This page provides a guide on rendering an Ambient Occlusion pass in V-Ray for Nuke and using it with the V-Ray Blend Material.
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In this first section, we set up a VRayDirt node and connect it to the diffuse channel of a VRayMtl, which will be used temporarily to tune-in the AO settings before later use as a mask.
1. Create a VRayDirt texture.
2. Create a VRayMtl, name it VRayMtl_TestAO_Material and then connect the VRayDirt texture as its diffuse input.
3. Connect the VRayMtl_Test_AO_Material to the img input of the geometry within the scene.
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4. Currently at the default VRayDirt settings, there are not a lot of dark areas to later use to blend the two materials. So using the test VRayMtl we have set up so far, the VRayDirt texture can be tuned to reach the look desired to act as that blending mask when we eventually use the VRayMtlBlend. For tuning, it is easier if the viewer in Nuke is set to the diffuse channel.
In the examples below, the VRayDirt texture has been tuned to give it a darker and broader output, by using a large Radius of 1000 and a high Distribution value of 75 (which tightens the dark areas). Also, the Subdivs have been raised to 8 so that the resulting texture is not overly noisy.
For a full explanation of all the parameters of the VRayDirt texture, please see the Occlusion or Dirt Map page. |
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In this section, we learn how to use the AO pass as a mask for a VRayMtlBlend to control blending between two materials.
1. Create a VRayMtlBlend material and connect the VRayDirt texture as a mask.
2. Create a VRayMtl material, name it VRayMtlRust, and connect the B input of the VRayMtlBlend material.
3. Create a VRayTexNoise texture and connect it to the diffuse input of the VRayMtlRust material. This acts as a basic rust color and gives some mild variation to the diffuse channel.
4. Create a VRayMtlCarPaint material, name it VRayMtlCarPaint, and connect the A Input of the VRayMtlBlend material.
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In this section we learn how to add some variation to the VRayDirt which is being used as a blend control mask for the VRayMtlBlend and its two materials.
1. Create a VRayTexNoise texture and connect it to the Occluded Color channel of the VRayDirt.
2. Ensure that Color 1 of the VRayTexNoise texture is set to black and that Color 2 of the VRayTexNoise texture is set to white.
3. Change the Type in the VRayTexNoise texture to Fractal, with Iterations set to 2, and Size set to 10.
4. Render the image.
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