Relax threshold angle to avoid false positive corner detection in STL file

[weiliangjin2021]

Greptile Overview

Updated On: 2025-10-30 23:56:51 UTC

Greptile Summary

This PR increases the default angle_threshold in CornerFinderSpec from 0.1π to 0.25π (π/4) to reduce false positive corner detection when processing STL files.

Key changes:

• Updated CORNER_ANGLE_THRESOLD constant from 0.1 * np.pi to 0.25 * np.pi in tidy3d/components/grid/corner_finder.py:18
• Updated all JSON schemas (Simulation, EMESimulation, ModeSimulation, TerminalComponentModeler) to reflect the new default value
• Added breaking change entry in CHANGELOG.md noting that angle_threshold in CornerFinderSpec now defaults to pi/4
• Properly categorized this as a breaking change affecting the microwave and smatrix plugins

Technical context:
The angle threshold determines when a vertex qualifies as a corner. A vertex is considered a corner if the angle spanned by its two edges is larger than π minus the threshold value. The previous threshold of 0.1π (18°) was too sensitive, causing false positives when detecting corners in STL files. The new threshold of 0.25π (45°) is more conservative and will only detect vertices as corners when the angle deviation from straight is more pronounced.

Confidence Score: 5/5

• This PR is safe to merge with no significant concerns
• The change is straightforward and well-implemented. It updates a single constant and ensures all related schema files are synchronized. The change is properly documented as a breaking change in the CHANGELOG. All modifications are consistent across files, and the new default value (pi/4) is reasonable for corner detection in geometric processing.
• No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
tidy3d/components/grid/corner_finder.py	5/5	Changed default angle threshold constant from 0.1π to 0.25π (line 18) to reduce false positive corner detection
CHANGELOG.md	4/5	Added breaking change entry for angle_threshold default change to pi/4, moved from wrong section

Sequence Diagram

sequenceDiagram
    participant User
    participant CornerFinderSpec
    participant LayerRefinementSpec
    participant GridSpec
    participant Simulation
    
    User->>CornerFinderSpec: Create with default angle_threshold
    Note over CornerFinderSpec: angle_threshold = 0.25π (NEW)<br/>previously 0.1π
    
    User->>LayerRefinementSpec: Configure with corner_finder
    LayerRefinementSpec->>CornerFinderSpec: Use corner detection
    
    User->>Simulation: Create with layer_refinement_specs
    Simulation->>GridSpec: Generate grid with layer specs
    GridSpec->>LayerRefinementSpec: Apply layer refinement
    LayerRefinementSpec->>CornerFinderSpec: Find corners on 2D plane
    
    CornerFinderSpec->>CornerFinderSpec: _filter_collinear_vertices()
    Note over CornerFinderSpec: Filter vertices where<br/>angle <= π - angle_threshold<br/>(now π - 0.25π = 0.75π)
    
    CornerFinderSpec-->>LayerRefinementSpec: Return corner coordinates
    LayerRefinementSpec-->>GridSpec: Apply corner-based refinement
    GridSpec-->>Simulation: Generate refined grid

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Diff Coverage

Diff: origin/develop...HEAD, staged and unstaged changes

• tidy3d/components/grid/corner_finder.py (100%)

Summary

• Total: 1 line
• Missing: 0 lines
• Coverage: 100%