2.3 GPU Volume Grid
Using the V-Ray Volume Grid on the GPU allows you to render volumetric effects such as fire and smoke, extremely fast.
- Go to Create Panel > V-Ray > and create a “VolumeGrid”
- Click somewhere close to the origin and pick one of the Cloud cache files from the “Asset” folder
- Start IPR
- You can control the color, opacity and other properties of the smoke through the rendering options of the “VolumeGrid”
- In “Smoke Color” rollout, change the “Constant color” to white
- In “Smoke Opacity” rollout, reduce the “Simple Smoke Opacity” quite a bit
- You can also reduce the “External Scatter Mult” to make the cloud a bit more contrasty
- Next you can experiment with the preview settings
- They are going to affect only the viewport appearance and not the rendering result of the cache
- When creating multiple copies you might want to reduce the preview voxels number for better viewport performance (Details Reduction)
- You can switch to the render camera and populate the sky with some clouds
2.3.1 Volume Grid Texture Steps
With V-Ray Next Update 1, you can also use the Volume Grid without needing to load in cache files. Instead, you can use a 3D Texture to create a volume, such as non-uniform fog, or textured details in the fog.
- Go to Create Panel > V-Ray and create a “VolumeGrid”.
- When prompted to load a cache file, click cancel.
- Next with the volume grid selected, go to the Modify Panel> Rendering > Volumetric Options.
- Expand the “Smoke Opacity” tab and set it to be based on a texture.
- Click on the texture slot and select a 3D texture - such as noise.
- Start IPR.
- Create an instance of the noise texture in the material editor to modify it.
- Decrease its size to something around 6.
- To add more contrast, you can also adjust the high and low thresholds of the noise texture.
- Finally set the noise type to fractal and its levels to 10.
- Stop the IPR.
- Next go to the “Layer Explorer” and make the “Geometry” layer visible.
- With the volume grid selected go to the main toolbar and right click on the scale icon.
- Set the scale to 25000%.
- Now switch to the render camera.
- Change the proportions of the volume grid from its "Grid" section.
- You can set it to roughly match the size of the green rectangle visible in the top viewport.
- Click on the "Decrease Resolution" button a few times until you end up with a few million cells.
- Once again start IPR.
- Now let’s change the color of the volume grid.
- From “Volumetric Options” set the color to be based on a texture.
- Drag and drop a copy of the texture used for the opacity in the color texture slot.
- Adjust its colors and continue tweaking the parameters of both noise textures until you are happy with the result.