Week 6: FX Refinement

This week I was focused on getting more iterations of the smoke/exhaust for shots 1 and 2, mainly getting critique from the mentors implemented in shot 1 and correctly setting up the render layers for shot 2 so the exhaust would show up better in post.

Here's a flipbook of the latest iteration inside Houdini. I think that the exhaust in the wheel well is a lot better than last week, however I think the behavior of the smoke still feels too wispy as it comes off the back of the car, so I need to experiment more in the coming week with noise in the disturbance/turbulence field (pulse and block size, amplitude, roughness, etc. in the pyro solver). This week I did add some fans on the back size of the car as well, as I saw that Deja has used that technique and gotten good results, so that might also help with the overall behavior.

Here are some videos I've been using as reference:

After troubleshooting with Eaza and Camilo we were able to get a render with the exhaust looking a little bit whiter/grey instead of the reddish-brown or black we were getting beforehand. Now that the render layers are properly set up, the FX can be color graded separately without affecting anything else in the scene. However, this color grade in particular reveals a lot of problems. With shot 010 the exhaust seems way too dense, and the attribute transfer radius on the ground is clearly visible here. There also is a mixing effect going on where the burnout trails look very smoke-like, while the burnout smoke around the tires still looks really dark, so this will need adjusting. Hopefully the solutions are as straightforward as tweaking the AiStandardVolume shader parameters. I also think there's some strange behavior right before the car takes off on the table; it feels like the smoke should almost wrap around the table instead of moving straight out. Right now, I am using a simple grid as the ground plane for the collisions, so I think this coming week I will also try to add some proxy geometry that aligns with the table in our scene and see if that affects the smoke's behavior at all.

Now that the exhaust is visible in shot 020, I would like to adjust the behavior. I'm in a limbo state with the effect right now of it either being too "poofy" in appearance or too erratic and choppy. Right now, I am using a particle system that emits particles from the exhaust pipes as the source for the pyro, so maybe the approach needs to change for this in order to achieve the look we want.