Implement Party Wall Detection (Shared Walls)

[jravani]

Overview

Once attached neighbours are identified (Sub-Issue A), this sub-issue implements surface-level detection of shared walls (“party walls”).

A party wall is a wall surface belonging to one building that is directly adjacent or overlapping with a wall surface of another building.

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Requirements

1. Retrieve candidate neighbour pairs from Sub-Issue A.

2. For each building pair, compare vertical wall surfaces:

   • Filter surfaces by tilt ≈ 90 degrees
   • Perform geometric tests:
     • ST_3DIntersects
     • ST_3DDWithin (tolerance)
     • 2D projection + overlap checks

3. Mark matched surfaces as party walls:

   • is_party_wall = true
   • neighbour_building_id
   • Optional: shared area / shared height

4. Store results in {schema}.{lod}_child_feature_surface.

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Output

For each child-feature surface:

• is_party_wall
• neighbour_building_id
• Optional: metrics for overlap area/height

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Notes

• Must handle gaps and slight misalignments in LoD2 datasets.
• Performance optimisation will be required for large datasets.