Regarding the displacement changes: This is currently
work in progress and the wording in the release post wasn't very precise and I fixed it. Apologies for that.
Fundamentally, there are two ways how you can do displacement mapping: Either displace a subdivided version of the geometry during geometry compilation (which includes some trickery to make the subdivided geometry manageable) or do the displacement mapping on-the-fly during render time on non-subdivided triangles. Octane currently does the latter. This has the advantage that the memory consumption is smaller for detailed displacement maps. The disadvantages are that it's mathematically/numerically a lot more complicated and every triangle is handled independently of its surrounding triangles so getting the displaced surface water tight is fairly tricky.
We have identified at least a handful of issues in the current displacement implementation and are working on improving/fixing them right now so this work isn't finished yet by any means. Our near-term goal is to make the current system as good as possible. Of course, there is the possibility that we will not be able to bring it into a good enough shape and we will have to resort to the other approach (subdivide geometry) eventually. We will decide on that when we get to this point.
So what is meant with:
- Displacement of connected triangles are not torn apart anymore due to different vertex normals of shared vertices, e.g. displacing a cube doesn't create cracks anymore if the displacement map is continuous.
It's basically this problem: Imagine you've got a cube with this continuous texture, for visualization purposes I placed it into the diffuse channel:
To check if it's really continuous you can render the diffuse filter pass (there should be no visible edges between adjacent faces):
Now if you apply this texture as displacement map you get this in version 3.08:
while in version 3.07 you got this:
There was no way to get the displaced surface hole free without using shared vertex normals.
Again, there will be further improvements and we will see how far we can bring the current displacement implementation.
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
I'm sure they'll get it right soon though...
