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Voxel Grid - Specifies the Phoenix Simulator or V-Ray Volume Grid from where the voxel grid data will be read.

Render Presets – – Opens a menu for loading and saving different presets. The following options are available:

Step % | rendstep – Specifies the ray marching step of the camera rays as a percentage of the cell size. As the renderer traces rays through the Simulator, this value controls how often to read information from the Grid. If this value is more than 100, some cells will start getting skipped and artifacts may appear. Usually you don't need to lower this below 90%, unless you use render curves or texture maps for the Fire or Smoke opacity or color - in these cases you might need to lower the step in order to capture the details which are smaller than a voxel, otherwise these details will either be skipped or will render very noisy. However, decreasing the step will make the render slower.

Shadow Step % | rendshadstep – Specifies the ray marching step of the rays used to evaluate the lighting (shadow rays) as a percentage of the Cell Size. Usually, this value can be higher than Step %, as generally shadows will not need so much detail. Increasing the Shadow Step % will also speed up rendering performance, particularly with dome and area lights.

Border Fade (units) | borderFade – Makes the content near the Grid's boundaries more transparent to prevent sharp edges from being rendered. This parameter controls how far from the boundaries the transparent effect should start, in Scene Units.

Sampler Type | sampler – Determines the blending method between adjacent grid voxels. Used to balance between rendering speed and quality.

Box – Displays voxels as cubes. There is no blending between neighbor voxels. This is the fastest mode.
Linear – Linear blending occurs between neighbor voxels to smooth out the fluid's look. Sometimes this mode may unveil the grid-like structure of the fluid. Up to 20-30% faster than the Spherical option.
Spherical – Uses special weight-based sampling for the smoothest looking fluid. With increasing resolution, the visual advantage of this method over the Linear method becomes less noticeable.

Motion Blur Multiplier | mbmult – Specifies a multiplier that affects the strength of the motion blur. This value can be a negative number. 

Volume Volumetric Motion Blur | volMoblurMethod – Specifies the type of Motion Blur that will be used.

Ray-traced – The default Volumetric Motion Blur method.
Grid-based – This method could be used instead of the default Ray-traced method in cases when you need more visible motion blur streaks, especially with faster moving fluids. The method requires a pre-pass and uses more memory.

Velocity Texture | rendVelTexture – Specifies a custom texture used for motion blur when rendering Fire/Smoke simulations. The colors of the texture represent the velocity direction for each cell, similar to how Vector Displacement textures are evaluated. Every Simulator cell receives a certain color from the texture, treats it as a direction vector and stretches the contents of the Simulator along to produce motion blur. This parameter can be used with a V-Ray User Color texture for motion blur in a single direction (e.g. by setting the color to (0, 1, 0) for motion blur in the +Z axis), or any other Maya texture applied as a 3D projection. The texture overrides the Velocity grid channel even if available in the cache files. Note that the Y and Z components of the velocity vectors are flipped - they are sampled respectively from the Blue and Green color values of the texture.  

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Displacement Amount | rendDispl, rendDisplEnbl – Specifies a displacement strength multiplier.

Texture | rendDisplFine – Specifies the displacement map. Depending on the Type option selected, a monochrome map or a color map could be required. If a colored map is specified when a monochrome map is needed, the strength of the displacement is determined by the total intensity of the color. If a monochrome map is specified when a vector map is needed, the entire displacement will point in a single direction. For more information on texture mapping in Phoenix, please check the Texture mapping, moving textures with fire/smoke/liquid, and TexUVW page.

Type | rendDispltSurf – Specifies the displacement technique.

Gradient driven – Requires a monochrome texture map. The displacement amount is the texture's brightness at each point. Each point of the fluid is shifted along the gradient of the Surface channel. This means that each point in space could have a different displacement direction. This method is suitable for smoke and fire.
Surface driven – Requires a monochrome texture map. The displacement amount is the texture's brightness at each point. Each point of the fluid is shifted along the normal of the point's projection on the isosurface of the fluid's Surface channel. The texture is also sampled at the projection point. Unlike the Gradient driven displacement, this ensures that all points above or below the fluid surface will be displaced in the same direction, and so displacing Fire/Smoke simulations produces better results that are more similar to displaced solid geometry surfaces. However, the Surface driven method is slower than Gradient driven.
Vector – Requires a colored vector texture map (with negative and positive values). The point is shifted by the texture color, interpreted as a 3D vector. This displacement mode is intended to be used with the Phoenix Ocean Texture but can be used with any other vector displacement texture.
Advection – Requires a colored 0.0-based vector texture map (with negative and positive values). A very similar method to Vector, but does not produce grainy structures for fire and smoke. Can be combined with the Phoenix Grid Texture, with its Channel set to Velocity, to produce render-time gridless advection.