Houdini 20.5 Nodes Geometry nodes

Refine geometry node

Increases the number of points/CVs in a curve or surface without changing its shape.

On this page

You can localize the effect to a subsection of the input geometry.

You can also use this node to decrease the number of points/CVs within a given tolerance, as a simplistic but fast method of data reduction.

= Using Refine == (includeme)

The Difference Between Refinement and Unrefinement

Refinement and unrefinement work both on faces (polygons, Bezier curves and NURBS curves) and surfaces (primitive meshes, Bezier surfaces and NURBS surfaces). To unrefine a face or a surface you need to specify a parametric interval (not just a single value as in refinement). This allows you to unrefine primitives within arbitrary intervals, either locally or globally. For example, to unrefine the whole primitive choose 0 and 1 as the two parametric boundaries; [0,0.5] will unrefine only the first parametric half of the primitive.

The interval boundaries are given by the First/Second U/V fields. Since refinement does not need an interval, the Second U/V fields are disabled by default.

The Tolerance control is only available for unrefinement, and not for refinement. Refinement does not need tolerances because it generates a curve or a surface that is mathematically identical to the original. Unrefinement, however, may tend to smooth out (or “melt”) the original in a given area. In short, unrefinement is lossy; refinement isn’t.

Parameters

Group

Subset of geometry to refine.

First U

Starting location in U [0,1].

Second U

Ending location in U [0,1].

U Divisions

Number of divisions to create in U.

First V

Starting location in V [0,1].

Second V

Ending location in V [0,1].

V Divisions

Number of divisions to create in V.

Refine

NURBS Count U, V

Number of knots to insert in each location /refinev when refining NURBS geometry. /refineu

Uniform Domain Lengths

Refine splines at equal intervals.

Uniform Arc Lengths

Each refinement is done at the center of the maximum knot spans (splines) or edge length (polygons).

Unrefine

NURBS Count U, V

Number of knots to remove from NURBS geometry at each location. /unrefineu /unrefinev

NURBS Tolerance U, V

Only remove knots that do not change the /tolu resulting shape by more than this distance. /tolv

Subdivide

Uniform Domain Lengths

Divides splines at equal intervals.

Uniform Arc Lengths

Each divide is done at the center of the maximum knot spans (splines) or edge length (polygons).

Examples

BasicRefine Example for Refine geometry node

This example contains a few methods of how the Refine SOP can be used to add or remove detail from many types of surfaces.

See also

Geometry nodes