Fluids - Pyro

Deborah R. Fowler

Fluids - Pyro Tips

Posted: 2013
Updated: May 2 2020

Remember in simulations scale is important. (The defaults are in meters, kg, seconds - as seen in the Preferences/Hip File Options)

See also

TIPS:

Animate your source - add some variety to your simulation (can be as simple as adding a mountain node with a time value in the offset parameter). Just as you should do with a liquid fluid. The shelf tool does this with the add_noise node in the source. Below are visualizations of fuel and temperature.

Add or manipulate data as necessary - Scott Keating's Volcano tutorial (2012) has an excellent, widely applicable example of this where he modifies the wind velocity to influence the pyro smoke plume. Although this tutorial is for an older version of Houdini, the technique is still widely used - manipulating data fields.In his tutorial a field is created by creating a box the same size as the pyro container and adding a volume sop. This is used to add vel (wind). A volume vop is used to add noise/direction to represent wind to add to the simulation.

Two aspects to pyro are simulation (shape) and render (shader):

Light your effect - light can shape the look of your smoke/flames - pay attention to the lighting as well as the shader
Use Background color for CONTEXT - always keep in mind what background you will be compositing onto - things look denser/fuller on dark backgrounds
Voxel resolution - the lower the number, the more details - the longer the sim. The resolution is key to the look. (This number depends on the size of your simulation ie. values .04 to .07 can give good results, lower will be more detailed, however will increase sim time but may work just fine for smaller effects. If you can afford the sim times lower it, but be sure to check more than the first few frames.)

Pay attention to the render settings: (see Mantra Sampling parameters)
- Volume Quality
- Volume Step Rate - vm_volumesteprate was renamed in a late build of 16.0 and vm_volumequality was introduced in 16.5 according to the forum post here