Quote from: Oshyan on August 11, 2013, 01:31:21 PM
It comes down to the render bucket size I believe - large displacement that crosses multiple render buckets is problematic. This is why the 3D preview doesn't have the same issues, but it also renders to far lower detail so doesn't need to use buckets. You could try increasing the size of the render buckets (and uncheck auto-reduction), but this will increase memory use I believe.
This is very interesting to me. So I tried some variations.
I usually use 64 size buckets. I do this because when rendering animation I don't like the idea of 15 cores sitting idle while the last tile renders. Of course I pay somewhat for this as there is more overhead to setup and tear down each tile render. Finding the right bucket size is also highly dependent on the view and so a low number is not always ideal. (For this image execution time varied from 4:50 to 6:20)
Below are several images showing:
- the base render with tile 256 - looks OK but parts are missing at tile boundaries.
- an image showing the missing parts for 64, 128, 256, 512 sized buckets.
- a casual overlay of some of those tile boundaries relating errors to boundary alignment.
From this I am able to determine that increasing the tile size is very beneficial to getting better coverage but does not solve the problem on its own. I suspect we need Displacement tolerance as well. I will continue to experiment with that and the larger tile sizes.
Quote from: Oshyan on August 11, 2013, 01:31:21 PM
The solution for now is to increase Displacement Tolerance.
- Oshyan
Alas going from 1 minute to render a frame (default Displacement Tolerance=1) to stopping it at 9 hours (Displacement Tolerance=5) - well its a solution but its not a useable one. I hope to find a lower number using this new information.
More data soon.
Oh yes - when unchecking auto-reduction - I noticed my render never actually finished when using 512 as bucket size on a 1920x1032 image. I had to recover image from cache directory. Could be a small bug here with process never ending but have not tried with animation - stills only.