ComparaSim
Visually Compare Simulation Settings
In addition to visually comparing settings, you'll also find useful pop-ups that provide definitions and info for a variety of parameters. That makes ComparaSim a great educational resource as well.
To get started, choose a topic on the right or keyword search a parameter that you're interested in exploring. All simulation settings are tested at the defaults unless specified otherwise.
Pyro
ComparaSim Smoke, Fire, and Explosions
Smoke Scenarios
Disturbance Magnitude
Disturbance Block Size
Disturbance Continuous
Sourcing Variation
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Density + Temperature fields @ the default values when using the "initialize smoke" preset
-
Disturbance block size = 0.075m
-
Threshold Field = Density
- Threshold Range = 10,000 - 0 to effectively apply disturbance evenly throughout the entire sim.
- Substeps = Range from 1 to 5 based on CFL
- CFL Condition = 8 (Advection over 0.1m triggers substeps)
- Advection Reflection Disabled
- Approximate voxel count = 5.6 million (per sim)
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Density + Temperature fields @ the default values when using the "initialize smoke" preset
-
Disturbance Magnitude = 10
-
Threshold Field = Density
-
Source does not feature noise breakup
-
Threshold Range = 10,000 - 0 to effectively apply disturbance evenly throughout the entire sim.
-
Substeps = Range from 1 to 5 based on CFL
-
CFL Condition = 8 (Advection over 0.1m triggers substeps)
-
Advection Reflection Disabled
-
Approximate voxel count = 5.6 million (per sim)
-
Dissipation = 0.025
-
Cooling Rate = 0.25
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Density + Temperature sourced fields @ the default values when using the "initialize smoke" preset
-
Dissipation = 0.025
-
Source volumes do not feature breakup
-
Threshold Field = Density
-
Threshold Range = 10,000 - 0 to effectively apply disturbance evenly throughout the entire sim.
-
Substeps = Range from 1 to 5 based on CFL
-
CFL Condition = 8 (Advection over 0.1m triggers substeps)
-
Advection Reflection Disabled
-
Cooling Rate = 0.25
-
Approximate voxel count = 5.6 million (per sim)
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
No breakup in the source
-
Simulation Type = Sparse
-
Max Substeps = 5
-
CFL Condition = 8
-
Advection-Reflection = Disabled
-
Dissipation = 0.025
-
Cooling Rate = 0.25
-
Turbulence Swirl Size = 0.1
-
Influence Threshold = -1
-
Turbulence = 3
The turbulence tests use the turbulence microsolver within dops rather than the turbulence settings found directly on the sop-level pyro solver. The reason for this is because it's easier to control the Threshold Field / Influence threshold by setting the "Influence Threshold" to -1. This allows turbulence to affect all areas equally. The seed for the turbulence is also changed for each simulation.
---------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
No breakup in the source
-
Simulation Type = Sparse
-
Max Substeps = 5
-
CFL Condition = 8
-
Advection-Reflection = Disabled
-
Dissipation = 0.025
-
Cooling Rate = 0.25
-
Turbulence Scale / Magnitude = 0.5
-
Influence Threshold = -1
-
Turbulence = 3
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
Source features medium breakup
-
Simulation Type = Sparse
-
Max Substeps = 5
-
CFL Condition = 8
-
Advection-Reflection = Disabled
-
Dissipation = 0.025
-
Cooling Rate = 0.25
-
Disturbance Magnitude = 10
-
Disturbance Block Size = 0.5
-
Disturbance Threshold Range = 10,000 - 0
-
Turbulence Scale / Magnitude = 0.1
-
Turbulence Swirl Size = 2.5
-
Influence Threshold = -1
-
Turbulence = 4
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.015m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
Source features medium breakup
-
Simulation Type = Dense (With OpenCL)
-
Max Substeps = 99,999 (Substeps strictly determined by CFL)
-
CFL Condition = 7
-
Advection-Reflection = Disabled
-
Cooling Rate = 0.25
The timescale parameter is tested with 99,999 substeps and a CFL condition of 7. By doing this, it allows the pyro solver to use as many substeps as necessary to solve an accurate result. This is especially important to do when increasing the timescale because otherwise you will get inaccurate values and volume loss. In addition, during testing, there were some issues when using the turbulence microsolver within dops. Higher substeps led to higher values in the turbulence. So, if you decide to increase the timescale of a simulation, it's important to also double check that all your other microsolvers remain unaffected. If you are encountering issues with timescale, another method is to cache out additional frames at a regular speed and then use a retime node to speed things up when reading the cache from disk.
------------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
Source features medium breakup
-
Simulation Type = Dense (With OpenCL on)
-
Advection-Reflection = Disabled
-
Dissipation = 0.025
-
Cooling Rate = 0.25
-
Disturbance Magnitude = 5
-
Disturbance Block Size = 0.5
-
Disturbance Threshold Range = 10,000 - 0
Substeps are very important to pyro simulations because they provide extra detail, prevent mushroom shapes on the leading edges of plumes, prevent data loss when moving at high speeds, and assist in collision detection. In practice, I often rely on the CFL condition and set the max substeps to a very high value (like 99,999). For more info on the CFL condition, visit the keyword links below. In situations that feature really heavy pyro simulations, however, it may be better to explicitly state how many substeps you're looking for. Note that going from 1 to 2 substeps makes a dramatic difference. The change after 2 substeps becomes less impactful. However, once you reach about 5, the smaller impacts add up to a significant change in shape / detail.
------------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Density + Temperature sourced fields at the default values when using the “initialize smoke” preset
-
Source features medium breakup
-
Simulation Type = Dense (With OpenCL on)
-
Advection-Reflection = Double-Project
-
Dissipation = 0.025
-
Cooling Rate = 0.25
-
Disturbance Magnitude = 5
-
Disturbance Block Size = 0.5
-
Disturbance Threshold Range = 10,000 - 0
This test explores the visual impacts of Advection-Reflection. This is a great way to introduce extra details in your pyro simulations. It can help break up mushroom shapes on the leading edges of plumes. It also works better when you add substeps. It can also help preserve circular shapes in the plume.
--------------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Max Substeps = 99,999
-
CFL Condition = 12
-
Source features moderate breakup
-
Density + Temperature fields @ default value when using the “initialize smoke” option
-
Cooling Rate = 0.25
-
Disturbance Scale / Magnitude = 5
-
Disturbance Base Block Size = 0.5m
-
Disturbance Threshold Range = 10,000 - 0
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Max Substeps = 99,999
-
CFL Condition = 12
-
Source features moderate breakup
-
Density + Temperature fields @ default value when using the “initialize smoke” option
-
Cooling Rate = 0.25
-
Dissipation = 0.025
-
Disturbance Scale / Magnitude = 5
-
Disturbance Base Block Size = 0.5m
-
Disturbance Threshold Range = 10,000 - 0
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Max Substeps = 99,999
-
CFL Condition = 12
-
Source features moderate breakup
-
Density is sourced at the default value when using the “initialize smoke” option
-
Temperature is scaled up to a value of 4 to emphasize the impact of temperature diffusion with the sourced operation set to “add”
-
Cooling Rate = 0.5
-
Dissipation = 0.025
-
Disturbance Scale / Magnitude = 5
-
Disturbance Base Block Size = 0.5m
-
Disturbance Threshold Range = 10,000 - 0
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Max Substeps = 99,999
-
CFL Condition = 12
-
Source features moderate breakup
-
Density is sourced at the default value when using the “initialize smoke” option
-
Temperature is scaled up to a value of 4 to emphasize the impact of temperature diffusion with the sourced operation set to “add”
-
Dissipation = 0.025
-
Disturbance Scale / Magnitude = 5
-
Disturbance Base Block Size = 0.5m
-
Disturbance Threshold Range = 10,000 - 0
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Sparse
-
Max Substeps = 5
-
CFL Condition = 0.25
-
Advection-Reflection = Disabled
-
Dissipation = 0.025
-
Cooling Rate = 0.25
The sourcing variation demonstrates the effect of sourcing breakup. It ranges from very small breakup to the left to heavy breakup on the right. Both density and temperature have their volumes broken up in the same manner.
--------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
-
Voxel Size = 0.0125m
-
Simulation Type = Dense (w. OpenCL)
-
Max Substeps = 99,999
-
CFL Condition = 12
-
Source features no sourcing breakup
-
Density and Temperature are sourced at the default values when using the “initialize smoke” option
-
Dissipation = 0.025
In this test, we explore the impact that sourcing has on a default smoke plume. These collisions are placed within the barrels at their openings. There are a few interesting things to note in these tests: For one, it's interesting to note that the first two collisions spread the narrow smoke source wider to encompass the tops of the barrels. As the smoke is advected, they also create interesting details right above the barrels. The second collision object features a more organic, spherical openings, and also slows down the smoke more than the checkered grates do. The last couple of collision objects are interesting because they break up the shape of the smoke plumes without affecting their width as much. If you compare the first barrel (with no collision) vs. the last barrel, you'll notice how much detail is being added into the leading edge of the plume. This greatly helps in breaking up mushroom shapes. Last but not least, when colliding against smaller objects, it's important to use more substeps in order to ensure collision detection. In these tests, the CFL condition is set to 6. This means that if a value travels more than 0.075m (6*0.0125), the solver will introduce more substeps. More substeps = more simulation time, however, in the case of using collisions to break up shapes, it tends to be well worth it for the quality that you get. For a more intense effect, you can also increase the collision velocity. This will push the smoke away from the collisions more aggressively to introduce more breakup of the shapes.
------------------
The smoke scenario places a higher emphasis on disturbance parameters. Just about every smoke simulation requires it in order to achieve a detailed look. There are exceptions to this, (if your simulation is heavy in viscosity, for example), but most smoke simulations place a greater emphasis on disturbance.
The goal for each simulation is to isolate the visual impact of each parameter. When setting up your own scene, the values may vary - especially if you're simulating at a smaller or larger scale.
Smoke is particularly good at illustrating the impact of substeps and advection reflection as well, so a greater emphasis has been made on testing those parameters. For more info, click the keyword links below:
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Disturbance
"The disturbance force introduces small amounts of change, mimicking the effects of localized environmental change. This localized change in momentum cancels itself out over time, preserving the simulation’s general motion and overall shape."
In practice, disturbance is great at capturing smaller details in a pyro sim. It's not as great at capturing larger movements and details. Artists will often use disturbance to break up mushroom shapes that occur along the leading edges of smoke simulations or to add tiny bits of detail in general.
Disturbance has two primary modes: Block-based and Continuous. Block based gives you better control over how large the detailed shapes are. The block size is represented in meters, and the larger the size, the larger size the randomized forces are on the pyro. Continuous will provide a fuzzier, smaller-detailed look, and it is often better to use when trying to soften the overall look of a pyro simulation. Continuous mode can be useful when representing avalanches or areas of mist along a waterfall.