Pyro fire test

[Pancho]

 

O.k., finally managed to embed the video correctly.

 

For my first try, I'm quite please, but I do have a few questions regarding the workflow.

First of all the I wonder how to save memory. In order to keep the sim times moderate I upresed the sim. Since I cached the upres sim, my HDD space quickly disappeared. Wouldn't it be better to cach the low res sim and upres it on render time? I just wonder how to do this, since the shelf upres takes all the data from the low res DOP directly. How would one set this up, if only a cached sim would be available?

My sim isn't very large (300x600x300 approx.), but the result is still kind of low res. If I would need to have a really large fire (like a whole room or woods on fire), what's the way to sim and render it. I guess there'll be something like memory and speed issues both in the sim and render stage. Although a billowing smoke sim (burning oil well) would need an insanely high amount of divisions.

Any ideas?

Cheers
Tom

 

Edited May 4, 2018 by Pancho

[Polyxion]

Hi Tom,

first of all the detail really depends on the source itself and on the feature sizes of the forces you apply. So before upressing and simulating with a crazy amount of voxels it is really important to have an interesting and detailed source as a base. For example you can use the noise in the fluid source to mask out your source volume and get more broken up patches. In the simulation itself use microsolvers like turbulence and shredding to modify your sim and add detail. To safe disk space write out only the fields that you really need. For example storing velocity will take up three times as much as density because it has to store 3 floats per voxel compared to 1 float for density. 

I would also recommend to simulate dual rest fields and use them to add detail during render time in the shader. Make sure you turn them on on the smokeobject and the pyrosolver and set the right frame offset and blending depending on your scene. In the pyroshader you can then mask your fields with noises based on these advected positions. You can also use different noise sizes and patterns for different fields e.g. heat and temperature.

cheers

Edited May 6, 2018 by Polyxion
spelling

[Pancho]

Thanks so much for the tips and tricks!!!

[Pancho]

Finally some major difficulties. As soon as the flames start to rise there are strange squares on the sitting area of the chair.

I disabled all shape settings, changed substeps on the DOP network and the solver, changed the projection type, but couldn't get rid of it. Anybody an idea? Looks like an equalizer on an old stereo. Several squares on top of each other. It's rendered with Redshift. Might be something very common or something mysterious. No idea....

 

[Pancho]

One should be careful with the substep settings on the solver. Only difference here: Left side with 4 max. substeps, right side 1 max. substep.