weights x cupy) and on dask (da.sort does not exist); sensitivity monte_carlo crashes on cupy/dask+cupy (.values on cupy); xr.where compute on cupy/dask+cupy hits known cupy13.6/xarray2025.12 incompat."
+multispectral,2026-06-20,3429,MEDIUM,2;3,"true_color() hardcoded y/x dims + dropped extra coords; fixed PR #3434 (all 4 backends verified, CUDA available)"
 polygonize,2026-06-12,3293,MEDIUM,1,"Audited 2026-06-12 (agent-a86d90abea41b04cf worktree, branch deep-sweep-metadata-polygonize-2026-06-12). CUDA available; all 4 backends (numpy/cupy/dask+numpy/dask+cupy) run live for int, float+NaN, and no-georef rasters. polygonize returns vector output (numpy/awkward/geopandas/spatialpandas/geojson), not a DataArray, so Cats 2-4 reinterpreted as transform/CRS/value-dtype propagation. Transform auto-detect (attrs['transform'] -> rio.transform() -> x/y coords, #2536/#2607) and CRS resolution run in public polygonize() before dispatch, so all 4 backends emit identical columns, bounds, and CRS (verified live). Column value dtype follows input dtype on every backend. NEW MEDIUM finding #3293 (Cat 1): _detect_raster_crs ignored the _xrspatial_no_georef marker that _detect_raster_transform honours, so a geotiff-reader crs_only raster (attrs carry both crs and the marker; metadata_to_attrs writes crs independent of has_georef) produced a GeoDataFrame claiming EPSG:#### over pixel-space geometries -- the #2536 metadata-lies-about-the-data mismatch through the marker channel. contour.py imports the same helper and inherits the fix. Fix: early return None in _detect_raster_crs on the marker + docstring note; 2 new tests in TestPolygonizeCRSPropagation. polygonize+contour suites 274 passed; all 9 auxiliary polygonize test files 303 passed. rotated-read path unaffected (reader drops CRS there). No CRITICAL/HIGH/LOW findings."
 proximity,2026-05-29,2723,MEDIUM,4;5,"Audited 2026-05-29 (agent-a61dbadc2452a2003 worktree, branch deep-sweep-metadata-proximity-2026-05-29). CUDA+cupy available; all 4 backends (numpy/cupy/dask+numpy/dask+cupy) run live end-to-end for proximity/allocation/direction, both bounded (finite max_distance) and unbounded. Cat 1 (attrs res/crs/transform/nodatavals/_FillValue), Cat 2 (coords + coord dtype), and Cat 3 (dims) all preserved and identical across the 4 backends -- public funcs wrap with xr.DataArray(coords=raster.coords, dims=raster.dims, attrs=raster.attrs). NEW MEDIUM finding #2723 (Cat 4 + Cat 5): (a) bounded dask+numpy path (_process_dask -> da.map_overlap with meta=np.array(())) declared output dtype float64 while the chunk fn returns float32 and numpy/cupy/dask+cupy + the unbounded KDTree path all declare float32; docstrings show dtype=float32. Fix: meta=np.array((), dtype=np.float32). (b) dask backends leaked an internal dask op name (_trim-<hash>, _kdtree_chunk_fn-<hash>, asarray-<hash>) into result.name while numpy/cupy return None. Fix: assign result.name=None after construction in all 3 public funcs (xarray ignores a name=None kwarg for named dask arrays, so the reset must happen post-construction). Same .name-leak class as zonal #2611. PR #2728 off child branch deep-sweep-metadata-proximity-2026-05-29-01. New parametrized regression test test_output_metadata_consistent_across_backends asserts declared dtype float32 + name None across all 4 backends x 3 funcs x bounded/unbounded; full test_proximity.py suite 93 passed. No other CRITICAL/HIGH/MEDIUM/LOW findings."
 rasterize,2026-06-09,3087,MEDIUM,1,GeoDataFrame .crs dropped on no-like path (Cat 1); fixed via #3087 emitting attrs crs/crs_wkt when output has no CRS. like-path attrs/coords/dims/nodata verified live on all 4 backends (CUDA available); Cats 2-5 clean.

xrspatial/multispectral.py

@@ -1821,19 +1821,19 @@ def true_color(r, g, b, nodata=1, c=10.0, th=0.125, name='true_color'):
         warnings.simplefilter('ignore')
         out = mapper(r)(r, g, b, nodata, c, th)
 
-    # TODO: output metadata: coords, dims, attrs
-    _dims = ['y', 'x', 'band']
-    _attrs = r.attrs
-    _coords = {'y': r['y'],
-               'x': r['x'],
+    # Preserve the input's spatial dims/coords instead of hardcoding y/x,
+    # then append the band dim.  Hardcoding raised KeyError on lat/lon
+    # rasters and dropped extra coords like spatial_ref (issue #3429).
+    _dims = [*r.dims, 'band']
+    _coords = {**{name: r[name] for name in r.coords},
                'band': [0, 1, 2, 3]}
 
     return DataArray(
         out,
         name=name,
         dims=_dims,
         coords=_coords,
-        attrs=_attrs,
+        attrs=r.attrs,
     )
 
 

xrspatial/tests/test_multispectral.py

@@ -884,6 +884,42 @@ def test_true_color_mismatched_backends_raises():
         true_color(red, green, blue)
 
 
+# true_color metadata propagation (issue #3429) ----------
+def _tc_band(backend):
+    data = np.random.default_rng(3429).random((6, 6)).astype(np.float32)
+    return create_test_raster(
+        data, backend=backend, dims=['lat', 'lon'],
+        attrs={'res': (0.5, 0.5), 'crs': 'EPSG: 5070'},
+    )
+
+
+@pytest.mark.parametrize(
+    "backend",
+    ["numpy",
+     pytest.param("dask+numpy", marks=dask_array_available),
+     pytest.param("cupy", marks=cuda_and_cupy_available),
+     pytest.param("dask+cupy", marks=cuda_and_cupy_available)],
+)
+def test_true_color_preserves_non_yx_dims(backend):
+    # true_color used to hardcode y/x and raised KeyError on lat/lon input.
+    r = _tc_band(backend)
+    g = _tc_band(backend)
+    b = _tc_band(backend)
+    out = true_color(r, g, b)
+    assert out.dims == ('lat', 'lon', 'band')
+    np.testing.assert_allclose(out['lat'].data, r['lat'].data)
+    np.testing.assert_allclose(out['lon'].data, r['lon'].data)
+    assert out.attrs == r.attrs
+
+
+def test_true_color_preserves_extra_coords():
+    # A non-spatial coord (e.g. rioxarray's spatial_ref) must pass through.
+    r = _tc_band('numpy').assign_coords(spatial_ref=0)
+    out = true_color(r, r.copy(), r.copy())
+    assert 'spatial_ref' in out.coords
+    assert int(out['spatial_ref']) == 0
+
+
 # NDSI ----------
 @pytest.fixture
 def expected_ndsi():