(Available from version 2025.3 - 16.08 / 2026.1 - 26.02)
---------- Range Remap mode -----------
Octane Volume normally uses the specified VDB file as 'Filename mode'
This simply send the VDB filename to the Octane engine, and the engine will get data from the specified channels (Absorption, Emission, etc), and scale those with the matching scale values (Absorption scale, Emission scale, etc..).
In some case, the scaling is not enough as the data may contain low values that create noise, or you may wish to eliminate too low or too high values to adjust the final result.
The Range Remap mode allows to remap the channel values more precisely, and to ignore values outside a specified range.
This can result in a more crispy effect, with full black around the fire/smoke/etc.
When enabled with the 'Enable Range Remap' checkbox, this mode will read the VDB channel data and re-create all volume data, and send it to the Octane engine.
For example, if a VDB has a temperature channel in the range [300,2000], it can be re-mapped from [350,2000] to [0,1], and values bellow 350 will be set to 0 if the 'Zero min' option is enabled.
The Old Max value can also be set lower than the actual data (for example 1800 would set all values higher than 1800 to 1800, or 0 if 'Zero Max' is enable)
Use the 'Channel values' button to read all the grid values of the current channel, to see what are the actual lowest and highest values.
Setting the 'New Min', 'New Max' to [0,1] also help with the channel scale, that can remains around the 1.0 value, and the Volume Medium settings can also use Density, emission power etc with values around 1.0 instead of very small values like 0.001 .
Samples:
OctaneVolume_Range_Remap.zip --- Sample :
Range_Remap\fire25_10_NoRemap_vs_remap_mx18.max
Note that with no remap (OctaneVolume_001), Absorption scale is set to 0.001 and Emission scale to 0.002
This is to reduce the temperature channel values (range 300,2000)
The medium used (Map #3_NoRemap) has a Texture emission (Map #4_NoRemap) with Power set to 0.46
With remap (OctaneVolume_002), as the range options is set from [305,1892] to [0,1], Absorption and Emission scales are set to values around 0.5.
And the medium used (Map #3_remap) has a Texture emission (Map #4_remap) with Power set to 100
--- Sample:
Range_Remap\fire25_11_vdbs_vs_Phx_mx18.max
The remap range for PhoenixFDFire001 is set the same as OctaneVolume_002.
Both use the same volume Medium.
Note that only Phoenix frame 21 (PhoenixFDFire001_0021.aur) is provided.
---Sample: Color gradient.
Remaping to a [0,1] range makes it more easy to apply a color gradient:
Note that the Emission scale is animated to simulate an engine power variation.
--------- Composite Channels -----------
The composite channels mode can combine 3 single float channels to a vector3 channels.
There are 2 vector3 channels that can be created this way, named '_vec3_1' and _vec3_2'
This is specially designed to be used with the 'Std Volume medium', that can select those vector3 channels for Emission, Scatter, etc..
The typical use case is for RGB color channels, when they are only available as separate R, G and B channels.
Another usual vector3 channel is the velocity, but the Octane Volume already has an option to select velocity as 3 separate channels (x,y,z), or a single vector3 channel, so there is no need to use this Composite mode for velocity.
To use the composite channels, make sure 'Enable Range Remap' is turned on in Range Remap Settings
Samples:
The VDB used has 3 channels for the color: one for each color components : ColorR_phx, ColorG_phx, ColorB_phx.
Those 3 channels are set in the 'V3 channel 1 (x,y,z)' parameters, so the combined vector3 channel is available as '_vec3_1' in the Map #13 medium (Std Volume medium).
Note:
Those VDB files have been created with Phoenix FD, with RGB channels.
(specifying .vdb in the output rollup: Simulation Cache Save Path: $(scene_path).vdb)
See the related post 'Phoenix FD Fire color channel' : viewtopic.php?t=83095
The resulting VDBs have the up axis as Y instead of Z, so the OctaneVolume object has been rotated to compensate.
(There may be some options in Phoenix FD to export with Z as the up axis..)
In this case, the combined rgb channel '_vec3_1' is used as the 'Scatter color channel' of the Std Volume medium.
---------- Extra channels (Std Volume medium) ----
A set of 5 extra channels can be specified, in addition to the 4 channels assigned to Absorption, Emission, Scatter and Velocity.
This ensure that those channels are loaded and selectable by the Std Volume medium for any of the medium effects (Density, Scatter, Transparency, Emission, Temperature).
--------- Motion blur enabled -----
When a velocity is specified and the current camera has Motion blur enable, the volume grid will have a motion blur effect.
This can be disabled / enabled with the 'Motion blur enabled' checkbox.
Sample:
-The velocity is currently only working when set as a vector3, with the Remap mode disabled.
----- Display settings ------
The settings to display the volume channels in the 3dsMax viewport is now per channel.
This allow to match the Remap values per channel (eg set Cell value min / max same as Old Min / Max).
Different Display percent and step count can also be set for each channel.
Note that the cloud point data used for the 3dsmax viewport display are stored in cache files.
The location of those cache files can be set in Render settings / Support / Common Scene Collection Settings.
The default location is in the same folder as the vdb files, in a sub folder 'OVdbPreview' : 'VDB Preview cache location' : 'VDB sub folder'
A new location type, 'Scene sub folder' can be used instead, if you wish to use different display settings using the same VDB files with different scenes.
---- File sequence updates ----
Issues with some filenames have been fixed.
Filenames with multiple extensions is now correctly handled (eg PhoenixFDFire001_0000.aur.vdb)
The 'Sequence digits' is automatically changed to avoid incorrect settings and allow the use of all available vdb files.
To disable animation, the value 0 should be typed instead of using the arrows (as the value 1 is usually re-set to 2 or more).
