This page provides information about the Override Material in V-Ray for SketchUp.
Overview
The Override Material is a utility material provided with the V-Ray renderer. It allows a surface to look different depending on whether it is seen through reflections, refractions, or GI. With this material you can get a fine control over the color bleeding, reflections, refractions, and shadows of the objects.
Image by Linda Ferroni demonstrating the reflect material override option.
UI Paths
||V-Ray Asset Editor|| > Materials (right-click) > Override
||V-Ray Asset Editor|| > Create Asset (left-click) > Materials > Override
Parameters
Base Material – The material V-Ray uses while rendering the object.
Shadows – The material that V-Ray uses to render shadows cast from the object.
Reflection – The material V-Ray uses to render the object with, when the object is seen in reflections. For more information, see Using the Reflect Material example below.
Refraction – The material V-Ray uses to render the object with, when the object is seen in refractions. For more information, see Using the Refract Material example below.
GI – The material V-Ray uses when calculating the GI solution. For more information, see Using the GI Material example below.
Environment – The texture that V-Ray uses instead of the scene environment maps for this specific material.
Example: Using the GI Material Override
This example shows how the use of a GI material override affects the rendering.
This simple interior scene represents a room lit by two rectangle VRayLights - one hidden top light and another back fill light - as well as by three disc VRayLights for the pendant lamps above the sinks.
A wooden Generic material from the Chaos Cosmos library is applied on the floor, and a default Generic material with Diffuse Color (128, 128, 128) is applied on the rest of the scene objects, except for the glass objects (mirror and pendant lamp plafonds).
In the first image, it is visible that all walls, objects, and the ceiling are rendered in some light brown color, despite having a light-gray material assigned to them. This is due to the color bleeding, generated by the GI calculations.
In the second image, the scene is rendered with an Override V-Ray material containing the wooden Generic material as a base and the default Generic material plugged into the GI slot. The rest of the scene objects keep the default gray Generic material. So now V-Ray knows that while calculating the GI it has to use the material used as GI override (in this case: Generic with Diffuse color (128, 128, 128) and during rendering it uses the Base material (in this case: the wooden Generic ). The result of that is quite different from the previous render as the Color Bleeding is gone. Of course this depends entirely on your choice for the GI material override. For instance, if you had chosen a bluish colored material, the final result would also be tinted slightly to blue, like in the first render with the pale brown colors.
For a much more complex scene, with lots of different geometry, shaders, textures, etc., using the V-Ray Override material can be very helpful.
Example: Using the Reflect Material Override
The scene used in the following examples is very simple. It contains four boxes, a light source, and a studio type environment. Each box has an Override material assigned, but only the Base Material is active. The rendered boxes are all one and the same in their diffuse and their reflections as well. As you can see now, each of the boxes has a different material assigned in their Override Reflect Material. The first one has a red diffuse color, the second ones have green, and the third one has blue. V-Ray uses those materials, when the objects are seen in reflections. In our scene, the environment is actually a reflective surface, so the boxes are being reflected. On the other hand, you can also notice that the base material of the boxes is also reflective (Fresnel type), and the middle boxes are seen with their Override Reflect material in the right box.
Example: Using the Refract Material Override
The next render is even more complex as the Override Refract Material of the boxes is activated as well. From left to right follow: a cyan, a purple and a yellow diffuse color. Those materials are set so that when seen through refraction, V-Ray will consider and render the objects with them. As you can see the Reflect materials are still affecting the render image. If you take a closer look at the lens' edges you will notice the green reflection, which is actually the reflect material of the middle boxes. While V-Ray had been tracing the rays on the lens' surfaces, those polygons on the edges had first captured a reflection, so that's why there are green traces.
Binding
Texture – Allows the user to display the selected texture in the viewport. Keep in mind that procedural textures are not displayed.
Override Control
Can be Overridden – When disabled, the material is not overridden by the Material Override option in the Render Settings.