On 8/11/20 4:52 AM, Thomas de Groot wrote:
...
> 
> What puzzles me in the resulting image here is the visible boundary 
> between the first partial render and the first restart at about one 
> third down the image. You cannot miss it. I never experienced something 
> like that before. From a couple of experiments, I guess that it has to 
> do with the isosurface but I am at a loss about /why/. Any idea?
> 
> Using version 3.8 (also shows with 3.7 as far as I can tell), 6 threads, 
> on a i5 laptop.
> 

Interesting. Not sure.

While you were experimenting with continuations, did the discontinuity 
at the continuation move around substantially enough to be sure it's not 
related to camera rays and slope in some fashion? Guessing you are using 
a slope based pattern?

There are what I think of as 2.5 bugs in the shadow cache mechanism of 
v37 and v38 which are fixed in povr. And with povr, users can set the 
shadow tolerance which is in play with the bugs too. These bugs / 
limitations have the potential to behave differently depending upon the 
objects in play and so too isosurfaces over other objects. The shadow 
cache state wouldn't be carried through on a continuation so 'suppose' 
those 2.5 shadow cache bugs could be the cause.

There is too an isosurface/thread based cache mechanism specific to the 
isosurface, but looking at the code doubt it could cause the discontinuity.

I don't really have the machine for this scene..., but is the scene 
small enough you could package it up  - without the cloud media if 
possible? Maybe, if I render vertical slices or something I could 
reproduce it in v38, then try a similar continuation with povr without 
tying my machine up too long.

Bill P.

Post a reply to this message