This lesson gives a sample lesson plan for introducing a workflow that optimizes the GI calculations when rendering a fly-through animation.
- You can start with the challenges that rendering animations with global illumination present
- The position of GI samples varies slightly from frame to frame which causes flat diffuse surfaces to flicker.
- You may show some animations where this is visible
- A high-quality GI is needed to reduce the flickering.
- Settings that usually create great quality still images often produce flickering in animations because the movement makes the tiny imperfections more noticeable
- These issues boil down to the fact that rendering flicker free animations requires a lot of render time
- Next you can point out the solution that V-Ray offers - Using Irradiance Map as a primary bounce engine allows us to create one single high quality GI solution for the entire animation path as long as only the camera is moving.
- The Irradiance Map only calculates the GI for the parts of the scene visible from the camera. This means that we need to render the animation in two phases:
- We generate the Irradiance Map for the entire animation path
- Using the previously calculated Irradiance Map we render the entire animation
- You can explain how the Irradiance Map works when combined with Brute Force and Light Cache as secondary bounce engines
- It doesn’t matter whether we are using Brute Force or Light Cache, all the GI information gathered by the Secondary Bounce engine is saved into the Irradiance map
- Saving the Irradiance Map into a file and then loading it means we can disable the Secondary Bounce engine.
- To optimize the first phase of the workflow we can:
- Enable the Don’t render final image – we only need the GI calculations performed so we can save time by not rendering the image
- Render every Nth frame – this value depends on the distance the camera travels from frame to frame. We should set it such that we have only a small overlap of the surfaces visible from the camera when moving from frame to frame during the GI calculation
- In the end, we can use the Irradiance Map Viewer to make sure we have a map that completely covers the animation path
- When rendering the final production quality animation, it’s important to:
- Remember to disable the Don’t render final image checkbox
- Render every frame
- Adjust the AA Quality to fix any anti-aliasing issues
- In this cycle, you can demonstrate the workflow for optimizing the global illumination when rendering fly-through animations with V-Ray
- You can either use the scene and handout we provide or create and use your own materials
In this cycle, you are going to let your students experiment with the provided scene. You may want to give them the provided handout to use as a guideline