geointel/docs/17-max-prep/M9_GEOSPATIAL_EDGE_CASES.md

M9 Geospatial Edge Cases

Codex must account for these cases early to avoid later rewrites.

Invalid polygon

Examples:

• self-intersection,
• unclosed ring,
• empty coordinates,
• wrong coordinate nesting.

Required behavior:

• reject with validation error,
• return specific message,
• do not persist.

MultiPolygon

Required behavior:

• accept for areas and vector features,
• compute total area across all parts,
• display as a single layer.

CRS mismatch

Scenario:

• reference data is EPSG:31370,
• API uses EPSG:4326,
• raster processing may use native CRS.

Required behavior:

• store original CRS in dataset metadata,
• transform API geometries to EPSG:4326 for frontend,
• use projected CRS for area/length calculations when needed,
• document transformations.

Very large file

Required behavior:

• reject files above configured limit with clear error,
• do not load huge files into memory at once,
• expose future chunking/tile strategy.

Raster without georeference

Required behavior:

• accept only as non-georeferenced image if supported,
• mark geospatial operations unavailable,
• do not pretend map alignment exists.

Feature outside selected area

Required behavior:

• clip if operation requested,
• otherwise keep original and display warning if used for area analysis.

Geometry collection

Required behavior:

• reject for V1 unless explicitly converted,
• explain supported geometry types.

Zero-area feature

Required behavior:

• keep for line/point layers,
• reject or ignore for polygon-area metrics,
• record warning in analysis result.

Duplicate features

Required behavior:

• do not automatically delete without audit trail,
• expose duplicate count in data quality metadata.

Antimeridian/global edge cases

Not relevant for Kempen V1. Document as out of scope.