Building Regulariser

Parallel Threshold

• Type: Decimal (meters)
• Default: 1.0
• Range: 0.1 - 10.0

What it does: Defines the maximum distance between two edges to be considered "parallel" and merged into a single aligned edge.

Technical details: Uses spatial tolerance to detect edges that should be parallel in reality but aren't due to digitization errors or GPS noise. When two edges are within this threshold distance and have similar angles, they are replaced by a single perfectly parallel edge.

How to adjust:

• Lower (0.5-1.0): Strict alignment, only truly parallel edges are merged
• Higher (1.5-2.0): More permissive, merges edges that are "approximately" parallel
• Recommendation: Start with 1.0 and increase if buildings remain jagged

Simplify Tolerance

• Type: Decimal (meters)
• Default: 0.5
• Range: 0.1 - 5.0

What it does: Controls geometry simplification using the Douglas-Peucker algorithm. Removes small segments and details smaller than the specified tolerance.

Technical details: After regularisation, vertices are simplified to reduce polygon complexity. A vertex is removed if it deviates less than the tolerance from the line connecting its neighbors. This reduces file size and improves rendering performance.

How to adjust:

• Lower (0.1-0.3): Preserves more details, keeps small architectural features
• Higher (0.5-1.0): More aggressive simplification, removes small irregularities
• Recommendation: Use 0.3 for complex buildings, 0.5 for simple rectangular buildings

Allow 45° Angles

• Type: Checkbox
• Default: Enabled

What it does: Allows the algorithm to snap edges to 45° angles in addition to 0° and 90°.

Technical details: When enabled, edges are snapped to the nearest multiple of 45° (0°, 45°, 90°, 135°, 180°, etc.). When disabled, only orthogonal angles (0° and 90°) are permitted, forcing all diagonal edges to be converted into "staircase" patterns of horizontal and vertical segments.

How to adjust:

• Enabled: Better for buildings with diagonal walls or angled architecture
• Disabled: Creates pure rectangular geometries but may create jagged edges on diagonal walls
• ⚠️ Warning: Disabling this option on non-rectangular buildings will create pixelated/voxelized results

Diagonal Threshold Reduction

• Type: Decimal
• Default: 15.0
• Range: 1.0 - 20.0

What it does: Controls how strictly diagonal edges (45°) are treated compared to orthogonal edges.

Technical details: This is a division factor applied to the parallel threshold specifically for diagonal edges. The effective threshold for diagonals becomes parallel_threshold / diagonal_threshold_reduction. Lower values make the algorithm more strict about accepting 45° angles, while higher values are more permissive. Formula: diagonal_tolerance = parallel_threshold / diagonal_threshold_reduction. Example: With parallel_threshold=1.2 and diagonal_threshold_reduction=10.0 → diagonal tolerance = 0.12m

How to adjust:

• Lower (5.0-8.0): Very strict, diagonals must be nearly perfect 45° angles
• Medium (10.0-12.0): Balanced approach (recommended)
• Higher (15.0-20.0): Permissive, accepts approximate diagonals more easily
• If you see "staircase" edges on diagonals: Increase this value

Detect Circular Features

• Type: Checkbox
• Default: Enabled

What it does: Detects and preserves circular or near-circular shapes instead of converting them to polygons.

Technical details: Uses shape analysis to identify features with high circularity ratio. When detected, these features are preserved as rounded shapes rather than being regularized into polygons with many edges. Useful for silos, towers, rounded corners, or circular buildings.

How to adjust:

• Enabled: Preserves circular architecture (recommended for mixed building types)
• Disabled: Converts all shapes to angular polygons

Circle Threshold

• Type: Decimal
• Default: 0.9
• Range: 0.5 - 1.0

What it does: Defines how "round" a shape must be to be considered circular.

Technical details: Uses the isoperimetric quotient: circularity = (4π × area) / (perimeter²). A perfect circle has a value of 1.0. Only shapes with circularity above this threshold are treated as circles. 1.0 = Perfect circle only, 0.9 = Nearly circular (default, good balance), 0.7-0.8 = Loosely circular (may include rounded rectangles), 0.5-0.6 = Very permissive (risk of false positives)

How to adjust:

• Higher (0.95-1.0): Only perfect or near-perfect circles
• Lower (0.7-0.85): Accepts more rounded shapes
• Only active when "Detect circular features" is enabled

Align with Neighbors

• Type: Checkbox
• Default: Disabled

What it does: Analyzes nearby buildings and attempts to align edges with neighboring structures.

Technical details: For each building, the algorithm searches for neighbors within the specified distance, analyzes their edge orientations, and rotates/aligns the current building to match the dominant orientation of its neighbors. This creates visual coherence in dense urban areas where buildings share walls or follow street alignment patterns.

How to adjust:

• Enabled: Better visual coherence in dense urban areas (row houses, city blocks)
• Disabled: Faster processing, each building treated independently
• ⚠️ Warning: Significantly slower processing, recommended only for dense urban environments
• Performance impact: Can increase processing time by 5-10x on large datasets

Neighbor Search Distance

• Type: Decimal (meters)
• Default: 100.0
• Range: 10.0 - 500.0

What it does: Defines the search radius for finding neighboring buildings.

Technical details: When "Align with neighbors" is enabled, the algorithm creates a spatial buffer around each building and identifies all neighboring buildings within this distance. Only buildings within this radius influence the alignment calculation. Larger values consider more neighbors but increase processing time.

How to adjust:

• Smaller (50-100m): Local neighborhood alignment, faster
• Larger (200-500m): Broader area alignment, slower
• Only active when "Align with neighbors" is enabled
• Recommendation: Use 50-100m for residential areas, 100-200m for commercial districts

Max Rotation (°)

• Type: Decimal (degrees)
• Default: 10.0
• Range: 1.0 - 45.0

What it does: Maximum angle by which a building can be rotated to align with its neighbors.

Technical details: Limits how much the algorithm can rotate a building during neighbor alignment. This prevents over-correction where a building would be rotated too aggressively to match neighbors that have very different orientations. The algorithm calculates the dominant orientation of neighbors and rotates the current building toward that orientation, but never more than this maximum.

How to adjust:

• Lower (5-10°): Subtle alignment, preserves original orientation
• Higher (20-45°): Aggressive alignment, can significantly change orientation
• Only active when "Align with neighbors" is enabled
• Recommendation: Use 5-10° for most cases to avoid over-correction

Problem: Diagonal walls appear as "staircases"

Solution: Increase "Diagonal Threshold Reduction" to 15.0 or 18.0

Problem: Too many details are lost

Solution: Decrease "Simplify Tolerance" to 0.2-0.3

Problem: Irregular angles remain after processing

Solution: Decrease "Diagonal Threshold Reduction" to 8.0-10.0

Problem: Buildings are too "square" and unnatural

Solution: This is a limitation of the algorithm. Consider using the Polygon Smoother tool instead for organic architectures.

Problem: Processing is very slow

Solution: Ensure "Align with neighbors" is disabled unless specifically needed for dense urban areas.