InternalUnion¶

NOTE: Performance optimization – the overlapping-geometry check is now skipped for very large meshes (> 2000 faces) to avoid stalls. Loose parts and separate volumes detection still apply.

Intelligent boolean union for merged objects with loose parts or overlapping geometry.

Overview¶

InternalUnion automatically detects and resolves complex geometry issues in merged objects, applying appropriate boolean union operations to create clean, solid meshes. Perfect for CAD imports and complex assemblies that need to be unified into single solid objects.

Location¶

Shift+W Menu → CLEANING → InternalUnion

Features¶

Intelligent Detection¶

Automatic analysis of mesh complexity and structure
Smart button activation - only available when needed
Multiple detection methods for different geometry types
Progress feedback during analysis and processing

Three Detection Strategies¶

Loose Parts Detection¶

Completely disconnected mesh islands
Separate objects joined with Ctrl+J
Classic boolean union approach with separation

Separate Volumes Detection¶

Connected but distinct volumes (like overlapping cubes)
Minimal vertex connections between major geometry sections
Advanced connectivity analysis through face relationships

Overlapping Geometry Detection¶

Coincident faces with similar normals
Superimposed geometry requiring internal cleanup
Internal boolean operations without object separation

Automatic Processing¶

Context-aware method selection based on geometry type
Fallback strategies if primary method fails
Comprehensive cleanup after union operations
Error handling with graceful recovery

ALT+Click Enhancement¶

Hold ALT while clicking to automatically triangulate faces after union: - Perfect for game development workflows - Consistent triangle topology for export - High-quality triangulation using Beauty method - Combined operation - union + triangulation in one step

How to Use¶

Basic Union¶

Select a merged object with multiple parts/volumes
Open Shift+W → CLEANING
Click InternalUnion (button activates automatically when needed)
Review the results - object becomes a unified solid

Union with Triangulation¶

Select a merged object with multiple parts/volumes
Hold ALT and click InternalUnion
Object is unified AND triangulated automatically
Perfect for game asset preparation

Detection Examples¶

Scenario 1: Loose Parts¶

Original: 3 separate cubes joined with Ctrl+J
Detection: "Found 3 loose parts"
Method: Separate → Boolean Union → Join
Result: Single solid cube

Scenario 2: Overlapping Volumes¶

Original: 3 cubes duplicated and positioned to overlap
Detection: "Found 3 separate volumes"
Method: Separate → Boolean Union → Join  
Result: Complex unified solid

Scenario 3: Internal Overlaps¶

Original: Geometry with coincident internal faces
Detection: "Found overlapping geometry"
Method: Internal boolean operations
Result: Cleaned internal structure

Smart Button Behavior¶

The InternalUnion button intelligently activates based on mesh analysis:

Button Enabled When:¶

Multiple loose parts detected
Complex overlapping geometry found
Separate volumes within single object
Mesh complexity suggests union would be beneficial

Button Disabled When:¶

Simple geometry (less than 8 vertices)
Already unified mesh structure
Single connected volume with no overlaps
No benefit from union operations

Processing Methods¶

Method 1: Separate + Boolean + Join¶

Used for: Loose parts and separate volumes 1. Separate by loose parts in edit mode 2. Apply boolean union modifiers between parts 3. Delete temporary objects and keep result 4. Clean up geometry with merge doubles and normal recalculation

Method 2: Internal Boolean Operations¶

Used for: Overlapping geometry 1. Internal intersect boolean operations 2. Resolve coincident faces and overlapping regions 3. Clean internal structure without object separation 4. Optimize resulting topology

Method 3: Hybrid Approach¶

Used for: Complex mixed cases 1. Analyze geometry type and complexity 2. Apply most appropriate method automatically 3. Fallback to alternative if primary method fails 4. Ensure successful union through multiple strategies

Post-Processing Cleanup¶

After union operations, InternalUnion automatically: - Merges duplicate vertices (0.0001 threshold) - Recalculates normals for consistent shading - Removes loose geometry (vertices, edges) - Triangulates faces (if ALT was held) - Reports changes made to the mesh

Results Feedback¶

Success Messages¶

"InternalUnion completed: Successfully unified 4 loose parts using boolean union"
"InternalUnion completed: Resolved overlapping geometry using internal boolean operations"
"InternalUnion completed: Successfully unified 3 separate volumes + triangulated faces"

Status Updates¶

"Analyzing geometry..." - Initial detection phase
"Found X loose parts - applying separate & boolean union..." - Processing loose parts
"Found overlapping geometry - applying internal boolean union..." - Processing overlaps
"Cleaning up geometry..." - Final cleanup phase

Use Cases¶

CAD Import Cleanup¶

Multiple parts imported as single object
Assembly components that need unification
Overlapping volumes from boolean operations
Complex mechanical parts with internal structure

Game Development¶

Asset optimization for real-time rendering
LOD preparation with simplified geometry
Collision mesh creation from complex models
Triangle-based export requirements

3D Printing Preparation¶

Solid object creation from separate parts
Internal void elimination in complex models
Manifold mesh generation for reliable printing
Volume optimization for material efficiency

Architectural Modeling¶

Building component unification
Complex intersection resolution
Structural element merging
Simplified representation of detailed assemblies

Tips¶

Button auto-disables when no union is needed - this is normal behavior
Try Default/Aggressive Clean first for topology issues
Use ALT+Click when you need triangulated output
Works with multiple selected objects - processes each separately
Large models may take time - progress feedback keeps you informed
Undo available if results aren't as expected

Troubleshooting¶

Button is grayed out: - This is normal - means your mesh doesn't need union - Try with objects that have multiple disconnected parts

Boolean operation fails: - Complex geometry sometimes fails with Exact solver - Tool automatically tries Fast solver as fallback - Consider using TopoCleaner first to clean problematic geometry

Unexpected results: - Some complex overlaps may require manual boolean operations - Use Undo (Ctrl+Z) and try different approach - Consider separating parts manually for more control