hi all,

this weekend I performed some additional research on this Raytrace Bounces. Some results were unexpected (to me at least) so I'd like to share them right now. In Poser, there are differences for reflect, refract and IDL.

Reflect: in sync with my earlier assumptions, killing the light rays early will make artefacts which show the contents of the Background slot in the Reflect node. At its default black those spots are quite visible but when one makes it white and plugs in an image, the raytrace bounces slider works as a discrminator between raytraced and mapped reflections (the first ... bounces are raytraced and then the map kickes in). But reflection is efficiently done in Poser, so increasing the slider hardly causes much pain.

IDL: in sync with my earlier assumptions, killing the light rays early will reduce the brightness of the IDL portion in the scene lighting and eventually might leave dark spots in the corners, as trhe rays are just not granted the time to get in there. Increasing the slider will reduce those spots, will brighten up the scene but also wil distort any previous balance between direct and IDL light used, as only the latter is brightened up. So it's not just about artefacts here. Note that via de D3D Render window, raytrace and IDL bounces can be set separately. Increasing the slider does raise rendertime but - in my opinion and findings - not to alarming levels.

Refract: here all my previous assumptions went off. In most software, like the early Bryce image bove with the looking glasses, killing the light ray implies that no light is passing through the image any more, and we might run into the artefacts we see with reflections. Not in Poser.
In Poser, Transparency and Refraction are treated as separate features, and only the refraction, the bending of light when passing a surface, is the raytraced thing. The Transparency is always there and is not affected by the raytrace bounces setting, and when the light ray gets killed it still passes through all the surfaces, it just stops bending only.
As a result, any artefacts when looking through a stack of glass objects like the looking-glass image above, will be hardly visible for the less trained observer. In other words: there is not that much gain from increasing the slider.
But... the pain is incredible, and render times almost go up exponentially when slider values are increased. And no gain, so low values are advized. This also holds for the Fresnel node equivalent.

So, raising the bar is great for reflections, brings some good some bad for IDL, and is a sure rendertime killer without much benefits with Refract or Fresnel nodes around.

I'll post some testrenders below. This study will be part of my large Material Room investigation, published this month.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though