Holes in the terrain?

Started by domdib, April 03, 2009, 05:04:53 pm

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domdib

Can anyone suggest what is causing the strange white artifacts in the shadow of the landscape reflected in the lake? I thought that this was the known issue that required ray traced shadows to be enabled and turned on, but having done this, the artifacts are still there. And it can't be waves on the lake - as you can see from the cloud reflection, the water surface is completely flat. Quality is 0.8 AA 5.

Tangled-Universe


domdib


neuspadrin

I've noticed this with an occasional scene of mine, where it seems certain displacements let some light through for some reason where it just pops through with single dots of light oddly placed in middle of full shadows.  I have just be photoshopping out as i've never had too many.

Tangled-Universe

Thanks for posting.
I checked it with cropped renders with GI @ 1/1 and it was still present so that speeded up testing tremendously.

I think I have tried everything I can think of so far, but was unable to solve it.
My guess is that this is a bug. Actually, I have the same problem in my Jungle image as well, but it isn't as clearly visible as here.

I tried settings threads to 0, minimum cache size, large cache size, micro-vertex/detail jitter switching,  increased atmo/cloudsamples, different GI, different resolutions and AA and I also connected the compute terrain which you actually forgot or was part of your problem-solving process. I probably tried more stuff, but I can't even remember anymore :)
Maybe Matt can chime in here for more suggestions.

Martin

neuspadrin

Quote from: Tangled-Universe on April 03, 2009, 06:37:47 pm
I tried settings threads to 0, minimum cache size, large cache size, micro-vertex/detail jitter switching,  increased atmo/cloudsamples, different GI, different resolutions and AA and I also connected the compute terrain which you actually forgot or was part of your problem-solving process. I probably tried more stuff, but I can't even remember anymore :)
Maybe Matt can chime in here for more suggestions.


basically everything i did too, started at nodes and put in compute terrain, then slowly tried all sorts of various render options etc.

Mohawk20

Have you guys tried what happens if you bring the camera up close to the water, to see if it still happens?
Or just change the POV a little bit?

And increasing the render detail?
Howgh!

domdib

Now here's something even weirder. When I do crop versions of portions of the lake, the shadow of the landscape seems to fragment (see weird 3 crop1 below). And when I crop only on the portion that is reflecting the sky, new dark artifacts appear, from who knows where! (weird 3 crop2). Increasing the detail to 2 reduces their presence a little (weird 3 crop 2 detail 2). I hope this helps in the diagnostics.

domdib

Mohawk, following your suggestion, shifted POV much closer. Unfortunately, as you can see, same result. I even tried reducing the intensity of the sun, but that had no significant effect.

Clearly, something is messing up the shadow. It may have something to do with the fact that the terrain is procedural, with three different power fractals shifting things in three different directions (I got the .tgc from this thread: http://forums.planetside.co.uk/index.php?topic=5927.0)

Mohawk20

Ah, I could be a clipping issue. Parts of the terrain that are not rendered directly (because they're behind another part of the terrain), but should be visible in the reflection, but aren't/
Howgh!

domdib

April 04, 2009, 10:32:42 am #10 Last Edit: April 04, 2009, 10:49:50 am by domdib
Just to double-check it wasn't a water shader issue, I replaced it with a reflective plane. Sure enough, same problem. See below.

@Mohawk - so if it's a clipping issue, what's the solution?? The "Soft clip effect" in the renderer isn't connected, is it?

Mohawk20

I don't know...

Your last render looks even weirder. The water plane isn't rendered completely, and the reflections a double. It is a problem in the reflection shader, or the reflection part of the water. But I don't know how to fix it.
Howgh!

domdib

April 04, 2009, 02:30:56 pm #12 Last Edit: April 04, 2009, 02:33:02 pm by domdib
Mohawk, I didn't explain enough - that's not water at all. The lake object was replaced by a plane, which I made reflective using a reflective shader. The doubling of reflection is probably because the settings were a bit extreme.

I'm guessing this little bug isn't going to be resolved now until after Planetside have made the official launch - then Matt and the others might have time for bug squashing.

Oshyan

We'll definitely look at this issue, but yes it may be a few days while we finalize other things. It would be helpful for now if you could remove all but the base terrain shape and see if it still occurs. My guess is it has to do with 2nd or 3rd order, and/or extreme/unusual displacements.

- Oshyan

domdib

Oshyan, I'm sorry to report that this bug is a bit more extensive than I first thought, is TG 2.0 specific, and is not connected with the specific terrain file. Having tried unplugging various aspects of the previous terrain, to no avail, I decided to create a test file from the default scene. All I did was generate the heightfield, stick a lake in, and move the camera to a suitable POV. I placed the sun behind the terrain first, and sure enough, the bright spots appear in the shadow (see basic-(test-lake).jpg) - N.B., this is with ray traced shadows enabled. Then I raised the sun just above the horizon, and there are still white spots in the terrain shadow.

The reason I can say this is TG2.0 specific is I ran this test file through the Beta (excellent decision not to overwrite this with the final release, by the way), and no spots were visible in either case (see attachments). The test file is also attached.

I should add that this problem wouldn't have been detected if I hadn't decided to make the lake completely smooth, as obviously any waves would completely mask these minor artifacts. I guess that makes it a minor bug, as most people won't be using completely smooth lakes. Is it possible this bug is connected with the new settings for the "Ray detail region"??? I wouldn't know enough to fiddle with these settings to see if they might resolve it.