Due to work constraints I've only been able to skim the forums and tutorials and stuff. One of the impressions I've picked up, probably wrongly, is that IBL is somehow majorly different to what has gone before. Perhaps I've gotten mixed up with discussions about scenes and surfaces lit by 'light probes' only, with no actual lights present. Anyway, when I rendered the image above I spotted something that was quite familiar.

The scene is lit by the 'office' IBL (with ambient occlusion) included in the P6 library. On the red surface an array of shadows from the skull is visible that looks very similar to the result you'd get from using a complex light sphere arrangement in Poser4. Yet, unlike when using those, the light controller in P6 when using IBL only shows a minimal light arrangement.

Does IBL work by setting up a sphere of lights in accordance to the pixel layout on the 2D light probe (image)? If so, it's fairly clever, saving the user from arranging all those lights. But it also means the user cannot control the number of lights, nor each light individually.

If my skull image were done in Bryce, I would be advised to add more lights to my light dome (sphere) due to the multiple shadows showing.

BTW, I also used the gather node option, so the skull is picking up the red from the table in quite a realistic manner.

It's going to be amazing seeing the images coming out of the advanced users once they're up to speed with P6.

Attached Link: Lights/Shadows/Bounce with GatherNode

"Does IBL work by setting up a sphere of lights in accordance to the pixel layout on the 2D light probe (image)? If so, it's fairly clever, saving the user from arranging all those lights. But it also means the user cannot control the number of lights, nor each light individually." Close. In Poser, it creates "virtual" lights at rendertime that work in much the same way, reducing the overhead. however, the purpose of it is to allow the duplication of a "real world" lighting set up for compositing. In short, it was created to allow Filmmakers to more seamless blend digital creation and real world by providing a method for duplicating the subtle lighting levels of the real world setting in the digital space. Side benefit is much more apparently realistic lighting without the need for massive, system killing lightsets. Rather cool, isn't it?

Am I correct in assuming then, that P6 can't use HDR images and that all this image based lighting stuff is done using standard 24 bit images?

Based on analysis of the source files included with the application, it does indeed use HDR.

isn't the red bounce because of the AO?

Hmm, not sure what you mean there. Are there any files with the .hdr extension? That would definitely indicate Radiance format, or HDR images.

HDR is one of several formats that are used in HDRI. The codings can be used with a lightprobe node directly. The default images supplied for IBL use (Which is the correct term for what Poser is using, a subset of HDRI) are in jpg format, and really are little more than combined photogrpahs of reflective spheres -- the core source used for HDRI, which the software may or may not be converting natively. The red bounce is due to gather.

Ah, OK.If they are in jpeg format, then they can't be high dynamic range images. I was just curious, as everyone's been going nuts about the image based lighting, as to whether hdri rendering was being utilised or not.

Message edited on: 04/27/2005 23:29

I tried to load several formats of high dynamic range images - Poser 6 doesnt load them - so its actually JBL but not with HDRI images - not so different from the old light arrays used in P5

The only claims I've seen that it is HDRI lighting have been from users who don't realize that it's actually IBL being used (which can be used in the most generic sense as an HDRi term, but isn't accurate). As far as using radiance and similar formats -- convert them into numerical array format and you can plug those directly into the Probelight node. And it is significantly different from the old light arrays -- they generally use excessively high shadow values (without real need) and use significantly more resources than IBL -- or even IBL plus AO -- uses. At the most simple, you only load one light. At the most complex, you can load a hundred lights, each with their own IBL structure, plus additioanl shader capabilities which expand the ultimate function of each light. Hands down, the IBL system, combined with the other features, beats the snot out of those darn light domes...

Plus, with the old light domes, you couldn't totally get rid of "shadow banding" (the appearance of many shadows fanning out from your figure on the ground like you pointed out earlier) unless you added TONS of lights (maybe 100 or so). With IBL/AO, you can get the shadows almost infinitely smooth by increasing sampling, and playing with settings, and it doesn't affect the overhead too dramatically.

In your skull example above, I see some shadow banding from the AO, but if you increase the samples, it will smooth that out for you. You may have to play around with the settings a bit. Also, with AO, you have the ability to tell the engine where you want the soft shadows. You don't have to have them all over the scene... you can specify that you just want them on the ground, for instance, by attaching an AO node to your ground plane in the material room, and disabling AO from the IBL light. This will give you AO only on the ground, which would have been impossible with a light array in earlier versions.

Message edited on: 04/28/2005 05:51