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View Full Version : IBL Rotation to match plate


gangshow2003
04-20-2010, 10:19 PM
Hey all,

Hopefully someone on here can help!

I have been playing around with HDRI's and image based lighting etc but am getting stuck with the rotation of the IBL sphere. Im basically just compositing cg into a still photo, lighting the cg using IBL. When I put the HDRI onto the IBL sphere (working in Maya) obviously the rotation of that sphere effects the outcome of the lighting on the cg object. For example if you have a strong light source coming from the right in reality, when you get IBL going in maya how do you make sure that it is rotated so that that strong light source is also coming from the exact same angle from the right? Is it just rotate the sphere until it matches? As that can be difficult to tell if there isnt a strong obvious shadow to help match up. Or is there some technique that I dont know?

I hope that makes sense!? If not let me know.

Thanks in advance,

Simeon

jhaeusle
04-27-2010, 06:29 PM
Hi,

can´t you use a viewport viewable sphere mapped with the HDRI as a visual example? Then you e.g. could wire the rotation of your IBL sphere to that dummy-sphere and it rotated when you rotate the dummy sphere. This then should work as a setup for other scenes as well.

Unfortunately I´m not a maya user (I´m on 3dsmax here) but I guess this may lead into the right direction. Further on you could link other artificial light sources to that dummy sphere as well (e.G. to get better defined shadows etc.).

You just would have to make sure that the primary light source matches the one of the IBL once and then it should work for others as well...

Probably it helps to use a panorama with a clearly defined sun to calibrate such a scene (e.g. something like the following)

http://www.sachform.de/free_downloads/B05_Final_1000.jpg

I hope this helps and please excuse if this sound totaly nuts when working within maya... :blush:

Cheers,

Jan Häusle
Sachform Technology

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