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This page contains information about the V-Ray TexCurvature node.

Overview

V-Ray Curvature is a texture that effectively samples the underlying mesh for curves. A region around each shaded point gets sampled with additional rays (similar to V-Ray Dirt), and all additional normals are averaged to get a "smooth" normal at the original point. This normal is used to compute the color, which depends on the Mode of the map. The parameters should be adjusted by trial and error since they generally depend on the scale used, hence the defaults might not be appropriate in some cases.

V-Ray for Houdini > V-Ray Curvature > Dragon_Curvature_map_preview_both.jpg

Main

Mode – Switch between respective modes. See the Curvature Modes example below.

Legacy – Does not distinguish if the mesh is curving outward (convex) or inward (concave) but instead takes into account only the amount of overall curvature.
Convex – Generates a grayscale based on the mesh's outward curve.
Concave – Generates a grayscale based on the mesh's inward curve.
Both – Generates a red-green gradient based on both the mesh's convex and concave. Red corresponds to the mesh's convex and green corresponds to the mesh's concave.

Radius – Controls the factor which determines the radius that the curvature traces. Can be used to match curvature between big and small objects.

Sample Spread – Controls the radius of the sampled region.

V-Ray for Houdini > V-Ray Curvature > Hou19_VRay6_Curvature_Main.png

Output

Color Min – Specifies the minimum output color value for the most concave area (the dents in the mesh). Default value is 0 - completely black.

Color Max – Specifies the maximum output color value for the most convex area (the peaks in the mesh). Default value is 1 - white.

Gain – Multiplies the output values.

Lift – Uniformly lightens the output values.

Gamma – Applies gamma correction to the output values.

Pivot – Pivots the value to the gamma correction (output values equal to the pivot value are left unchanged).

Clamp – When enabled, clamps the Color Min and Color Max values in [0,1] range (negative values are output as 0 and values above 1 are being output as 1).

V-Ray for Houdini > V-Ray Curvature > Hou19_VRay6_Curvature_Output.png

Options

Ignore Bump – When enabled, excludes Bump maps from V-Ray Curvature computations.

Subdivs – Controls the number of samples around each shaded point.

V-Ray for Houdini > V-Ray Curvature > Hou19_VRay6_Curvature_Options.png

Example: Curvature Modes

V-Ray Blend material (with mixed Copper and Patina materials) is applied to the geometry. V-Ray Curvature map is used as the blend amount. The Gain is set to 5.5 and the Gama - to 0.1. All other parameters are left at their default states.

Note that the Both mode outputs a red and green color gradient instead of a black and white one. Using it as a blend amount for the V-Ray Blend material produces color blended materials. To avoid this, we use the Red and Green components of the V-Ray Curvature map separately to generate two monochromatic masks using Color Correction maps. This allows the generated red-green gradient to be used as a grayscale blend amount, like in all other Curvature modes. In this setup an additional (third) Dark Patina material is used, which appears in the most concave parts of the model. In addition the Gama is set to 1.5 for more pleasant results.

V-Ray for Houdini > V-Ray Curvature > Dragon_Curvature_map_preview_legacy.jpg

Legacy

V-Ray for Houdini > V-Ray Curvature > Dragon_Curvature_map_preview_convex.jpg

Convex

V-Ray for Houdini > V-Ray Curvature > Dragon_Curvature_map_preview_concave.jpg

Concave

V-Ray for Houdini > V-Ray Curvature > Dragon_Curvature_map_preview_both.jpg

Both