Implement Attached Neighbour Detection

[jravani]

Overview

No neighbour detection exists in City2TABULA.
This sub-issue introduces a method to detect which buildings are attached to each other based on their footprints or envelopes.

Attached neighbours are buildings that:

• Touch or overlap in 2D
• Are separated only by very small geometric gaps (tolerance required)

This is a prerequisite for Party Wall Detection.

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Requirements

1. Compute building footprints or envelopes.
2. Detect potential neighbours using spatial operations:
   • ST_Intersects(footprint, footprint)
   • ST_Touches
   • ST_DWithin(footprint, footprint, tolerance)
3. Store neighbour relationships in a table or directly in building attributes.
4. Ensure the method works across datasets with varying geometry quality.

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Output

For each building:

• neighbour_ids (array or mapping table)
• Boolean has_attached_neighbours

These results will be used by Sub-Issue B.

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Notes

• Tolerance is required due to minor dataset gaps.
• 3DBAG has cleaner geometry; DE/AT may need relaxed thresholds.