rendering ter file with mountain - holes in terrain

Started by neon22, August 02, 2013, 05:33:59 AM

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Kadri

Not sure if that it is the same problem in the images in your last post.
It could be the water shader node(?) causing that problem.
I had mostly problems with it in the past.
If i remember right when i used only 1 CPU core i got rid of that black squares.

Neon try to render one problematic image without that shader (if you really use it of course ).




neon22

#16
Quote from: Kadri on August 12, 2013, 11:36:53 AM
Not sure if that it is the same problem in the images in your last post.
It could be the water shader node(?) causing that problem.
I had mostly problems with it in the past.
If i remember right when i used only 1 CPU core i got rid of that black squares.

Neon try to render one problematic image without that shader (if you really use it of course ).
Sure - here you can see a similiar result without the water.
visible at Q=0.3, bad at 0.4. Scene entirely black at 0.5
Of course this scene is extreme in the nature of its displacement so is very much a test case.
But it does show the relationship between quality and this error.

I also checked it with 1 core instead of 16. interestingly similar but unexpectedly different. weird.

Kadri


Thanks for testing Neon.
Interesting.

You could try some workarounds maybe...
Use a different Planet node with high displacement tolerance settings over the other one with masking for example to lower render times.
But i actually lower my displacement settings mostly and change the scene if possible, when i encounter such problems.

Just curious how a much bigger ( 4 times or more) render with low quality render settings and different bucket settings etc. might look , Neon?

neon22

Quote from: Kadri on August 12, 2013, 05:19:17 PM
Just curious how a much bigger ( 4 times or more) render with low quality render settings and different bucket settings etc. might look , Neon?
Hmm its weirdly frustrating. Here it is 4k wide but entire image renders black if Q gets over 0.1
But if I render it cropped, I can get Q=0.4
Highly non-linear... I guess I could tile it using tgd_Batch and render it large that way. Just as well I don't need to :-)


neon22

After much experimentation I have come to the following conclusions:

If you have missing geometry from extreme displacements in your scene you should try the following, in this order:

  • Increase the Max Bucket size in Render/Advanced/Bucket Controls. Default 256. Increase to 512 or higher.
  • Try switching off "Allow auto reduction" in same Render Bucket control.
  • Increase Displacement Tolerance in the Planet node. Default is 1. Try 2 or larger and reduce, until problem reappears.

  • values over 3 indicate you have more serious problems.
  • values over 4 will make your renders too slow to be useable. Find another solution.

In some special cases - you can get a good solution by just rendering a cropped region around the failure point, and by lowering Render Quality. But these last two will only help in weirdly catastrophic situations involving unusual node connections such as multiple compute terrains. Generally these last two will not help you but they do indicate where the problem lies.

Following steps 1-3 and trying them one at a time will result (if successful) in keeping your render times as low as possible.
You will need more memory as the Bucket size increases - so this may place a limitiation on you.
Increasing the Displacement Tolerance will directly affect render times by a large factor. Try it last.

It is noticeable that the effect is amplified if the displacement projects into the camera viewport. So looking down on a mountain might render well, but looking up at the mountain will exacerbate the error and parts of it might disappear...