That's shadow bias, all right, from a ray traced light. The refraction node is (i believe) multiplying the shadows, and therefore the shadow bias as well. You'll want to go either really high or really low (I forget which at the moment) to get rid of it.

I love the refraction effect anyway.

Oh, absolutely! Don't change that part! lol

well, give it a shot without raytracing -- use depthmapped shadow and see what you get. Also, check to see if smoothing is enabled for the lenses -- that might have an impact. (as in, disable it).

Message edited on: 07/24/2004 19:20

Also, you might try increasing the "quality" integer on the refraction node. I don't know what your settings are, but that could have an impact. Also, if your refraction background is black, try changing it to a lighter grey color and see if that helps. Those black spots look like render artifacts to me. Basically, from having a low quality setting. Black areas of refracted material can come from light rays being bounced around, and not "escaping" the material. Be warned, increasing the refraction quality will also increase render time.

That wasn't clear. You want the reflect and refract of RayT...just not it's harsh shadows. Make your shadows with another spot and disable cast shadows on the RayT.

"It's also present whether I render with shadows or not."

This leads me to believe it has something to do with the scenerio I mentioned in my post above, and not the shadows. However, I don't know that it could be refraction artifacting since Poser doesn't use photons or caustics, but i'm thinking it has something to do with the settings of your glass material. Perhaps a screen capture of the material node would help rule that out also.

Another possible solution to remedy this might be to increase the raytrace bounces in Firefly render settings to something above the normal recommended value, which I believe is 4 in production mode. It will impact rendertime, but you can try increasing that value to 6 or more and you should see an improvement as well. In other apps, black artifacting in refracted materials is the result of a lack of ray depth, which this might resolve.

Message edited on: 07/24/2004 21:35

I can't have easy problems, can I? ;)

We must have cross-posted. hehe. Try increasing the raytrace bounce value in Firefly to something more than what it is now.

Tried 16 and 32 bounces, with the same result. Setting a transparency decreased it somewhat, although they were still visible. Changing the background colors on the refract and reflect nodes doesn't seem to do anything.

Just finished conducting a series of tests on this, and Richardson has the right answer, actually (which, since he's had this same problem before, prolly works): You want the reflect and refract of RayT...just not it's harsh shadows. Make your shadows with another spot and disable cast shadows on the RayT.

"You want the reflect and refract of RayT...just not it's harsh shadows. Make your shadows with another spot and disable cast shadows on the RayT." Can you explain this more in-depth? He can't use shadows on the light he currently has them on, and needs to enable them on another light but turn cast shadows off in the render dialogue? I don't think I'm understanding it fully. Wouldn't turning off cast shadows disable all shadows in the render?

I'm still experimenting. You technically cannot turn off RayT as it kills the light. But you can reduce the map and shadow settings to where it has less than "global" settings. I posted a few photos not long ago. This is identical and so are the tests and suggestions. Someone Will solve this. Too good a thing to waste>

This is a "must-solve" problem in P5 I would imagine. If indeed it's the shadows causing that undesireable effect, then I have to wonder why he still got the effect when he rendered without the shadows.

Glass is often a difficult material to nail down perfectly, even in other apps, but I've only ever seen shadows produce that kind of effect from refraction in Poser. Usually it's a matter of ray depth, IOR value, or "exit color" that produces black artifacting in the material. But Firefly seems to handle all this a little different than I'm used to dealing with in other apps. There doesn't seem to be as much up-front control over refraction materials as I'm used to dealing with, but I'm sure somewhere in the various node connections or light settings there's a solution.

Message edited on: 07/24/2004 23:47

update -- I'm tracking down a similar issue in Pixels3D that had a solution, but it's proving bothersome to find. Since the underlying engine is much the same, they are an outstanding resource for tips and tricks. (Thanks to Stewer for pointing in that direction)

Bookmarking this as I've had the same issue LOADS of times and it's really getting on my nerves. Not only with glass, mind you, but often on the teeth as well. Seems like it happens on shiny things. On my picture "Bruce" I had to drop using ray traced shadows, as the glasses got speckled the exact same way as on FyreSpiryt's pic. But then I get the Glowing Nostril syndrome instead :o( And I really LIKE the super-crisp shadows produced by raytracing. I've tried numerous settings as well, so far with little luck, so, ynsaen, I HOPE you find a solution :o)

Refraction does some strange things when your surfaces get close together. If you add the nose piece to your glasses (strangely missing from most 3D wire frames) or pretend that there is one, and move the glass a little away from her face, this may clear up.

One thing you might try is looking at the glasses and checking the back side of the glass if there is one. Poser 5 dosn't like two sided objects. It may be getting fooled by the backside of the glass. You could try flipping the normals on the back side, or delete it. Using the grouping tool.

Try to make the background color of the REFLECTION node white. This color will be used when the bouncing rays don't meet any object in your scene. i.e. whenever they go into infinity. Willy

Well, out of curiosity, I scaled the glasses up. There were still speckles, although they were a lighter graey, and they moved from the edges to the center of the lens. shrugs The lenses are not a two-sided polygon; they're a solid shape. It looks like they're flat on one side and convex on the other. I also tried this on another pair of glasses in which the lenses were squashed cylinders. Changing the background colors of the reflection and refraction nocdes didn't have any effect; speckles were still there.

"The lenses are not a two-sided polygon" Yes but your trying to render through Two Transparent surfaces (Front and rear of lens), and I think that may be the problem. Try getting rid of the flat surface.

Open the lenses up in UVMapper Select the facets in the rear part of the lenses (this is not as easy as it sounds, lol) invert save render. Someone let me know what their results are, pretty please :)

That's just damn strange refraction behavior in my opinion. Most likely a bug in either the material or the renderer. It's refracting close-up object surfaces incorrectly.

Message edited on: 07/25/2004 21:11

yeah -- I was working with them without a face. Ok, that establishes that it is based in the shadows for certain, and not the geom. Three thoughts down, but now we know what to focus on. Still workin on it. :)

I have one more idea if you want to try it.

Use the grouping tool again, and select the lens. Then hit the "Create Perspective UVs button."

This will change the UV mapping on the lens so it directly faces the camera. So do this with your scene set up the way you want to render it.

Good luck with this. :)

Tried the perspective UVs thing, and there was no effect.

My money's on a bug. Probably won't see a fix till P6. Hope I'm wrong though. Ynsaen, please prove me wrong! ;-)