Forum: Poser - OFFICIAL


Subject: White Artifacts ~ Lighting

bluecurry opened this issue on Mar 25, 2013 · 17 posts


bluecurry posted Mon, 25 March 2013 at 1:27 AM

Hi,

I've been working on this image trying to get rid of these white dots in the shadows of the hands for a while now. I've tried upping my shadow bias, turning off displacement (even though her skin does not have displacement enabled), ect.. I haven't been able to get them to disappear.

I recreated this scene from something that I was playing with before and lost when Poser crashed and I didn't save. There were no white dots on the original, so I'm unsure of what I am doing wrong.

Interestingly enough, the white dots appear on the subsurface scattering as well. Not sure if that means anything.

My lights are two point lights on either side of her head and a Diffuse IBL light (the default one that loads with Andy in a new scene). IDL (Indirect Lighting) is off.

I was doing this image as a learning expirience, so maybe someone can help enlighten me as to what I am doing wrong?

(Oh, and ignore the background, it's broken and it's not permanent)


seachnasaigh posted Mon, 25 March 2013 at 2:02 AM

Is that background a mesh object?  If so, post a screenshot of its material nodes.  Is there a hair item on the doll?  Her head seems shadowed.

     What version of Poser are you using?

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5


ashley9803 posted Mon, 25 March 2013 at 3:21 AM

I really love that image you're making bluecurry!

There seems to be a background prop/plane that is reclecting light. Turn off specularity and/or reflection on it. Click to enlarge image.

Edit - I should read the full post oops. The spots on the skin someone else will have to help you with.


bluecurry posted Mon, 25 March 2013 at 3:23 AM

I don't know if the background is a mesh object or not. I do not know the definition of a "mesh object" although I'm assuming it is something that uses a mesh? It's this object by Alfaseed.

I am using Poser 2012. No, she is not wearing a hair item yet. The hair that I was using was tripling the render time so I wound up taking it out while I tried to work the issue out.


monkeycloud posted Mon, 25 March 2013 at 3:42 AM

Are the white dots on the hands not rough fresnel reflection?

If you're using EZSkin, try reducing the procedural bump perhaps? Or I think there is a "rough fresnel" setting... er, or something :-/ On the bus just now... cant double check, sorry...


monkeycloud posted Mon, 25 March 2013 at 3:46 AM

Or, find the noise node in the shader for the hands, and reduce the z value, perhaps?


seachnasaigh posted Mon, 25 March 2013 at 5:18 AM

The bright "artifact" off to the side of the fingers is specular highlighting on the background prop;  look at the little material preview at the bottom of the Poser surface root node in your material room screenshot, and you can see it.  Decrease the specular value if you want to tone it down.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5


bluecurry posted Mon, 25 March 2013 at 8:32 PM

Hi,

Thank you for all the comments on the prop, guys, but my issue is with the model. Here is my picture without the background. Do you see the white artifacts on the insides of the hands?

I've managed to fix the prop with your input, so thank you, but do you have any knowledge or wisdom on how to fix those white speckles? If you right click and choose "open in new tab" it becomes bigger and you can see them clearly. Thanks.


monkeycloud posted Tue, 26 March 2013 at 3:55 AM

Pretty sure thats the fresnel reflection and bump (based on a noise node), per my initial suggestion?


bluecurry posted Tue, 26 March 2013 at 5:15 AM

Ah, thanks. Forgive me, I'm a little foot-in-mouth, and I did not realize that you were talking about the model with your original post.

Alas, I don't really know my way around the material room. I looked for something called "noise" in the advanced tab, but did not see anything. Here is a pic:


monkeycloud posted Tue, 26 March 2013 at 5:39 AM

Okay - there's no noise node there.

Procedural bump in that shader is via the "Turbulence_2" node, from what I can tell.

As a test, try setting the "Bump" channel value (in the main PoserSurface node) to 0.

See if the white dots disappear...

If they do, you likely do want some bump still... just not as much... so try a value of 0.001 or even 0.0005 instead... etc.

Alternatively, reducing the z scale in "Turbulence_2" might help... I guess.

I don't know if the procedural specular (that other "Turbulence" node) could also be a potential culprit?


ima70 posted Tue, 26 March 2013 at 6:02 AM

Those artifacts are called fireflies, and I get them more visible with strong back light, in this render I use a very simple material on Miki 2, just a texture conected to diffuse color, no bump, no specular, no scatter.

millighost posted Tue, 26 March 2013 at 7:10 AM

Usually those artifacts are holes; in the illustration below i rendered a sphere with the polygon boundaries made visible and "smooth polygons" set to on in the render settings. The holes occurr when the mesh tears at the boundary of polygons and are visible as white dots (where the thing behind them shows through). Although those are bugs (errors) in Firefly (poser's render engine), and fireflies also are bugs in other render engines, those are not fireflies in the common sense (every firefly is a bug, but not every bug is a firefly).

monkeycloud posted Tue, 26 March 2013 at 7:53 AM

I'm just not convinced that what I'm looking at in the first render posted by the OP, on the hand, is actual artifacts as much as it is just unwanted reflections...

...which to a lesser extent... and indeed even to the extent I see it there, are not in fact that unrealistic??

If they're something equivalent to fireflies though, maybe they're bursts of excess translucency from the scatter or something?

Maybe I'm not seeing what's being referred to though...? I keep having to remove the tiny specs of white dust from my LCD to make out which are the actual white dots on the hands... LOL :)


bluecurry posted Tue, 26 March 2013 at 8:48 AM

At first I did not know if they were artifacts, either; I only decided that they were when I changed the lighting many times and they did not disappear.

I read something about what millighost said while researching before making this thread. At first I thought it was that, but when I tried the solutions provided in the threads, none of them worked.

Removing the bump got rid of most of them. There are still a few there. But what you said makes sense monkeycloud. Why would I want the same amount of bump up close that I would from far away? I should have turned it down anyways. Well, I never said that I was the smartest person alive.

I'll probably re-add some bump for the sake of consistency with the rest of the skin, but here was my result.

Thanks for all the help and patience, all.


monkeycloud posted Tue, 26 March 2013 at 9:06 AM

Yup - that's certainly removed the white bits I was seeing... which were mostly coming round the edges of the fingers.

For realism, you, of course don't probably want it too smooth... I'd reckon.

But it depends - the latest version with no bump now looks like the girl has a much better hand moisturising regime ;)

I wonder if the remaining white blips... which to be honest I'm struggling to make out... are derived from the Turbulence node on the Alt Specular channel... or if they are a scatter artifact... or just good old raytrace / mesh bug related fireflies?


SamTherapy posted Tue, 26 March 2013 at 10:08 AM

I have no working experience of the current versions of Poser but they all look like aliasing jaggies to me.

 BTW, in the material shot you provided, Reflect_Lite_Mult is checked.  It should be unchecked for absolutely everything, always.

Coppula eam se non posit acceptera jocularum.

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