Cut

The Cut tool allows you to remove or extract portions of visible surface(s) using a variety of region-of-interest (ROI) selection methods. This is essential for trimming unwanted parts of a surface, isolating specific regions, or preparing surfaces for further processing.

Medical Disclaimer

This tool is provided for research and educational purposes only. Any clinical or diagnostic use requires proper validation in accordance with applicable regulations.

Overview

The Cut tool operates on all visible surfaces, making it easy to trim multiple objects simultaneously with a single operation. You define the region to affect using ROI tools, then choose whether to remove that region or extract it as a new surface.

Unlike the Clip tool which uses infinite planes, the Cut tool offers more flexible ROI shapes including freehand drawing, geometric primitives, and 3D selection regions.

Interface

Operation

Select what happens to the selected region:

Operation	Description
Cut	Remove the selected ROI portion from the visible surface(s)
Retain	Remove the selected portion and create a new surface object from it

ROIs Mode

Choose the category of ROI selection tools:

Mode	Description
Quick	Basic 2D selection tools (freehand, rectangle, polygon)
Advanced	Extended selection tools with additional options
Primitives	3D geometric shapes (box, sphere, cylinder)

Quick Mode Tools

Tool	Description
Freehand	Draw a freehand outline in the viewport
Rectangle	Draw a rectangular selection region
Polygon	Click points to define a polygonal outline
Lasso	Freehand selection with automatic closure

Advanced Mode Tools

Advanced mode provides the same tools as Quick mode with additional options:

Option	Description
Selection mode	Add to or replace current selection
Target	Apply to active surface or all visible surfaces
Depth selection	Select visible faces only or include occluded faces

Primitives Mode Tools

Tool	Description
Box	Define a 3D box region using corner handles
Sphere	Define a 3D spherical region with center and radius
Cylinder	Define a 3D cylindrical region

Primitive ROIs can be positioned and resized interactively in the 3D view.

Actions

Button	Description
Reset	Reset the ROI placement to the bounding box of visible surfaces
Apply	Execute the cut operation

Cut vs. Clip vs. Editor

Understanding when to use each cutting tool:

Scenario	Cut	Clip	Editor
Trim using freehand shapes	✓
Trim using infinite planes		✓
Trim using 3D primitive shapes	✓
Create closed (capped) cuts		✓
Delete individual triangles			✓
Extract region as new surface	✓	✓	✓
Apply to multiple surfaces at once	✓	✓	✓

Typical Workflows

Trimming Excess Geometry

To remove an unwanted portion of a surface:

1. Make only the surfaces you want to cut visible
2. Open the Cut tool
3. Select Cut operation
4. Choose an appropriate ROIs mode and tool
5. Define the region to remove
6. Click Apply

Extracting a Region

To isolate a specific portion as a new surface:

1. Open the Cut tool
2. Select Retain operation
3. Define the region to extract using ROI tools
4. Click Apply

The selected region is removed from the original surface and added as a new surface object.

Trimming with a 3D Box

To remove everything outside (or inside) a bounding region:

1. Select Primitives mode
2. Choose the Box tool
3. Position and resize the box using the handles
4. Ensure the box encloses the portion you want to keep or remove
5. Select Cut to remove or Retain to extract
6. Click Apply

Precise Cutting with Polygons

For precise cuts along specific boundaries:

1. Select Quick or Advanced mode
2. Choose the Polygon tool
3. Click to place vertices along the desired cutting boundary
4. Double-click to close the polygon
5. Apply the cut

Best Practices

1. Hide unaffected surfaces: The Cut tool operates on all visible surfaces. Hide surfaces you don't want to modify.

2. Use Retain for safety: If you're unsure about the cut, use Retain to preserve the removed portion as a new surface.

3. Reset for primitives: Use the Reset button to initialize primitive ROIs to the bounding box of your surfaces—a good starting point for adjustments.

4. Consider closed clipping: If you need the cut surface to remain watertight, use the Clip tool with the Closed clip option instead.

5. Fill holes after cutting: Cutting creates open boundaries. Use Fill Holes if you need a closed surface.

6. Use appropriate mode:

   • Quick for fast, simple cuts
   • Advanced for precise control over selection behavior
   • Primitives for 3D volumetric selections

Keyboard Shortcuts

Key	Action (varies by ROI tool)
Escape	Cancel current selection
Enter	Complete selection (polygon tool)
Double-click	Close polygon and apply

See Also

• Clip - Trim surfaces using infinite planes with optional capping
• Editor - Manual triangle-level editing
• Fill Holes - Close holes created by cutting
• Boolean - Compute geometric Boolean operations