Displacement | V-Ray GeomDisplacedMesh

This page provides information on the V-Ray GeomDisplacedMesh node, which controls displacement on meshes.

 

Page Contents

 

Overview

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Displacement mapping is a technique for adding detail to your scene geometry without having to model it first. The concept is very similar to bump mapping. However, bump mapping is a shading effect that only changes the appearance of a surface, while displacement mapping actually modifies the surface.

The attributes in this section affect V-Ray displacement and can be added to any polygonal mesh object.

 

 

 

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Main

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Texture – Specifies a displacement texture

Type – Specifies the mode in which the displacement will be rendered.

Normal – Takes the original surface geometry and subdivides its triangles into smaller sub-triangles which are then displaced. It can be applied for arbitrary displacement maps with any kind of mapping.
2D – Bases the displacement on a texture map that is known in advance. The displaced surface is rendered as a warped height-field based on that texture map. The actual raytracing of the displaced surface is done in texture space, and the result is mapped back into 3D space. The advantage of this method is that it preserves all the details in the displacement map. However, it requires that the object have valid texture coordinates. You cannot use this method for 3D procedural textures or other textures that use object or world coordinates. The displacement map can take any values.
Vector – If using a displacement texture that is not grayscale, V-Ray will convert it to grayscale before rendering the displaced geometry. This mode allows V-Ray to use the Red, Green, and Blue channels of the displacement texture to displace the geometry in the U and V directions in addition to the direction of the face normal.
Vector (Absolute) – A vector-type displacement mode in which the texture is interpreted as 0.5-based tangent space displacement map.
Vector (Object) – Only meaningful when a VRayPtex texture is used for displacement, where the texture values represent 0-based displacement in object space. If mesh information is stored in the Ptex file, V-Ray can also displace correctly mesh deformations.

Flip Green / Blue Channels –

Generate – Specifies how the resulting triangles of the displacement algorithm will be inserted into the rayserver.

On the Fly – Dynamic
Pre-Tesselated – Static

Amount –The amount of displacement for white areas of the displacement map. If Use Global Settings is enabled, this value is multiplied by the global displacement Amount option.  A value of 0.0 means the object will appear unchanged. Higher values produce a greater displacement effect. This can also be negative, in which case the displacement will push geometry inside the object.

Shift –Specifies a constant which will be added to the displacement map values, effectively shifting the displaced surface up and down along the normals. This can be either positive or negative. For more information, see the Displacement Shift example below.

Keep Continuity – When enabled, V-Ray will try to produce a connected surface. Use it when you get splits (usually around sharp edges) in the displaced geometry. For more information, see the Keep Continuity example below.

Water Level – Geometry below this displacement level threshold will be clipped away. This can be used for clip mapping a displacement map value below which geometry will be clipped. For more information, see the Clip Mapping example below.

Cache Normals – When enabled, V-Ray generates and saves information about the normal of each newly generated vertex. This requires additional memory but speeds up the shading calculations during rendering. Please see the Displacement tab to improve output result.

 

Bounds

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Use Bounds – When enabled, allows the user to set the minimum and maximum values for the displacement texture. For more information, see the Texture Boundaries example below.

Min/Max Bound – These two options allow you to specify custom boundaries for the displaced geometry when Use Bounds is enabled. By default is limited to values between 0 and 1.

Dicing

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Use Global Settings – When enabled, the global Displacement quality settings from the V-Ray Renderer will be used.

View Dependent – Determines if view-dependent tessellation is used.  When enabled, Edge Length determines the maximum length of a subtriangle edge, in pixels. A value of 1.0 means that the longest edge of each subtriangle will be about one pixel long when projected on the screen. When  View-dependent  is off, Edge length  is the maximum subtriangle edge length in world units.

Edge Length – The maximum length of a subtriangle edge after subdivision. This affects the degree of subdivision before displacement, which in turn affects the quality of the displacement itself. Each triangle of the original mesh is subdivided into a number of subtriangles. More subtriangles mean more detail in the displacement, slower rendering times and more memory usage. Less subtriangles mean less detail, faster rendering and less memory used. Units used for this parameter depend on the View Dependent parameter. For more information, see the Edge Length example below.

Max Subdivisions – Controls the maximum number of subtriangles generated from any one triangle of the original mesh. The square of this value is used. For example, a value of 256 means that at most 256 x 256 = 65536 subtriangles will be generated for any given original triangle. It is recommended that this value not be increased a great deal over the default value of 256. If you need to use higher values, it is better to first tessellate the original mesh itself into smaller triangles before starting the displacement process.

Tight Bounds – When enabled, causes V-Ray to compute more precise bounding volumes for the displaced triangles, leading to slightly better rendering times.

 

Subdivision

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Render As Subdivision –

Preserve Map Borders – Specifies how to handle subdivisions of UV coordinates at UV seams. The possible values are:

Not Set – The default value when the value has not been set.
None – UVs are always subdivided regardless of whether they are on a UV seam or not
Internal – Only preserve UVs if they are on an internal UV seam;
All – Does not subdivide UVs on UV seams.

 

Classic Catmull-Clark – When this option is enabled, V-Ray will use the Classic Catmull-Clark method for subdividing the mesh instead of the hybrid one used by default. This option should be enabled only if the mesh is composed entirely of rectangular faces or it will not work.

2D Settings

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Resolution – Determines the resolution of the displacement texture used by V-Ray. If the texture map is a bitmap, it would be best to match this resolution to the size of the bitmap. For procedural 2D maps, the resolution is determined by the desired quality and detail in the displacement. Note that V-Ray will also automatically generate a normals map based on the displacement map, to compensate for details not captured by the actual displaced surface.

Precision – Related to the curvature of the displaced surface; flat surfaces can do with a lower precision (for a perfectly flat plane you can use a value of 1), more curved surfaces require higher values. If the precision is not high enough you can get dark spots ("surface acne") on the displacement. Lower values compute faster.

Filter Texture – When enabled, the texture map will be filtered before the actual displacement takes place.

Filter Blur – Specifies the amount of blur that will be applied to the texture before the displacement takes place. 

Multi-Tile – Enables or disables support for tiled textures (UDIM/UVTILE) when generating 2d displacement.

 

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Example: Displacement Shift

 

Note that the Displacement Shift parameter is an absolute value in world units. If you change the Displacement Amount, you will probably need to adjust the Displacement Shift too.

 

 

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Example: Edge Length 

The image below was rendered with a Edges Map | VRayEdgesTex  in the Diffuse slot of the material, so you can see the original triangles of the mesh. Additionally, we turned on the Faceted option in the VRayMtl. Now, V-Ray will not only smooth the surface normals, but will also automatically apply a normals map that represents the normal of the perfect displaced surface, which will make the surface look a lot more detailed that it actually is.

View-dependent is turned on, and it refers to pixels in the original image, not the zoomed-in image you get with a blow-up rendering. This is why we were able to do a blow-up rendering to see the individual subtriangles better. Click the images for a larger view:

 

 

 

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Example: Keep Continuity

 

The Keep Continuity option is useful for objects with disjoint normals on neighboring triangles, usually because of different smoothing groups. In the middle image below you can see the edge splits produced by disjoint normals. Using the Keep Continuity option avoids this problem. This option will also help to produce a smoother result across material ID boundaries for objects with multiple materials.

 

 

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Example: Clip Mapping

Note: The Water Level parameter is also absolute in world units. If you change the Displacement Amount and/or Displacement Shift, you will probably need to adjust the Water Level to get the same effect. For this example, the Displacement Amount parameter is set to 5.0 and the Displacement Shift parameter is set to 0.0.

 

 

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Example: Texture Boundaries

This example shows a plane mapped with a displacement map that has negative values. With the default boundaries for the displacement (from 0 to 1) we are unable to see the geometry displaced in the negative direction. However, once we set Displacement bounds to Explicit and set Min value and Max value to -1 and 1 respectively, we can see the displaced geometry in both the positive and negative direction.

 

 

 

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Catmull-Clark – When this option is enabled, V-Ray will use the Classic Catmull-Clark method for subdividing the mesh instead of the hybrid one used by default. This option should be enabled only if the mesh is composed entirely of rectangular faces or it will not work.