feat: Add user-defined Oblique Stereographic CRS fixture - #71
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128x128 extract of a source.coop/dataforcanada COG whose CRS (New Brunswick Stereographic, equivalent to EPSG:2953) is stored as user-defined geo keys with the projection origin in ProjNatOrigin*/ProjScaleAtNatOrigin rather than ProjCenter*. Parsers that read the ProjCenter* keys for CT_ObliqueStereographic place the image near (0, 0). From source-cooperative/cog-viewer#40 Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Regenerating the fixture with a plain gdal_translate silently writes ProjectedCSTypeGeoKey = 2953 instead of the user-defined keys the fixture exists to exercise. Read the raw GeoKeys with async-tiff and assert the full set, and run pytest in CI. async-tiff comes from PyPI because conda-forge has no osx-arm64 build. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
kylebarron
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Sep 25, 2026
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Upstream PR source-cooperative/cog-viewer#40 has a GeoTIFF that doesn't render correctly because we don't parse the CRS correctly.
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Written by Claude (Claude Code) on behalf of @kylebarron, not by @kylebarron.
From source-cooperative/cog-viewer#40
Adds
real_data/source-coop-dataforcanada/O2308000_7586000_cog.tif, a 128x128 extract of a source.coop/dataforcanada COG (44 KB).The CRS is New Brunswick Stereographic (equivalent to EPSG:2953), but it is stored as user-defined geo keys (
ProjectedCSTypeGeoKey = 32767,ProjCoordTransGeoKey = CT_ObliqueStereographic). The projection origin is inProjNatOriginLatGeoKey/ProjNatOriginLongGeoKey/ProjScaleAtNatOriginGeoKey. A parser that reads theProjCenter*keys for this method gets an origin of (0, 0) and puts the image near Null Island.A plain
gdal_translateof the source doesn't keep those keys: GDAL identifies the CRS as EPSG:2953 by name and writesProjectedCSTypeGeoKey = 2953instead. The extract assigns the same WKT with thePROJCS/GEOGCSauthority codes removed. All 19 geo keys in the extract match the source file. The README has the exact command and thelistgeooutput.pixi run checkpasses locally.🤖 Written by Claude Code