Week 6: Particle and Car Lighting

After presenting last weeks progress to the mentors, my main goals for this week were to add the particle lighting on the environment and the car headlights. I started by converting last weeks version of the particles for shot 3 into mesh lights, rather than using an aiStandardSurface with emissive. I also separated the effect of the particle's glow on the car from the beauty layer to give Bua more control in compositing. After Bua blocked out the trees in shot 3 and passed that to me, I also created layers for the particle light glow on the road and trees. For this first test of the environment lighting I spent some time adjusting how much of the forest was lit up by adjusting the mesh light intensity, to try and believably match the particles effect.

I also added the motionvector AOV to the beauty render to help Bua with the motion blur in compositing. I then did a quick test comp with the new render layers in Nuke before passing them to Bua. In this test we saw that although the lighting on the car and environment was better, we weren't happy with the look of the particles themselves. We decided from now on we would render the particles used in the shot in Houdini while continuing to use them as mesh lights for the lighting passes in Maya.

Render layers in order: Beauty, Car Reflect, Particles Front, Particles Back, Road Glow, Tree Glow

After this initial particle light test, I moved on to working on the headlights in shot 1. I separated the mesh where the lightbulb would be from the rest of the headlight, and first tested it with an emissive shader. However I quickly found a mesh light worked much better.

No headlights Emissive shader on lightbulb Lightbulb as a mesh light

I then added layers for the headlights on the road and trees (which Bua previously blocked out). By this point Joleen had the first version of particles for shot 1 done, so I added them to the scene as mesh lights like I tested for shot 3. I then added the environment lighting layers.

Render layers in order: Road Headlights, Trees Headlights, Particles Road Glow, Particles Trees Glow

After rendering shot 1 and receiving the shot 2 particles from Joleen I set up shot 2 with the same render layers (excluding the lit trees as there are none visible). I then rendered shot 2 and did a quick Nuke test.

Render layers in order: Beauty, Car Reflect, Headlights Road, Road Glow, Beauty and Car Reflect (Nuke merge)

While waiting for my renders, I started working on the side and back headlights of the car. I had done some quick tests early on, but since the render farm was busy and I was not happy with the look after quite some time, I prioritized the front headlights for this week's render.

The issue I was having was getting lighting effects to show up properly with the transmissive shaders. The first thing I tried was adding a light behind the transmissive shader I had for the light, but it didn't show through the shader properly. Instead it looked like the edges were glowing. I attempted to adjust the shader to fix this, but the issue continued. I then tried using a mesh light, adding an emissive shader to the existing mesh, and duplicating the light and adding an emissive shader behind the shader with transmission (the results of which are below). I was not happy with any of the results, or any of the other tests I had the time for. I will continue to troubleshoot and work out the best method for these lights for next week.

Mesh light Emissive shader Emissive shader behind shader with transmission