---
title: "Volumetric Rendering In-Depth"
canonical: "https://documentation.chaos.com/space/VC4D/116855379/Volumetric%20Rendering%20In-Depth"
format: markdown
---
This page provides some useful tips for rendering volumetric effects.

## **Volumetric vs Volumetric Geometry mode when rendering on the CPU**

---

The Volumetric Geometry mode is provided as an option for the following reasons:

1. Generation of Render Elements for compositing - for a complete list of the supported **Render Elements** in both Volumetric and Volumetric Geometry mode, please check the [Render Elements](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116855112) page.
2. Blending of multiple atmospheric effects in the scene - e.g., you use an [Aerial Perspective](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116850807) and a  [Volume Grid Simulation](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116856912) - if the mode is set to Volumetric, one would be entirely behind the other in the rendered image.

Limitations:

1. The Volumetric Geometry mode does not work with Probabilistic Volumetrics.
2. The Volumetric Geometry mode tends to be slower to render. Ideally, you should work in Volumetric mode all the time and switch to Volumetric Geometry only when generating the Render Element passes.
3. The Approximate and Approximate+Shadows Scattering options under Rendering → Smoke Color are not supported in Volumetric Geometry mode. It would default to Disabled scattering.
4. You may need to increase the V-Ray Settings → Overrides → Materials → Max. Transparency Levels option, which slows down rendering. When rendering in Volumetric Geometry mode, procedural geometry made up of multiple transparent layers is generated at render-time. Think of it as sprites used in video games - a sequence of slices facing the camera.

> Macro (ui-text-box)
> 
> When rendering with **V-Ray GPU**, the Render Mode does **not** matter - Render Elements are generated, and the rendering speed is the same in both the Volumetric and Volumetric Geometry modes.

## **AUR vs. VDB Cache Format**

---

![image](media://6108b78f-936c-43fd-a283-c6a7367c3e85)


![image](media://3a269473-e8f6-4795-8d89-93560dbf30a8)


## **Core Volumetric Shader Settings**

---


---



---


![image](media://c3cd3277-c2a2-4f5c-8d1b-bcb9aaf0f734)


> Macro (ui-text-box)
> 
> When rendering with **V-Ray GPU**, the Use Light Cache option is ignored entirely - the Volume Grid Light Cache is a CPU-only 'hack' used to speed up CPU rendering.


---



---


![image](media://58f4e8d3-9d59-4935-99df-b5a30447cf6e)


![image](media://0ea65354-c999-4f3d-950a-62deda34b45b)



---


![image](media://afb12850-0ab4-49f7-8dc0-624800b7d2fa)


![image](media://4bc79623-9610-4c48-b64a-4da10f0b07b8)



---



---



---



---


![image](media://842802ae-656e-4b40-8243-9136f3479929)


![image](media://fffd5d1d-2e27-4ed3-8a72-8c8571a8e49d)



---


![image](media://842802ae-656e-4b40-8243-9136f3479929)


![image](media://2c2472dd-06bd-4530-a150-e5c75d52455b)



---


![image](media://2221659b-b4fb-4766-86ef-f393f49d5c0b)



---


## **Smoke Opacity and Probabilistic Volumetrics**

---

![image](media://16073792-aeea-41f8-82bc-4ee7afa5be7c)


![image](media://9ced7cdb-a082-459e-8d21-2af2f8e3fa92)



## **V-Ray Adv vs. V-Ray GPU Rendering of Volumetric Effects**

---

![image](media://7be7dc96-4322-4575-89d0-f508c5d8e995)


![image](media://a4ff42df-6005-4d50-b062-b736d6294224)