This page provides a Displacement tutorial for V-Ray for Houdini.
Overview
In this step-by-step tutorial, we show how to set displacement to an object. In the first part, we apply displacement using the Displacement Properties assigned directly to the geometry.
Then, we go through a second case, where different displacement maps are assigned to different parts of an object. We use the V-Ray GeomDisplacedMesh node attached to a material in order to achieve the goal.
Object Displacement
Create and enter a Sphere.
Change the Primitive type to Polygon Mesh and set the Rows and Columns to 32.
Connect the uvtexture SOP and then turn the Texture Type to Polar.
We connect the Null SOP only for clarity in the node scheme.
In the mat network, create V-Ray Material Builder and dive into it.
Set the Diffuse color to 0.5; 0.5; 0.5 and Roughness to 0.25.
In the Render tab of the Sphere, assign the material we just created.
And here is the rendered result - a simple sphere:
Let's add the displacement now.
Select the sphere and from the V-Ray shelf, choose the Subdiv Props. Note that in earlier V-Ray versions the Subdiv Props option is called Displacement Properties.
This way, we add control over the object's displacement.
In Texture, set the path to the displacement texture of your choice. Set the value of the Amount accordingly.
And here is how the render looks like with the added displacement:
Different Displacement Maps for Different Parts of an Object
Different displacement maps can be set for different parts of an object. To do that, we have to add displacement per material and then assign those materials over the different members of the geometry. Let's see how this works.
In a new file, create a sphere and enter its node.
With Alt+drag-and-drop, copy the sphere two more times. This way, we create three different objects considered as one geometry item.
Add UVTexture SOP for each of the three spheres. With the help of transform SOP nodes move them along.
Create a Merge SOP that will bring all of the nodes into one whole geometry. The Null SOP is again added for clarity of the scheme.
This time, leave the Material in the Render tab of the geometry empty.
Do not add displacement properties from the Subdiv Props button (respectively the Displacement Properties button for earlier V-Ray versions), as this will be done for each material separately.
In the mat network, create V-Ray Material Builder, just as we did previously. Set the diffuse Color to 0.5; 0.5; 0.5 and Roughness to 0.25.
From the TAB menu > V-Ray > Geometry, choose V-Ray Displacement. Attach it to the Surface input option of the vray_material_output node.
Do this for two more materials, assigning the desired textures to be used as displacement.
Back in Geometry network, add the material SOP for each of the objects. Assign the respective already created materials from the mat network.
Render. The result is three simple smooth surface spheres:
In order to get a correct render, the geometry has to be "packed" before assigning the materials. That's why we set a pack SOP before the material SOP. The geometry has to be packed when using this workflow because V-Ray deals with Displacement at the object level. V-Ray for Houdini exports each packed primitive as a separate object, providing you with the ability to partition the SOP-level geometry into individual shapes to assign different displacement maps to.
This way V-Ray can apply the correct displacement for each object.
Assigning Object Properties SOP and/or Displacement materials works with packed geometry. It is not expected to work with packed fragments.
Now the render result shows the three spheres with three different types of displacement in one geometry item, just as intended.
