Simple smoke – Uses the smoke channel with a predefined analytical formula.
Temperature – Uses the temperature channel.
Smoke – Uses the smoke channel.
Speed – Uses the magnitude of the velocity channel.
Texture – Uses an external texture map.
Fuel – Uses the fuel channel.
? – Opens the help documents.
Texture | ttxt – If the Based on parameter is set to Texture, or if Modulate is enabled, this slot specifies the texture to be used.
Scale Opacity by Scene Units | alphaunitscale – When enabled, the opacity per unit length will remain constant when changing the Grid resolution. Therefore, the larger the unit scale it, the denser the smoke will appear in renders and vice versa. This option is Off for imported Field3D and OpenVDB cache files. Note: When disabled, Phoenix caches simulated at higher grid resolution will appear more opaque than the same simulation at a lower resolution.
Minimum Visible Opacity | skiptransp – If the opacity of a voxel is below this specified value, the voxel will not be shaded at all. Increase this value to speed up rendering. Decrease it if parts of the smoke are too transparent and start disappearing in the render.
Optimize Big Volumetric Grids | optvolpass – Helps render scenes with caches above 25 Million cells faster. If using Progressive rendering or if there are a lot of simulators in the scene, and you want your render to start without a pre-pass, you might want to disable this option. Please note, that this option is ignored when rendering with V-Ray GPU.
Opacity Diagram | transp_t, transp_s, transp_v, transp_f – This diagram specifies the transparency/opacity at given point as a function of the channel selected in the Based on parameter. The selected channel's data range is denoted by a blue-green line.