This page provides information on the V-Ray Displacement rollout that is part of the V-Ray Geometry Properties.
Displacement mapping is a technique for adding detail to scene geometry without having to model it. The concept is very similar to bump mapping. However, bump mapping is a shading effect that only changes the appearance of a surface in renderings, while displacement mapping actually modifies the surface.
To access this rollout, you must first add the V-Ray Geometry Properties to a mesh item.
UI Path: ||Select mesh|| > Properties viewport > V-Ray Geometry Properties tab
Example: Displacement vs. Bump Mapping
This example shows the difference between bump mapping and displacement mapping. Notice that bump mapping doesn't change the round outline of the sphere or its shadow, where displacement deforms the object's outline.
V-Ray Displacement Parameters
Enable displacement – Turns displacement mapping on or off and is enabled by default.
Displacement Amount – Specifies the strength of the displacement. A value of 0.0 means the object will appear unchanged. Higher values produce a greater displacement effect. This value can also be negative, in which case the displacement will push geometry inside the object. Changing this value usually means that Displacement Shift should also be adjusted.
Displacement Shift – Specifies a constant in world units which will be added to the displacement map values, effectively shifting the displaced surface up and down along the normals. This value can be either positive or negative. For more information, see Example: Displacement Shift.
Keep Continuity – When enabled, V-Ray will try to produce a connected surface. Use it when splits occur in the displaced geometry (usually around sharp edges). The Keep continuity option is useful for objects with disjoint normals on neighboring triangles, usually because of different smoothing groups. This option will also help to produce a smoother result across material groups boundaries when multiple materials are used to shade different polygons of an object. For more information, see Example: Keep Continuity.
Enable water level – When enabled, clips the surface geometry in places where the displacement map value is below the threshold specified with the Water Level field.
Water Level – Sets the clipping amount in absolute world units. For more information, see Example: Water Level.
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.
Object Space Displacement – Enabling this option switches from World Space to Object Space. This makes a difference when the object with displacement has a scale other than 100%. When enabled, the mesh item's scale will affect the amount of displacement. Used only when doing 3D Displacement.
Use Bounds – When enabled, controls texture boundaries. Allows Min/Max Bound values to be set so that negative displacement can be achieved. For more information, see Example: Texture Boundaries.
Min/Max Bound – Specifies custom boundaries for the displaced geometry when Use Bounds is enabled. By default, the boundaries are limited between 0 and 1. These parameters are available only when Use Bounds is enabled.
Vector displ. type – When Vector Displacement effect is set up in the Shader tree, this option specifies how the the Red, Green and Blue channels of the displacement texture will be used to displace the geometry in the U and V directions in addition to the normal of the face.
Tangent – Interprets the texture as 0.5-based tangent space displacement map.
Tangent (absolute) – Used to match Mudbox displacement maps.
Object – This type is only meaningful when Ptex displacement textures are used with the V-Ray PTex texture, 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 mesh deformations correctly. Object-space Ptex vector displacement only works for subdivision surfaces when V-Ray Subdivision is enabled.
2D Displacement – When enabled, 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 has valid texture coordinates. This method cannot be used for 3D procedural textures or other textures that use object or world coordinates. The displacement map can take any values.
Resolution – Determines the resolution of the displacement texture used by V-Ray. If the texture map is a bitmap, it is 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 – This value is related to the curvature of the displaced surface. Flat surfaces can use a lower precision value, and more curved surfaces require higher values. A perfectly flat plane can use a value of 1. If the precision is not high enough, dark spots (or "surface acne") can appear on the displacement. Lower values compute faster.
Tight bounds – When enabled, V-Ray computes more precise bounding volumes for the displaced triangles, leading to slightly better rendering times.
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 displacement takes place.
Example: Displacement Shift
Displacement Shift = -5.0
Displacement Shift = 0.0
Displacement Shift = 5.0
Example: Keep Continuity
Keep Continuity disabled
Note the edge splits at sharp angles.
Keep Continuity enabled
No more edge splits at sharp angles.
Example: Water Level
For this example, Displacement Amount is 5.0 and Displacement Shift is 0.0.
Water Level = 0.0 (no clipping)
Water Level = 1.25
Water Level = 2.5
Water Level = 3.75
Example: Texture Boundaries
This example shows a plane mapped with a displacement map that has negative values. With the default boundaries for the displacement, we are unable to see the geometry displaced in the negative direction. However, once we set the custom boundaries to -1 and 1 we can see the displaced geometry in both the positive and negative direction.
Min Bound = 0, Max Bound = 1
Min Bound = -1, Max Bound = 1