Fire Tornado in Houdini
My recent experience working with GridMarkets on the fire tornado project was both efficient and highly educational. Although it required several custom solutions to achieve the desired level of control, it was a valuable learning process.
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by Sam Savage - October 2024
Breakdown
For Better Art Directability I set out a plan to build custom tools that gave me more granular control over the simulations. The Backbone of the majority of the setups was this “tornado force” tool for the pop simulation, where it can conform to any shape.
It works primarily off of grabbing attributes from the mesh or curve with a pc filter function and then using those attributes to create the necessary vectors within the sim such as the suction and orbit vector.​
I used a custom field based off of a height mask for the orbit, shredding and confinement in the pyro sim, which was essential for adjusting the behavior and characteristics of the fire simulation as to add break ups so it wasnt so uniform across the entire length of the tornado as well as try to make the vortex motion tighter as it continues to go higher .
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Custom tornado force
Im grabbing the up vector from my mesh [0,1,0] and the position, i'm using that to create my suction and orbit vectors.
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The distance calculation is based off the center/origin which is acting as a multiplier to the existing vectors.
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Since this works based off a mesh too, in sops u can make the tube wider or
smaller and it will match the shape in the sim
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Fire and smoke sims
The fire and smoke was simulated separately, however the fire’s vel field was used to influence the smoke sims velocity.
The smoke simulation used a custom vel field, which pretty much uses the same logic as seen in the pop sim, however it covers the entire bounds of the smoke simulation to ensure the smoke is always contained in the vel field and doesn't
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The Firenado separated
The smoke parts of the tornado separated
The emission pass
CustomField Ymask visual example
Gradient shows visual representation of strength of force scaled to shredding, orbit, and confinement.
Benefits of using GridMarkets
Over the course of the project, I had done a total of seven different simulations. Each one needed careful tweaking to ensure they all worked together as one piece, especially given the enormous voxel count involved—over 100 million voxels in the fire simulations alone. Main Fire sims took 9hrs on the farm. On my machine it would have taken 13hrs.
Managing such a complex simulation would have been a huge challenge locally, both in terms of time and resources, due to the amount of elements I was dealing with. ​
However, using GridMarkets' render farm provided a significant advantage. By offloading the heavy computational work to the farm, the render times were drastically reduced, which made it possible to iterate much faster than if I were rendering everything locally.
The project was rendered using Karma, which was very easy to set up and get working with GridMarkets, in total it only took a couple days where as if i was to do it on my machine locally it would have probably taken upwards of a week +.
One of the most notable benefits of using GridMarkets' render farm was the ability to free up local resources while the simulations or renders were running. This allowed me to multitask and continue working on other parts of the project while the farm handled the intensive simulation calculations in the background.
Without the burden on my local machine, I could focus on refining the setup, testing different approaches, and preparing the next stages of the workflow.
This parallel workflow wouldn’t have been possible without the flexibility offered by the cloud-based farm, which ultimately saved me a considerable amount of time and improved the overall efficiency of the project.
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Sam is excited to take on new projects to further develop his skills and is always further improving his knowledge through personal work. Sam is currently available for freelance / studio job opportunity's, you can find his socials:
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linkedin.com/in/sam-savage-98a75721a
https://www.instagram.com/savage____fx/
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By: GridMarkets marketing
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