Delete surface node

Deletes input geometry by entity number, bounding volume, primitive/point normals, and/or degeneracy.

All Parameters Local variables Example files

See also: Blast, Dissolve, Group, Unpaste

In addition to simply deleting unwanted parts of a model, this operator is useful for culling primitives from very dense geometry to speed up cooking of nodes downstream.

This operation can also delete profile groups (for example, 0.5 1.2-3.9) and mixed groups (for example, 0 0.5 4-12 1.2-3.9). It can also delete entire paste hierarchies or pasted surfaces, causing the remaining hierarchy to update. By deleting the root of a paste hierarchy, the whole hierarchy becomes undone.

Using Delete

  1. Select the object at the object level or components of the object at the geometry level.

  2. Click the Delete tool on the Modify tab.

Note

This tool is mapped to the Del key.

Parameters

Note

This node deletes entries in the Group field and any polygons matching the criteria in the Operation, Entity, and Geometry Type fields.

Group

Subset of the input geometry to delete from.

Operation

How the rules below affect the geometry.

Delete selected

Delete the geometry that matches the rules below.

Delete non-selected

Delete the geometry that doesn’t match the rules below.

Entity

Points

Delete points.

Primitives

Delete primitives.

Geometry Type

Type of geometry to delete.

Number

Enable

Turns on the controls for this tab and allows you to delete by point/primitive numbers.

Operation

How to choose which points/primitives to delete.

Delete by pattern

Delete points/primitives whose numbers match a pattern string.

Delete by range

Delete points/primitives whose numbers fall within a certain range, and/or delete every few points/primitives.

Delete by expression

Evaluate an expression for each point/primitive and delete it if the expression returns true.

Filter Expression

(When Operation is “Delete by expression”) Evaluates this expression for every point/primitive and, if the expression is true, deletes the point/primitive.

You can use all the local variables of the Point and Primitive operations in this expression.

Pattern

(When Operation is “Delete by pattern”) Deletes points/primitives that match this pattern.

Start/End

(When Operation is “Delete by range”) The range of geometry to be deleted.

Select of

(When Operation is “Delete by range”) Deletes every (number in the left field) points/primitives for every (number in the right field) points/primitives in the input.

Bounding Volume

Enable

Turns on the controls for this tab and allows you to delete entities inside a bounding volume.

Bounding Type

Shape of bounding volume.

Bounding box

Delete points/primitives within a bounding box.

Bounding sphere

Delete points/primitives within a bounding sphere.

Size

Size of the bounding volume.

Center

Center of the bounding volume.

Normal

Enable

Turns on the controls for this tab and allows you to delete entities based on their normals.

Direction

Delete points/primitives with normals pointing in this direction. Use the Spread angle

Spread Angle

Angle of deviation from specified direction for which geometry will be deleted.

Backface from

Specifies a camera. Polygons that face away from the camera are deleted.

Degenerate

Enable

Turns on the controls for this tab and allows you to delete degenerate entities.

Delete Degenerate Primitives

Remove repeated references of points and vertices within faces and then delete all degenerate primitives.

Delete Zero-Area Faces

Delete faces with no surface area (that is, a face whose points are all in a line).

Treat Open Faces as Closed

Consider open faces as if they were closed when deciding to delete zero-area faces.

Tolerance

Precision of algorithm used to compute degeneracy and colinearity.

Delete Unused Groups

Remove any groups that are left empty after deleting points/primitives.

Keep points

By default, if you delete a lot of polygons, the points that are no longer in use are also deleted. Turning on Keep Points will keep these points floating in space.

Local variables

N

The number minus one of points or primitives, depending on the “Entity” choice.

Example files

DeleteDemo

$HFS/houdini/help/examples/nodes/sop/delete/DeleteDemo.cmd

Load | Launch

This example demonstrates how the Delete SOP is used to remove specified geometry from a scene.

Geometry may be deleted by Point or Primitive Numbers, by Group, or by position within a Bounding Box.

DeleteFan

$HFS/houdini/help/examples/nodes/sop/delete/DeleteFan.cmd

Load | Launch

The Delete SOP can be used to delete primitives through various methods.

Primitives can be deleted using a pattern range to create interesting objects, such as the fan in this example.

Usages in other examples

Example name Example for

Attrib Transfer surface node

Load | Launch

Spring surface node

Load | Launch

Cloth Create Seam surface node

Load | Launch

Triangulate 2D surface node

Load | Launch

Skin surface node

Load | Launch

Skin surface node

Load | Launch

Dop Import surface node

Load | Launch

Poly Loft surface node

Load | Launch

Point surface node

Load | Launch

Particle Fluid Sink dynamics node

Load | Launch

Particle Fluid Sink dynamics node

Load | Launch

Field Force dynamics node

Load | Launch

Reference Frame Force dynamics node

Load | Launch

Smoke Object dynamics node

Load | Launch

Smoke Object dynamics node

Load | Launch

RBD Glue Object dynamics node

Load | Launch

Particle Fluid Emitter dynamics node

Load | Launch

Particle Fluid Emitter dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Object dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Particle Fluid Solver dynamics node

Load | Launch

Wire Solver dynamics node

Load | Launch

Fluid Object dynamics node

Load | Launch

Follow particle node

Load | Launch