Shadows

Everything about development and the OpenMW source code.
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Greendogo
Posts: 1365
Joined: 26 Aug 2011, 02:04

Re: Shadows

Post by Greendogo » 19 May 2018, 16:10

I'll build it was well. I can't build installers, but does anyone want the Windows exe?

imec
Posts: 32
Joined: 13 May 2012, 22:03

Re: Shadows

Post by imec » 19 May 2018, 16:48

I think I found a problem. A high view distance with a high uniform log ratio seems to cause flickering. I set my view distance to 250000 because it's just enough to see all of Morrowind plus most of the completed sections of Tamriel Rebuilt. However, to get nice splits up close I had to raise my uniform log ratio to 0.985. For some reason this causes flickering on objects when viewed parallel or opposite to the light source.

I could just be misusing that setting though. Apologies in advance if that's the case.

Edit:
After testing more, it seems like the default uniform log ratio of 0.5 only works without distortion at a view distance of 6666. Once you start enabling distant terrain and pushing the fog back, higher values appear to work better. I have found that a value within the 0.9-1.0 range starts producing the best looking splits rather quickly. The vdlsm-meddling fork is really useful for figuring out where splits are (especially if your debug overlay doesn't work).

My uniform log ratios might be completely wrong and defeat the purpose of this implementation for all I know, but even then, the shadows in-game are simply beautiful. Yes, there are small issues with flashing foliage, empty spots at base of certain models and the occasional hole in terrain, but overall they look easily as good as some of the latest open world shadows if you can look past these very small issues.

Here are my settings if anyone is interested:
viewing distance = 21903
distant terrain = true
number of shadow maps = 3
allow shadow map overlap = true
split point uniform logarithmic ratio = 0.9
split point bias = 0
compute tight scene bounds = false
shadow map resolution = 4096
minimum lispm near far ratio = 0.25

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AnyOldName3
Posts: 879
Joined: 26 Nov 2015, 03:25

Re: Shadows

Post by AnyOldName3 » 20 May 2018, 00:01

Code: Select all

compute tight scene bounds = false
You'll almost certainly get much better results with this enabled. I'd potentially say it's often more effective than quadrupling your shadow map resolution in the situations where it helps, which isn't all situations.

As for the uniform/log ratio, all the papers I can find say it should be best at 0.5, but when 'allow shadow map overlap' is enabled, it looks better closer to or at 1.0. I'm surprised it's causing any issues, though, so I imagine that any additional flickering you're seeing was there all along, but you couldn't tell because it was being blurred out.
AnyOldName3, Master of Shadows

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