Houdini 20.5 Nodes Geometry nodes

UV Pelt 2.0 geometry node

Relaxes UVs by pulling them out toward the edges of the texture area.

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Since 14.0

UV Pelt operates very similar to how a tanner creates a pelt. Cuts are made to the geometry to produce a surface topologically equivalent to a disc. The boundaries of this surface are connected to a frame and stretched out.

Any closed face can be used as a frame for the pelt. A circle is used if no frame is specified. A hint polygon is used to specify which section of the geometry to pelt after performing the cuts. The longest boundary of the section containing the hint polygon is the one connected to the frame. The frame is parameterized to the range [0, 1). The boundary points are spaced around the frame at distances in the frame’s parameterization that are proportional to the edge length with the neighboring boundary point.

The best way to visualize the effects on UVs is in the UV view. To change a viewport to show UVs, click the View menu in the top right corner of a viewport and choose Set View ▸ UV viewport, or move the mouse over the view and press Space + 5.

You can also visualize UV attribute values in the 3D view using an attribute visualizer.

UV Pelt creates the UV vertex texture attribute if it does not already exist.

Note

UV Pelt only operates on polygons. Other geometry type such as Bezier and NURBS surfaces can be converted to polygons using a Convert operation prior to applying UV Pelt.

Using UV Pelt

  1. Click the UV Pelt tool on the Texture tab.

  2. Select the edges that will form the boundary of the pelt.

    Tip

    You can easily select loops of edges using the Edge Loop tool.

  3. Press Enter to unwrap your selection.

You can scale the pelt by increasing the Boundary Springs in the parameter editor. You can also use UV Edit to move the UVs.

Parameters

UV Attribute

The name of the texture coordinate attribute to pelt, defaulting to uv.

Edge Cut Group

Edges to cut.

Pelting Method

Every edge is modeled as a spring. The points are placed to the position that minimizes the spring energy. The choice of Pelting Method affects the strength of individual springs.

Spring Relaxation

Uses spring weights based on length of the edges and the areas of a the faces incident to the edge.

Tutte Barycentric

Uses unit weights except at boundary points. This means that every point is placed at the mass center of its neighbors. The mass of the boundary points is given by the spring parameter. The main advantage of this method is that it always guarantees a one-to-one parametrization (with no inverted triangles) for convex boundaries.

Discrete Harmonic

Uses a weight assignment scheme known as discrete harmonic method which minimizes angular distortion.

Create Output Group

Indicates a primitive group should be created for the polygons making up the pelt.

Output Group

Name of the primitive group to create.

Pelt

Iterations

Specifies the number of iterations of the algorithm for solving the UV positions.

Boundary Springs

The strength of the springs connecting the pelt boundary to the frame.

Stiffness Attribute

Specifies an attribute of the input geometry’s points that will be used to scale the strength of the springs connected to the point.

Hint Primitive

The primitive specifying which section of the geometry forms the pelt.

Frame

Frame

The primitive to use for the frame.

U From

The attribute of the frame used for the U coordinate.

V From

The attribute of the frame used for the V coordinate.

Use Range

Indicates the UV coordinates should be moved to the ranges specified with U Range and V Range.

U Range

The location of the left and right edges, respectively, of the texture

V Range

The location of the bottom and top edges, respectively, of the texture

Orientation

Specifies where on the frame to position the first boundary point (the boundary point closest to the hint polygon).

Weight Attribute

Specifies an attribute of the frame’s points that will guide the process of connecting boundary points to the frame.

See also

Geometry nodes