How to setup animation flicker-free? [pre-1.0 HD cache]
This solution applies to Alpha 6, Alpha 7, 7.1 & 7.2 versions only. In Corona 1.0, HD cache was replaced by UHD cache which shouldn't produce flickering. To see a guide on setting up the new UHD Cache, please follow this link: How to use UHD Cache?
If you see "flickering" or "splotches" in your animation, this is most likely caused by HD cache GI solver. To make your animation flicker-free:
If your animation does not involve moving objects or changing topology, you can save your HD cache solution and re-use it for each frame. To do this:
1. Go to Render Setup > Corona Settings > Secondary GI: HD cache
2. Set "Precomputation" to "Calculate from scratch"
3. Set "After render" to "Save to file"
4. Optionally change File name
5. Start rendering and cancel it once the "Computing secondary GI" task ends
6. Set "Precomputation" to "Load from file"
7. Set "After render" to "Discard"
Note: this will only work for static scenes without any moving objects or changing topology (for example walk-throughs, fly-throughs, scenes where only camera moves).
If there are moving objects in your animation, make sure your HD cache settings are set to default or higher.
If you still see flickering at default settings, in Secondary GI: HD cache > Interpolation accuracy, change Direction and Position accuracy to a higher value (for example 80). Also change Record quality to a higher value (512 or higher).
If the problem persists after tweaking HD cache settings, you can set both primary and secondary solvers to Path Tracing.
Note: this will probably increase render times or introduce noise
Another possible solution, especially when both solvers are set to Path Tracing is to lower the Max sample intensity value in Render Setup > Corona Settings > Main settings > Speed/Accuracy balance to 10 or less. This will introduce some bias but might lower noise level.
See: Max sample intensity