Lately, while working on my Iceland scene, I have been plagued with problems with intermittent black areas in the shadowed regions lit by the enviro light. I am wondering if I might have too much in my scene for TG to handle. I have a number of high poly objects, two 4096x4096 vector displacements, several similarly sized masks and color maps, a complex rock bed, a waterfall made with a really dense cloud layer and a complex network of blue nodes that I use to shape the cloud into a parabolic, soft, long-exposure type waterfall.
For a while, my waterfall was intermittently disappearing or rendering black where it was in shadow. Sometimes, from test render (crop area on) to test render, with exactly the same settings, the problem would come and go. I rebooted. No help. Finally, I took my main nodes and made a clip file and created a new file and inserted them. Then I checked and made sure that all of my settings were perfectly identical between the two files. The problem disappeared! So I went on. That problem never returned.
Now, I am getting weird dark areas and little light areas that shouldn't be there under my water.
Bear in mind that my scene isn't finished. I hope the problems don't delay me and prevent me from finishing in time for the deadline! I have spent many hours fiddling, trying to fix some of these problems rather than working on the scene.
Here is a crop showing something that recently reared its ugly head:
[attachimg=1][attachimg=2]
The little dark areas shouldn't be there. I have a fake stones rock bed under the water. If I disable the lake to see if it is the rocks, the dark areas go away. Notice that the dark areas are obviously not something reflected from above the water. There is nothing above the water corresponding to it. And I don't know what the little white splotches are. Those aren't part of my waterfall and I haven't yet made the splashy stuff that should go at the bottom of the fall.
I have tried disabling the displacement on the water that makes the waves and the artefacts are still present.
Sometimes, while testing with crop renders, the whole area where the rocks are reflected in the water will be entirely black.
At one point, the whole area in shadow was rendering black, including the terrain, my objects, and so on. All looked fine in the 3D preview.
Note that I have "ray trace objects" turned off. That is because I am displacing the moss on the rocks. My rock outcrop is hand sculpted. The moss is an OBJ created using ZBrush's "extract" feature on masked areas of the rocks.
Here is another crop demonstrating a problem. I disabled and disconnected the waterfall. I turned "ray trace objects" on. This ruins my moss since it doesn't displace. Anyway, notice that there are no artefacts:
[attachimg=3]
So I turned "ray trace objects" back off and did a smaller crop near the bottom of the area in the previous image. The reason for the smaller crop is that with ray tracing of objects off, it becomes much, much slower, and I am impatient and in a hurry to finish before the deadline. Here's what I got:
[attachimg=4]
Notice how black the upper part is, which is totally unlike the previous render.
So, without changing any other settings at all, I turned "ray trace objects" back on and kept the same crop to see what would happen. Here's what I got:
[attachimg=5]
The only reason that the little black border around the last two is different is that I quickly cropped the output in PS, leaving some of the unrendered black area in.
Notice several differences between the last two. With "ray trace objects" turned off, everything is darker. And bear in mind that the green foreground part is just displaced terrain. It is not an object. And it has a constant color applied. But notice the dark splotches on it. And notice that even with "ray trace objects" turned back on, there is still a black area near the top that shouldn't be there and which wasn't there in the first render of these last three.
What is going on? Is there any hope that I can make this thing work before the deadline?
