Poly UV Contour Stretching Property Editor

Controls how a Contour Stretch UVs projection is calculated for a selection of polygons, and how the resulting UV coordinates correspond to the texture image.

To display: Click the icon of the PolyUVContourStretching operator under the appropriate texture projection’s node in the explorer.

Mute

When enabled, the contour stretch operation is temporarily disabled, or muted.

Method

Specifies how the polygon selection’s UV coordinates are calculated. Choose one of the following options:

Walking on the Mesh From Contours: calculates the UV coordinates by following the mesh as closely as possible from contour to contour, in both the U and V directions, and accumulating edge distances from the selection’s borders. This option will usually give the best results, particularly on complex meshes.

Spatial Distance from Contours: calculates the UV coordinates by travelling from border to border without trying to follow the mesh. This method gives fast results on simple meshes, and quick and dirty results on more complex meshes.

Walking NxM Regular Quads from Contours: calculates the UV coordinates by walking from border to border and trying to build parallel border lines to produce a grid-like structure. This is most effective for regular shaped NxM rectangular polygons, and may produce undesirable results when the mesh is irregularly shaped.

Projection on Surface Built from Contours: creates an internal parametric surface using the contours and borders of the polygon selection and then projects the polygon selection onto that surface to calculate its texture coordinates. This method is especially useful for bumpy, terrain-like surfaces.

Interior Smooth

Performs a simple smoothing operation on the internal points of the UV coordinate set (the contour is unaffected). The result is to spread the UV coordinates outward within their contour.

This is especially useful when the initial Contour Stretch projection has created undesired overlapping of UV coordinates.

Unlike a relax operation (see Relax Property Editor), which attempts to smooth the UV coordinates by linking tension in 2D and 3D space, Interior Smooth computations are done only in the UV domain.

Contour Control

Tension

When you apply a contour stretch projection, the UV coordinates typically occupy the entire UV domain in at least one direction, creating a square or rectangular UV set. Adjusting the Tension pulls the contour inwards towards the internal 2D representation of the 3D contour, creating a better correspondence between the two.

Tension is the master control for adjusting the contour. Once you’ve begun to adjust the tension, you can refine the adjustment using the Contour Smooth and Deviation settings.

Contour Smooth

Smooths the contour of the UV coordinate set so that it better matches the original 3D contour. This can help to smooth out areas of the UV coordinates that have been overly affected by changes to the Tension setting.

UV coordinates within the contour are not smoothed, but may be displaced based on changes to the contour.

Deviation

Controls the local deviation of the projection plane at each point on the 3D contour. A local projection plane is calculated for each contour point, and the Deviation value controls the “rotation” of that plane. This helps compensate for variations in the orientation of the 3D geometry that aren’t accurately reflected in the 2D UV coordinate representation.

For example, if you apply a contour stretch projection to the polygons on the forehead of a head model, the contour points closer to the top of the head are oriented differently than those closer to the face. Since a single plane of projection is not appropriate for all of these points, adjusting the Deviation will adjust the plane of projection at each point, creating a more accurate UV representation of the forehead.

Clamp

When enabled, the four corners of the UV coordinate set are pinned to the four corners of the UV domain. These corner points remain fixed in position even if other Contour Control adjustments pull the rest of the contour inward.

Corner UV Values

ShiftCorner

Shifts the position Contour Stretch projection’s start corner on the texture image. The net effect is to rotate the projection’s UV coordinates in a clockwise direction as the value increases.

SwapUV

Exchanges the U and V directions of the texture coordinates. The texture (if any) is flipped and rotated.

MaintainAspect

When enabled, the Contour Stretch projection’s UV coordinates on the texture image will, as much as possible, preserve the aspect ratio of the selected polygon on the object.

The aspect ratio of the polygon selection is calculated based on the U and V lengths of its contours, not the dimensions of the area that it occupies nor its bounding box.

U/V Min/Max

Controls the position of the Contour Stretch projection’s UV coordinates on the texture image. Min and Max values correspond to start and end positions in the U and V directions.



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