Combine polygon meshes using booleans

Boolean operations in Maya describe features that determine how existing shapes interact with each other. For example, you can use the volume of one shape to sculpt another. They can be very powerful for modeling shapes that would otherwise be very difficult to model using other techniques.

Maya provides three boolean operations:

Boolean operations are very useful for trimming objects.

Boolean operations generate a new shape node. If you keep construction history, the original shapes can still be selected in the Channel Box, Hypergraph, or Outliner and edited, with the boolean result automatically updating. You can even change which boolean operation to use to combine the objects.

To combine two meshes with a boolean operation

  1. Select the meshes.

For the Difference operation, select the mesh you want to subtract from first.

  1. Select one of the boolean actions in the Mesh > Booleans submenu.

The faces of the objects are now connected and both original meshes act as one single object.

You can select the original objects using the Outliner, Hypergraph, Attribute Editor, or Channel Box. As long as construction history is on, when you edit the originals, the boolean result updates automatically.

For example, you can subtract a sphere from a cube using the Difference operation, then animate the original sphere to create an interesting effect:

Troubleshooting the polygon boolean operations

Boolean operations don’t work as expected

Boolean operations may sometimes produce unexpected results if the original objects are not closed volumes, or if they contain nearly coincident vertices. Other conditions to note include:

For example, to select zero area faces:

- Select the meshes.

- Choose Select > Select Using Constraints.

- Set Constrain to All Next

- Expand the Geometry and Area sections.

- Turn on Activate and set Min to 0 and Max to 0.0001.

- You can now enlarge them or remove the faces.

If you want to remove zero area faces or zero length edges altogether, use the Mesh > Cleanup feature to remove them prior to using the Booleans.

Maya runs out of memory when using the boolean operations

Using booleans on large polygonal objects is a memory intensive operation. Maya can run out of memory if this operation is performed many times on large polygonal objects.

To reduce the possibility of running out of memory, keep the undo queue length small or flush the undo queue every now and then when performing boolean operations on large polygonal objects.

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