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This page provides information on the Volumetric Grid Input.

 

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Overview


This page contains information on input channels that can be loaded and re-mapped for a VRayVolumeGrid. The input file loaded for the Volumetric Grid must be generated from the source program with channels mapped in such a way that VRayVolumeGrid can read them correctly. The input file is selected when the VRayVolumeGrid is first created, or in the Input rollout on the Modify panel.

 

Supported Channels


VRayVolumeGrid is based on Phoenix FD, and in its core it supports the following channels:

Liquid/Temperature
Smoke
Velocity
Speed
RGB
Fuel

Different applications use different channels and names for them. When loading f3d/vdb files, VRayVolumeGrid tries to automatically make the conversion to the supported channels. If a channel is not mapped by default, a channel can be manually set in the Input rollout on the Modify panel by clicking the Browse [...] button under Preview & Render Cache Path and choosing 3rd Party Channel Mappings from the pop-up menu. Note that this option appears on the pop-up menu only if no input file has been selected yet.

 

Manually equalizing the render settings with FumeFX


Certain FumeFX settings can be optimized to keep render times as low as possible: 

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  • Make sure the Step % value on the Rendering rollout matches the corresponding FumeFX step parameter. A smaller Step % value will lead to longer render times.
  • In the Fire rollout of the Volumetric Options, select Fuel as the channel the fire color is based on, as this is FumeFX's Fire channel after importing the .f3d file. For Fire Opacity Mode, choose the Use Own Opacity option and carefully duplicate the fire color and fire opacity diagrams from FumeFX.
  • Please note that VRayVolumeGrid does not support the Fluid Mapping option in FumeFX.
  • VRayVolumeGrid has the option to illuminate the other objects in the scene automatically by using emissive lights. This will increase render times. In order to turn it off and keep only the illumination on the volumetric itself, set the Light Power on Scene value in the Fire rollout to 0.0 and set Self-shadowing in the Rendering rollout to Grid-based. You can also speed up the calculations of self-illumination by reducing the Light Resolution (%) value in the Rendering rollout.

 

Distributed Rendering with VRayVolumeGrid


A common problem with setting up distributed rendering for VRayVolumeGrid is that the rendering process might look for the cache files in a local machine directory. However, at the start of a network render, the scene file is copied to all render machines on the network to a new location, e.g. C:\Users\user\AppData\Local\backburner\Jobs\, while cache files are not automatically sent to the host machine. The cache files are not sent because they could potentially overload the host's disk space if they are very large, and also because in many cases not all of them are actually used in the rendering. This is why when the rendering begins, if the hosts are looking for the cache files in a directory that was originally on the local computer, the cache files won't be found.

The solution is to move the cache sequence to a shared folder on the network, or a mapped network drive, and set its path in the Input rollout using a network-visible UNC input path (a path that starts with \\). You can also browse from the Input rollout's path options.

if the path points to a drive on the local computer rather than a UNC path, a message will appear: "You are using local machine Input path with distributed rendering!".