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This page provides information on the Output rollout.
Overview
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The Output rollout holds The Output rollout holds the controls for the simulation result.
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UI Path: ||Select PhoenixFDSim|| > Attribute Editor > Output rollout |
Parameters
Output Path
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When you start a simulation, the simulator will typically output an entire animation sequence, which is saved onto your hard drive by default. That sequence is saved as individual files, called caches, which contain raw simulation data for each timeline frame.
The Output rollout lets you set the save path for the cache files, manage what data is written to those cache files, and determine their compression.
Specifically, the cache data consists of grids and particles, which describe the fluid’s behavior. Grid Channels and Particle Channels are written to each cache file, which represent the properties of the simulated fluid at that frame.
In the Output rollout, you can choose which Grid Channels and Particle Channels to export to the cache files, based on your needs. The values for those exported channels will then be contained in each of the voxels in the simulation grid.
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When simulating fire or smoke, you could export Grid Channels such as Smoke, Temperature/Liquid, Velocity, RGB and so forth. For example, to simulate multiple colors of smoke, you would want to export the Grid RGB Channel. That way, if each of your Fire Sources emits a different color of smoke, each Source's RGB color information would be saved to the simulator's cache files. |
Meanwhile, for Liquid simulations, Phoenix can simulate several particle system types: Liquid, Foam, Splash, Mist and Wetmap particles.
Each of these particle systems contains Particle Channels, or fluid properties, for each particle. These channels include Position, Size, Age, ID, Velocity and so forth, which you can choose to write to the cache files, depending on your needs.
Grid Channels such as Temperature/Liquid and Velocity are then built from the simulated particles, and exported to the cache files in the form of a voxel grid.
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Exporting the Grid Temperature/Liquid Channel will automatically convert Liquid particles to a grid during export, which is why they can be rendered as a mesh and shaded using standard materials. In addition, the Liquid mesh can also be previewed in the viewport. Note that only Liquid particles can be automatically converted to a grid. The other particle systems (e.g. Foam, Splash, Mist etc.) are exported only as particles, and must be shaded using the Particle Shader. |
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UI Path: ||Select PhoenixFDSim|| > Attribute Editor > Output rollout |
Parameters
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Output Path
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$(work_path) – $(data_dir)/$(scene)_Phoenix_frames/$(nodename)_####.aur $(data_ | |||||||||||||||||||||||||
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$(work_path) – $(data_dir)/$(scene)_Phoenix_frames/$(nodename)_####.aur $(data_path) – $(data_dir)/$(scene)_Phoenix2_frames/$(nodename)_####.aur If you are transferring your scene and assets between Windows and Linux, prefixing your path with the $(workspace) or $env(<variable_name>) macros can make it possible to use the same scene without any manual modifications to the cache path. #### is the frame number formatted with at least as many digits as the hash signs. If the frame digits are less than the hashes, the number is padded with zeroes to the left. As an example, the following table shows how different numbers of hash signs affect the formatting of different frame numbers.
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Example: Particle compression artifacts
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Anchor OutputChannels OutputChannels
Output Grid Channels
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Fluid properties are written inside Grid Channels. Here you can choose which Grid Channels will be exported to the cache files when running a simulation. Each channel stores a type of value, such as Temperature/Liquid, Smoke, RGB, Velocity and so forth, with its own range of possible values that is most efficient for that specific channel type (see the Grid Channel Ranges). Phoenix determines the fluid’s behavior at a given time, based on the content of these Grid Channels. |
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Note that the Choose which simulation channels will be saved to the created cache files. The more channels are used, the slower the simulation runs and the larger the output files are. While scrolling the timeline, you can check which channels are present in the loaded cache file for the current frame, from the Cache File Content section section in the the Simulation rollout. Note Also note that in the case of FLIP / Liquid simulations, currently currently only the liquid Liquid particles can be automatically converted to a grid during export, while all the other systems (e.g. Foam, Splash, etc.) are exported only as particles. |
Grid Temper./Liquid | outTemp outTemp – If this is a fire/smoke simulation, exports the Temperature channel. If it's a liquid simulation, exports the liquid amount which is needed so that you can render the Liquid as a mesh and also preview it as a mesh in the viewport.
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Solid Voxels – Exports the solid voxels as smoke. Voxels covered by many obstacles contain more smoke.
Divergence Symm – Exports the negative divergence of each voxel.
Divergence Smooth – Exports the blurred negative divergence of each voxel.
Vorticity – Exports the length of the curl of each voxel. Can be used for whitewater shading.
Vorticity Smooth – Exports the blurred length of the curl of each voxel. Can be used for whitewater shading.
Velocity Gradient – Exports the length of the gradient of the velocity field.
Injector – Exports the pressure term created by sources in Inject mode or formed during the simulation.
Liquid Surface – Exports the surface created by the simulation.
Solid Geom Type – Exports the internal geometry type in each voxel.
Hydrostatic Pressure – Exports the pressure of the liquid at each voxel due to the effect of gravity.
Voxelization Issues – Exports voxels where the solver would produce wrong results during simulation. Such voxels are near overlapping triangles, inverted normals, open edges or other geometry issues.
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Solid Geom Type – Exports the internal geometry type in each voxel.
Hydrostatic Pressure – Exports the pressure of the liquid at each voxel due to the effect of gravity.
Voxelization Issues – Exports voxels where the solver would produce wrong results during simulation. Such voxels are near overlapping triangles, inverted normals, open edges or other geometry issues.
Anchor OutputParticles OutputParticles
Output Particles
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Phoenix particle systems contain Particle Channels for each particle, which represent the properties of the fluid simulation. Each Particle Channel has its own range of possible values that is most efficient for that specific channel type (see the Particle Channel Ranges). Here in the Output rollout, you can choose which Particle Channels will be exported to the cache files. |
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The particle export parameters share a User Interface to keep the user interface compact. Each particle system can be selected individually from the drop-down Output Particles list, and the output settings can be selected for that particle system. When a particle system is selected again, the same settings are retained. |
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