Hi All,
I am wondering if someone can give some insight into how the UHD Cache functions... I have a scene that I need to render a handful of cameras. For this particular project, I need to pre-render a UHD Cache and use the stored cache for rendering. Do I need to render a unique cache for each camera, or does the cache contain the secondary light solver for the entire scene?
Hopefully, that makes sense.
Thanks,
CHG
By default it's cameraview and frame specific, recalculated each time. Since the core philosophy of Corona is to keep stuff simple, there are not many options to tailor such optimizations in detail, as opposed to V-Ray which for instance allows you to seed such a calculations along a camera's path and precompute a giant irradance cache and view it externally even.
Note, no matter what you do, the first bounce is always brute force anyway, a cached first bounce was voted out a feature quite a time back.
Corona does allow you to save out the UHD cache as a file and reuse it. For flythrough animations especially useful for instance.
(As described in Corona's helpdesk article about it )I presume that this goes for different camera positions as well. The calculation always happens from the view of the camera though. So reusing for other cameras would not be ideal. Where the file's records don't cover the view, brute force will be used instead. I do wonder, whether it makes sense to make a 360° Camera, calculate the UHD cache and since it's 360° reuse it for all the cameras with proper coverage.
You can check how much of the secondary solver is used from the cache in the VFB by reading the "Success rate %" value. If it's 0, then none of the cache is used and the secondary rays are brute forced. Last time I did precalculation, there was a hard limit of 100.000 UHD records. Just FYI.