Addressed this week:
- Flame look dev – Refining the look of the flame in Houdini, added a secondary pyro simulation to introduce flame licks
- Flame motion – Refining flame speed and turbulence
- Integration of FX – Ensuring pipeline is working correctly and all FX integrate correctly
- Skid smoke – Adjusting color, diffusion, and adding atmospheric wind
Flame
The flame effects have been broken up into various render layers, including the main effects, a window reflection pass, a ground light pass, and a reflection pass on the bike. Here is a quick comp of all layers in the most recent version of the flame effects:
Here is the most recent composite produced by Michelle Rojas:
Utilizing the pyro shaders in Houdini, the flame is getting much closer to desired final look. IN addition to the pyro shader look development, a secondary pyro simulation has been layered on top of the other to get some licks of flame seen in some of the reference materials. This breaks up the solid look of the rocket flame and adds secondary motion to the flame.
The secondary flame is driven from the same source as the primary flame, however, attribute noise nodes are used to create masks on the fuel input. The first attribute noise creates small isolated points with the fuel values at 1, while the second attribute noise creates an animated mask to turn on and off the smaller values. These values are multiplied together to get the final sourcing for the fuel field.
A Houdini rendering pipeline has been created to smooth out issues with moving the effects to Maya for rendering and look development. This move has been successful, though the process of bringing in Maya assets required a fair bit of troubleshooting to ensure the effects and live action plates were in agreement.
A specific issue this last week was updating to the new camera and animation files. While importing the motorcycle alembics is straight forward, we had issues with render cameras not matching between versions. Working with compositor Michelle Rojas, it was discovered that forgetting to rebuild the hierarchy of the alembic archive when updating the camera Alembic file results in the old camera still being used for rendering. Though a simple mistake, this has massive impact on compositing the effects.
Several render nodes are used to generate all the layers needed for the compositing phase of the project. For the flame effects file, a zigzag layout is used on the nodes as there was a minor issue where the node appeared as if it was connected in the stack but in reality the input was disconnected but sat in such a way it was not easily spotted. By offsetting the node layout, this issue is avoided.
Smoke
Updates to the skid smoke this week was primarily centered and adjusting the movement of the smoke and refining the smoke’s look. A wind field was added to the smoke to create a little bit of drift to the smoke, and the turbulence and disruption fields were tweaked as well to get a softer, more diffused look to the smoke. Below is the effect in context: