Hi, I'm trying to figure out this new IBL thingie but just can't seem to work it out. I'd be really grateful if anyone could point me at a tutorial or two, as the one in the manual just skims over the subject. I've tried in vain to get anything vaguely realistic using the IBL/Ambient Occlusion/Raytrace combo, and I'm wondering if I've just totally misunderstood the whole concept. For example, am I wrong in thinking that I can use the same photo as my IBL source and also as the background of the render, to get the basis of a light-set that will nicely match the backdrop? I'm presuming I still have to use fill lights, etc. Anyway, any hints will be gratefully received. (Sorry if this has already been covered - the site search engine doesn't seem to be working today)

There's a script due out soon by face_off and maxxxmodelz that takes the guesswork out of IBL. I'll let one of them explain how it works....being in the dark, myself.

Attached Link: http://www.renderosity.com/messages.ez?Form.ShowMessage=2197864

Thanks for the consideration, richardson, but if it's the script I'm thinking of, I didn't have a hand in it's creation other than running some test renders with it for Paul (face_off). The idea and creation is all his alone. :-)

I'll let him explain it if he wants... since I don't know if he's going to actually release it anytime soon.

"am I wrong in thinking that I can use the same photo as my IBL source and also as the background of the render, to get the basis of a light-set that will nicely match the backdrop?"

The general "trick" to successful IBL/background compositing in P6 is to create a lightprobe image that matches your background image. These two images are not actually the same. Put simply, the image you plug into your diffuse IBL light in the scene should match the default lightprobe layout in order to work correctly. What I mean by that is, the diffuse IBL light reads specific areas of a lightprobe (spherical) image, and casts light on the scene according to that specific layout (ie., front, back, sides, top, and bottom). In order for your IBL light to match your background image, the image needs to be mapped correctly to the lightprobe coordinates (or at least reasonably so). You can then use some standard lights to "fill in" details like shadows, specular highlights, etc.

Remember that IBL itself does not affect specular properties (at least not without some advanced tweaking of material math nodes).

See the attached link to find out how lightprobes in P6 are laid out. Nerd provides a great zone map of P6 diffuse IBL lightprobes, and how each area of the probe affects the scene lighting. Olivier over at RDNA created one too, I believe, based on the same layout.

Message edited on: 06/14/2005 09:23

Here's a few more links to threads on RDNA which show various details about how IBL works in Poser 6... Creating Pseudo-IBL's In Photoshop A Tip About IBL Converting HDRI Images For Use In Poser 6 IBL lighting study

Great links! Thanks Maxxx!

::P6:: create your own Specular Light for ALL your surface with IBL AO

::P6:: Poser6 Mugger ;) and the HDR IBL Angular Maps

and using your own background and create from that IBL light is not real but can be done. Cath

Thanks for all this, guys. I can see I'm going to have a busy night!! Morph

Attached Link: http://www.users.on.net/~pkinnane/P6RealismKitNews.html

Morphy.... It all depends how realistic you want to get.... In general, a scene lit entirely from an IBL image will lack realism due to the lack of specular lighting and the "heaviness" of IBL AO shadows. I've found the best method to get around this is to use infinite lights for the majority of the scene lighting, and use IBL as a filler light. You can generate the infinite lights from an IBL image, although it's not for the faint hearted - see the tutorial in the link above. Alternatively, you can "guess" the light positions and strengths (which I've done on a heap of my renders and is suprisingly good!). The method described in the link above has been superceded by something I think works a lot better (which is what Richardson was referring to), and involves a neat trick in the material room on the ibl light to "carve off" the bright lights, and replace them with infinites. Again, it's not for the faint-hearted. I've been waiting for "stewer approval" (which has now been given) to make available a modified version of his poor-mans's IBL script before releasing the tutorial. IBL Image source and background image....If you are illuminating the scene purely from an IBL light + image, to get a matching background rotate your scene and camera 180 degrees in the Y Axis and use the middle of the IBL image as the background image. That way the scene lighting will match the background image. To "uncurve" the background image, feed the IBL image source into HDRShop (a free PC app), and do a [Image][Panorama][Panoramic Transformations]..convert from LightBall to Angular Map.

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Attached Link: http://www.users.on.net/~pkinnane/IBL%20Tutorial/SpecularIBLTutorial.html

New tutorial posted....

Thanks again to everyone who posted the great links in this thread. As you'll see, I still have quite a way to go in mastering IBLs, but at least I no longer feel *quite* so clueless, and my renders no longer look as if Jessi was sprayed with mud! I'm not ever going to get deeply enough into this to buy a mirror ball, etc, but for my purposes, I found I can get acceptable results by taking my background pic into Paint Shop Pro, distorting it to get something that matches the light-probe template, then doing a little bit of tweaking on the result. Thanks again!

Looks really good, Morphy! Congratulations! I really love the shadows and specularity on that second image, especially for the hair. Good work.

Thanks, max... They're good by comparison to my earlier IBL efforts (which were so dire I wouldn't even think of posting them!) But I did those pics yesterday, and now that I look at them again, I can see quite a few things that aren't right. But I think I see some of what I did wrong. For now, I've dropped the idea of a human figure - I'm back to a couple of primative spheres, just to see if the IBL can make them look part of the picture so far as lighting is concerned. This one was done with one IBL and one specular light. For the light probe, again, I just altered the background image in Paintshop Pro. I think it works fairly well.

Yep, those spheres definitely look part of the image. Great composite, and perfect lighting. The only thing is I think the AO (at least it looks like AO) on the bottom of the spheres seems a bit strong. Well, perhaps not too strong, but certainly too "spread". If you can tighten up the AO underneath a bit, it would be seamless and perfect! Don't give up on the human figures either though. No one that I'm aware of has ever perfected human rendering in 3D. NO ONE. Not even the highest end software and professionals. I've seen a few that came VERY close to fooling me, but none that are perfect. :-) Anyway, excellent efforts, Morphy. Keep it going!

Morphy - looks great! Well done.