This page provides information on the Resimulation rollout for a FireSmokeSim object.
Resimulation uses an already simulated cache sequence with exported velocity (base simulation) to drive a new simulation with any of these added effects:
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You can resimulate over the resimulated caches and so on - it's not necessarily just 2 passes at most. |
Due to the difference between the compression algorithms used by Phoenix FD's Aura format and the OpenVDB format, the resimulation process may produce a different result when using exported VDB caches as opposed to Aura caches if the Storage Quality option in the Output roll-out is set to a value lower than 20 (i.e. Lossless). |
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UI Path: ||Select Fire Smoke Simulator | FireSmokeSim|| > Modify panel > Resimulation rollout |
Parameters
Enable | resim_resimulate_particles – Enable/disable the particle resimulation. Use this option to modify the look of Drag particles. The resimulation will produce the exact same result as the base simulation only with Steps per Frame = 1 in the Dynamics rollout. With a higher number of steps, the intermediate steps cannot be reconstructed, so full simulation is needed. |
Grid Resimulation
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Example: Resimulation with Wavelet Turbulence
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Phoenix has many tools for changing the animation timing of a cache sequence after it is simulated. Resimulation with enabled Time Bend Controls can produce smoother playback in cases where the Input Time Bend controls are insufficient. For more information on Resimulating with Time Bend, see the Tips and Tricks topic on How to slow down a simulation, animate the time scale, etc.
Use Time Bend Controls | resim_grid_timebend – Change the time scale of the base simulation according to the Time Bend Controls in the Input rollout. You need to re-scale the animation of all other interacting objects and sources in the scene as well. For constant play speed, use 3ds Max's Rescale Time feature. |
Time Bend Method | resim_grid_timebend_method – A method to use when scaling the time of the resimulation. Note that both methods work best when Steps per Frame on the Dynamics rollout is set to 1. Note that speeds below 0.2 may produce unsatisfactory results when using either method. |
General-Purpose – Works for all play speeds including backwards playback. It resimulates more quickly, but might produce flickering or jittering in the movement of the fluid. Sources, obstacles, or forces do not need to be present in the scene for this method. However, this method may not produce satisfactory results with animated sources. |
Slow Down – Works only for play speeds between 0 and 1. It will produce smooth playback without flicker or jitter but will add more dissipation in the long run, so it's better to combine it with Multi-Pass Advection. This method requires all used sources, obstacles and forces to be present in the scene. Any animation in the scene will need to be adjusted accordingly and slowed down to the play speed of the resimulation. |
Example: Time Bend Resimulation
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During resimulation, Phoenix reads cache files in the Input Simulation Path, performs resimulation operations, and then saves a new cache sequence in the Output Simulation path. For more information on how to set up resimulation paths, see the Tips and Tricks page. |
Wait if caches are missing | resim_cachewaiting – When enabled, waits if the base cache file is not yet available. This can be used if another instance of 3ds Max is simulating the base cache at the same time (on the same or other computer).
Base Cache Files Path | resim_inpath – Specifies the base simulation caches which will be used as base for resimulation. $(same_as_output) by default.
Output and Render Path | resim_outpath – Specifies the path for writing the output cache files from Fire/Smoke resimulation. See Output Path for more details on the $(...) macros you can use. $(scene_path) by default (will append "_resim" to the end of the file name).
Click the "..." button to open a menu with the following options:
Browse - Opens a dialog where you can select where the resimulation caches will be written to. The filename you type in must contain # signs so each resimulation frame will be written to a differently numbered file. Also, you can choose between two file formats - AUR and VDB cache files.
Delete Cache Files - Clears the resimulation files.
Reset to Default - Resets the resimulation path to default.
Help - Opens this Help page.
If the Output and Render Path coincides with the Base Cache Files Path, Phoenix FD will not prevent you from overwriting your existing cache files. It's valid to do so if you need a more complicated setup or when not enough disk space is available. |
The following error message may appear when you start a re-simulation: "Cannot start the Re-Simulation! Please make sure the simulation was run with the 'Velocity' channel checked under the 'Output' roll-out, and that the cache files in the Simulation Input path exist." The reason may be that either the files in the Input Simulation Path do not exist at all, or they do not have Grid Velocity Channel exported when you have simulated them beforehand. Of course, you may use more complicated setups where you resimulate over an already resimulated cache file, or you may Load an existing base cache file as the initial state of the re-simulation. These are all possible; you just need to have velocity in the base cache and an existing path to it. |