Houdini 22.0 Nodes Geometry nodes

UV Relax geometry node

Minimizes the distortion of UV parameterizations.

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Since 22.0

Overview

This node relaxes a UV parameterization to minimize the total distortion of the parameterization. It also resolves UV backfaces, where the orientation of the UV texture is opposite that of the polygon. This can be useful for improving the quality of UV maps generated by UV Flatten, which may typically have large amounts of distortion. Options to control the boundary behavior, the positions of pinned vertices, and the configuration of seam edges are also exposed.

The measure of distortion used is the symmetric Dirichlet energy. It is a measure of both the distortion from each primitive into UV space and the distortion of the inverse map (from UV space back into 3D space). In terms of the Jacobian of the deformation J the energy density is given by |J|^2 + |inverse(J)|^2.

Parameters

Group

A subset of primitives in the input geometry. Leave this blank to improve the distortion of the UV parameterization in all primitives in the input.

UV Attribute

The name of the UV vertex attribute to optimize.

Distortion Minimization

Solver Iterations

Number of iterations of UV relaxation to perform.

Pinned Vertices

A group of vertices whose UV coordinates are kept fixed throughout UV relaxation.

Pin UV Boundaries

When on, the positions of vertices on the boundary of UV islands will be fixed.

Seam Edges

This edge group determines additional edges in the UV parameterization to be cut open, allowing further distortion minimization.

Sew Edges

This edge group determines which UV island boundary edges, if any, will be sewn together. If an edge is in both this group and the seams group, it will be treated as a seam edge.

Scale

A multiplicative factor on the target area of the UV islands.

Layout Options

Pack Into

If UV boundaries are unpinned, UV islands may overlap during the relaxation process. The Layout Options can re-pack or the UV Layout can be used after.

None

Leaves the position of UV islands intact.

Rectangle

Repack the relaxed parameterization into a rectangle.

Packing Area

This section is visible when Pack Into is set to Rectangle.

Center

The center of the packing area in UV space.

Size

The width and height of the packing area, in UV units.

See also

Geometry nodes