Merge Overlapping Polygons

Combines overlapping entities on visible layers into merged polygon results. In LinkCAD 11, the tool opens as Merge Shapes from Tools → Boolean Operations → Merge Overlapping Polygons.

When to Use

• To simplify geometry before export
• To create clean outlines from overlapping fills
• Before de-embed or hole extraction operations

Options

Option	Description	Default
Keep original inner boundaries (slow!)	Preserve original internal polygon boundaries in the result instead of merging them away	Off
Flatten Hierarchy	Flatten cell references before merging so referenced geometry participates in the same merge operation	Off
Only merge polygons	Skip non-polygon entities instead of exploding them into polygon outlines before the merge	Off
Fill Rule	Select how overlaps and winding are interpreted: Non-Zero or Even-Odd	Non-Zero
Draw generated holes using…	Choose Cut-lines in re-entrant polygons, Sliced simple polygons, or Extract holes as polygons	Cut-lines in re-entrant polygons
Arc Precision	Precision value and units used when non-polygon shapes are converted before merging	32 segments/360°
Apply To	Apply to All Visible geometry or only the current Selection	All Visible

See Merge Hole Output Modes for a visual explanation of each hole output representation.

Legacy label mapping

LinkCAD 11 label	Legacy label	Meaning
Only merge polygons	Don’t explode complex shapes	When enabled, the merge operates only on entities that are already polygons. Non-polygon shapes such as paths with width, arcs, circles, NURBS, and text are left untouched.
Extract holes as polygons	Omit cut-lines in re-entrant polygons	Holes are emitted as separate polygons instead of being connected back to the outer contour with cut-lines.

How It Works

1. Optionally flattens the hierarchy when Flatten Hierarchy is enabled
2. Groups visible or selected entities by layer
3. Converts non-polygon shapes to polygon outlines unless Only merge polygons is enabled
4. Computes the union of overlapping polygons within each layer using the selected fill rule and hole mode
5. Replaces the originals with the merged result

Before:

┌───────┐
│   A   │
│   ┌───┼───┐
│   │   │   │
└───┼───┘   │
    │   B   │
    └───────┘

After:

┌───────────┐
│           │
│  A ∪ B    │
│           │
└───────────┘

Technical Notes

• Non-overlapping polygons on the same layer are left unchanged
• The merge operation preserves the layer assignment
• This is equivalent to a boolean OR (union) per layer
• Hole representation behavior is documented in Merge Hole Output Modes
• In practical outputs such as photomask data, cut-lines and sliced boundaries are typically superimposed; illustration gaps are visual aids only
• Extract holes as polygons can create separate hole polygons that overlap source contours; use a cut-line or sliced-polygon mode when the downstream format requires holes embedded in the same contour
• Processing time depends on the number of polygons and their complexity