Forum: Bryce


Subject: Ray Depth Results

shadowdragonlord opened this issue on Oct 01, 2003 ยท 15 posts


shadowdragonlord posted Wed, 01 October 2003 at 9:33 PM

Here's a stupid Rhino vase a made a while back for my chimney scene. One thing I had a problem with was null-shadows, the black areas that Bryce's raytracer produces when it "runs out". This is Take One, unsmoothed and rendered at RD of 4. I didn't let it finish AA (almost at the bottom), because it was garbage.

shadowdragonlord posted Wed, 01 October 2003 at 9:36 PM

And here's the next one, smoothed 180 degrees and rendered with softshadows and a RD of 6. (TIR depth is equal to the Ray Depth in all of these renders...)

shadowdragonlord posted Wed, 01 October 2003 at 9:40 PM

Another RD 6 image, this time with a small light rig to cut down on the render time. Notice the black null shadows at the top of the scene. There is no haze or atmosphere on these images, so far. Which was a problem, what if these null-reflections (sorry, I think I accidentally called them null-shadows earlier) were actually reflections ofthe black, nonexistent horizon? I like the lighting a bit better with the light rig, as opposed to Brycean soft shadows. (The softshadow render previously shown was at 64RPP, it took some time.)

shadowdragonlord posted Wed, 01 October 2003 at 9:45 PM

And this one, I did last night, same scene. I turned the atmosphere on, set it to some reds and oranges (custom mode, of course), set some light orange haze and fog, and rendered it at a Ray Depth of 18. TIR was also 18. There are no null-reflections, as the shadow color is the same. The render time was just over 2 hours, on my little Duron 1.3 with 512 MB-DDR. All of these are pure renders, no post... I finally got rid of those little bastard null-reflections! Thanks for viewing...

Slakker posted Wed, 01 October 2003 at 9:55 PM

Good study! I can't get over how real these look...


woodhurst posted Wed, 01 October 2003 at 10:27 PM

thats freakin amazing---these turned out awesome.


Quest posted Thu, 02 October 2003 at 12:01 AM

Which brings up an interesting question. What if you placed a white image on a large 2D face and placed it just behind the camera out of view so that it reflects off the glass vase, would that get rid of the null reflections? How about a white dome over the scene? Great demo and very nice renders!


danamo posted Thu, 02 October 2003 at 12:55 AM

Very thought-provoking experiment and renders. I really like that last render you did with a "roll-your-own" sky. I think it's very realistic. Excellent work your Lordship!


TheBryster posted Thu, 02 October 2003 at 7:05 AM

#4 does it for me! Execellent render....!

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catlin_mc posted Thu, 02 October 2003 at 7:46 AM

The final image really is the best. It looks most realistic in color and reflection. 8) Catlin


shadowdragonlord posted Thu, 02 October 2003 at 2:47 PM

Aye, thanks for viewing! Quest, null-reflections come from rendering with a Ray Depth that is too low for the object being rendered. Of course, Ray Depth has no effect on materials/objects that are not transparent or reflective. If you had a white background/sky shpere, you would still see black nulls. I believe the null-colors are based off of the Master shadow color, in the Sky pallete. One more render should clear all of that up, back in a few...


shadowdragonlord posted Fri, 03 October 2003 at 3:44 AM

Okay, I made a mistake, but it had nothing to do with null-refractions or whatever. I had my lighting setup backwards, meaning that all these image WERE rendered with softshadows in Premium mode, EXCEPT the first one. Other than that, this image will answer Quest's Question! Ray Depth of 2, TIR also 2. I also turned the Master Shadow Color to an purple, in case that had anything to do with the color of the empty reflections. It did not. Empty reflections, like quantum singularities, are black, regardless. Now I wonder if empty reflections have any ambience in True Ambience modes...

catlin_mc posted Fri, 03 October 2003 at 5:40 AM

I like this one too. It looks like a beautiful smoked glass, which means that null reflections are not all bad. 8) Catlin


Ang25 posted Fri, 03 October 2003 at 6:05 AM

So would a thinner vase need less TIR/Ray depth? Or does the thickness make no difference in which case we could just say "if you want nice glass use TIR set at 18". BTW #4 is beautiful.


shadowdragonlord posted Fri, 03 October 2003 at 7:23 AM

Ang, there really is no way to judge such a thing. Bryce's render report wouldn't, for example, say how many bounces a particular object in the scene used... Or an average, or anything like that. But consider that this glass object is an actual Rhino object I modeled. It has an inside and an outside face. So, if you shot a ray straight at it from a perpendicular angle, it would need 1, 2 (for the first side) then 3 and 4 counts to emerge from the other side. And every angle of incidence that is NOT 90 degrees dead on, would need progressively more Depth to let the ray emerge. For example, a light ray going almost straight down along an edge? The more Ray Depth, the merrier! Considering that this model is fairly high-polygon, and smooth, I'm thinking that 18 is probably as high as necessary, although mathematically 16 would make more sense...