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What’s best to reduce lighting artifacts?
Posted: 29 November 2012 11:06 AM   [ Ignore ]   [ # 16 ]
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wancow - 29 November 2012 11:03 AM

While I’m at it, here’s another one I’m seeing, usually, if not always, around anything transparency mapped.  Same Settings as above.

This is a bug with Deep Shadow Mapping in renderman.  Often adjusting the camera angle will make it go away, but not always.  The only sure-fire way is to switch all lights to raytraced shadows.

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Posted: 29 November 2012 11:17 AM   [ Ignore ]   [ # 17 ]
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adamr001 - 29 November 2012 11:06 AM
wancow - 29 November 2012 11:03 AM

While I’m at it, here’s another one I’m seeing, usually, if not always, around anything transparency mapped.  Same Settings as above.

This is a bug with Deep Shadow Mapping in renderman.  Often adjusting the camera angle will make it go away, but not always.  The only sure-fire way is to switch all lights to raytraced shadows.

If you go through the 3Delight forum archives, you’ll find that issue and the solution (change camera angle/use raytraced) going back for a very long time.  It’s not so much a bug, because it’s actually doing what it’s supposed to be doing…it’s just the math involved is coming up with a result that doesn’t match ‘reality’.

If I remember, there was a solution talked about a long time ago, but implementing it made DSM all but unusable because of how much it slowed things down…

The version of 3Delight, in the latest beta, includes a huge number of improvements to the raytracing subsystem.  Supposedly, in some cases, with raytraced shadows, it’s now faster than DSM…I can’t get the beta to run on my system, so I can’t check it out.

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Posted: 29 November 2012 11:29 AM   [ Ignore ]   [ # 18 ]
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Right, mjc is correct, I was glossing that all into the term of “bug” because it seems to me to be a design flaw that could be easily handled with some bounding controls.  But hey, I’m not a pixar programmer. :D :D :D :D

(wish I was though, lol)

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Posted: 29 November 2012 11:32 AM   [ Ignore ]   [ # 19 ]
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mjc1016 - 29 November 2012 11:17 AM

If you go through the 3Delight forum archives, you’ll find that issue and the solution (change camera angle/use raytraced) going back for a very long time.  It’s not so much a bug, because it’s actually doing what it’s supposed to be doing…it’s just the math involved is coming up with a result that doesn’t match ‘reality’.

Applying a bit softness to the shadows often fixes this as well for me.

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Posted: 29 November 2012 11:57 AM   [ Ignore ]   [ # 20 ]
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wancow - 29 November 2012 10:37 AM

Guys, is the shading rate and shadow settings the solution to all render artifacts?  I’m getting some very different ones… This is one type.

This is one type of issue I’m seeing (not the only one), sort of shadow lines…

I have UE2, shading rate is 8, Shadow Samples is 16 (on the render settings, I couldn’t find Shadow Samples on the UE2 settings)

A Shading Rate of 8 no wonder you are getting the lines. 0.50 for medium qualtiy, 0.10 even better quailty. (lower is better for shaing rates).

The softer you have the shadows the more you increase the Shadow Samples and lower the Shading Rating value is always a good idea for final renders UE2 doesn’t have Shadows Samples only Occlusion Samples

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Posted: 29 November 2012 12:00 PM   [ Ignore ]   [ # 21 ]
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It’s a tricky balance if I want to have my cake and eat it, or so it seems. I’m playing around with settings at the moment, largely with mixed results. Objects I want lit indirectly are often coming out very dark, whilst if I raise the UE brightness it effectively blows out any surfaces which are in direct sunlight. I might just cheat and render out a separate shadow map by setting the floor as a temporary shadow catcher and hiding the remainder of the scene. An ugly ‘fix’ to be sure, but more guaranteed to get the results I’m after.

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Posted: 29 November 2012 12:55 PM   [ Ignore ]   [ # 22 ]
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Manually added the shadows in Photoshop. It’s not perfect, far from it, but it’s looking a lot better than it did. I used a shadow catcher and rendered the scene, then used Photoshop to manually pick off the shadows from the image and apply it over the existing render. A little low-opacity eraser here and there to soften the shadow edges in places.

Again, it’s still far from perfect and I plan to do a much higher resolution render at some point, but for those interested, the image is below.

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Posted: 29 November 2012 01:58 PM   [ Ignore ]   [ # 23 ]
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HeraldOfFire - 29 November 2012 12:00 PM

It’s a tricky balance if I want to have my cake and eat it, or so it seems. I’m playing around with settings at the moment, largely with mixed results. Objects I want lit indirectly are often coming out very dark, whilst if I raise the UE brightness it effectively blows out any surfaces which are in direct sunlight. I might just cheat and render out a separate shadow map by setting the floor as a temporary shadow catcher and hiding the remainder of the scene. An ugly ‘fix’ to be sure, but more guaranteed to get the results I’m after.

That’s where playing with, in addition to the settings you are adjusting, the Ambient setting for each surface comes into play.

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Posted: 29 November 2012 03:14 PM   [ Ignore ]   [ # 24 ]
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HeraldOfFire - 29 November 2012 12:00 PM

It’s a tricky balance if I want to have my cake and eat it, or so it seems. I’m playing around with settings at the moment, largely with mixed results. Objects I want lit indirectly are often coming out very dark, whilst if I raise the UE brightness it effectively blows out any surfaces which are in direct sunlight. I might just cheat and render out a separate shadow map by setting the floor as a temporary shadow catcher and hiding the remainder of the scene. An ugly ‘fix’ to be sure, but more guaranteed to get the results I’m after.


If you use UE2 for ambient light only (occl/soft shadows) you can then and a plain ole distant light to raytrace your shadows. I usually set UE2 to about 30-40% for ambient. You can also add some colour to UE2 to add special effects (very light yellow or orange for a sunset for instance)

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Posted: 02 December 2012 09:01 PM   [ Ignore ]   [ # 25 ]
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Szark - 29 November 2012 11:57 AM
wancow - 29 November 2012 10:37 AM

Guys, is the shading rate and shadow settings the solution to all render artifacts?  I’m getting some very different ones… This is one type.

This is one type of issue I’m seeing (not the only one), sort of shadow lines…

I have UE2, shading rate is 8, Shadow Samples is 16 (on the render settings, I couldn’t find Shadow Samples on the UE2 settings)

A Shading Rate of 8 no wonder you are getting the lines. 0.50 for medium qualtiy, 0.10 even better quailty. (lower is better for shaing rates).

The softer you have the shadows the more you increase the Shadow Samples and lower the Shading Rating value is always a good idea for final renders UE2 doesn’t have Shadows Samples only Occlusion Samples

Waitwaitwait - don’t get Wancow confused - setting shading rate for UE2 to 0.1 is a bit stretching it, to say the least. The general shading rate in the “Advanced” settings - maybe (0.4 - 0.5 is generally good enough unless you’re rendering postmarks). But UE’s own shading rate is good enough at 4.

What works better is to up the Occlusion Samples of the UE. 128 is the default highest IIRC, but if you edit the parameter not to obey limits, you can feed much more to the UE - some people use 512.

Also you could half the “max error” parameter.

And, unless you’re using UE to cast giant directional shadows or GI, turn down the “max trace distance” to something sensible. It’s in centimeters, an inch is 2.5 cm. So 15 cm is generally more than enough for AO and even IDL.

Shadow samples in the general render settings only affects DSMs. If you ARE using DSMs, up it all the way to 64. Or better yet, use shader mixer lights and control the map samples individually. A distant light over a giant piece of architecture may need 160 samples, while a spotlight doing a local “fill light” job can get away with 16.

BUT the thing is, these artifacts wancow posted don’t look like insufficient samples are involved.

One thing may be shadow bias too low - it creates self-shadowing, especially on low-poly models. UE generally handles even a “cornered sphere” well at the default bias; USLK does not, in my experience.

Still, these artifacts look closest to subsurface scattering artifacts. Check if SSS is enabled in the surface shader - since most settings are done only based on “what looks good” (Elite products included), they often fail in lighting environments that don’t match the one the texture artist used. The most scientifically sound way to implement SSS is to set SSS shading rate to 1 or 0.5 (2 also might work for larger images or closeups), and SSS scale to 0.1.
It won’t slow you down much (I’d wager you won’t notice anything on a modern computer), but the artifacts should go away.

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Posted: 02 December 2012 10:01 PM   [ Ignore ]   [ # 26 ]
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DSM??? USLK??? What are those acronyms?

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Posted: 02 December 2012 10:07 PM   [ Ignore ]   [ # 27 ]
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barbult - 02 December 2012 10:01 PM

DSM??? USLK??? What are those acronyms?

DSM = deep shadow maps. This one you’d better jot down, it’s commonly used.

USLK - UberSoft Lighting Kit, also by omnifreaker: http://www.daz3d.com/shop/ubersoft-lighting-kit - awesome in its own right, but not to be used with older figures like, say, V3RR (Victoria 3 Reduced Resolution) or H3 (Hiro3): for instance, their arms come out faceted.

Hopefully the abbreviations were the only confusing part of my post.

UPD: on re-reading. GI = global illumination. IDL = indirect lighting. Just in case.

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Posted: 02 December 2012 10:19 PM   [ Ignore ]   [ # 28 ]
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Thanks! DSM I would have eventually figured out, but USLK, never. I’m off to experiment with your SSS (Subsurface Scattering - I got that one!) recommendations.

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Posted: 02 December 2012 10:35 PM   [ Ignore ]   [ # 29 ]
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barbult - 02 December 2012 10:19 PM

Thanks! DSM I would have eventually figured out, but USLK, never. I’m off to experiment with your SSS (Subsurface Scattering - I got that one!) recommendations.

You’re welcome! What you may also need to adjust when using SSS is diffuse strength - in theory, you should do energy conservation for the shader and have at least diffuse strength and SSS strength together equal 100, but in practice I’ve found that too much depends on skin textures. Diffuse is generally around 70 when I use UberSurface. Though I prefer UberSurface 2 http://www.daz3d.com/shop/ubersurface2-layered-shader-for-daz-studio , or plugging the shader mixer SSS brick into my network - their SSS settings make more sense.

Here are a couple of settings for US2 I came to after all the research, trial and error we’ve carried out once in a cool thread on the old forum:

HOT WAX:
SSS “skin3” strength 80%, diffuse strength 20%, about 25% specular, no spec maps, bump 100%, min/max values 0.1
SSS scale 1

GOOD SKIN:
bump min/max 0.02, spec strength 15% with bump maps, diffuse strength 40%, SSS strength 60% “skin3”, 0.1 scale

This was for David3 hi-res maps, so spec/bump values obviously need adjusting in case of other textures. Add velvet and adjust fresnel to taste.

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