Interesting Challenge

[smashley]

I have an interesting challenge that was actually inspired by the fxguide podcast covering Real Steel. In that podcast they mentioned in one sequence they had a cgi fighter moving through a live action plate. They shot multiple HDR's on set of the environment to cover the character as he moved thru the shot. That way the reflection would change accordingly to his position. They mentioned they developed a way to blend between the IBL rigs or essentially have a spatial system that would blend to another IBL when an object moved thru the space.

I'm fairly sure this was a Vray show and I was wondering if something like this is possible with the Dome Light IBL method? I noticed that there is no falloff on this light type which would make this quite easy. Is there another way to achieve this? I have a shot with many small objects traveling through a live action plate. I plan on shooting multiple HDR's to cover the room. My plan is that as the objects move thru the room they are lit by the appropriate HDR's spatially. Any help would be greatly appreciated.

-chad

[instinct]

Maybe Jeremy was involved : http://www.chaosgroup.com/forums/vbu...hlight=spatial ?

Kind regards,
Thorsten

[joconnell]

It's pretty much just a case of projecting the hdr images you've taken from set on to geometry that matches the physical shape of the set. You'd pretty much just go to your shoot, measure the set, shoot your HDR's making a not of where you shot the actual hdr from in the set, track your footage using your set measurements and use the track point cloud to build some simple models of the main surfaces in 3d. Camera map your HDR's on to this set geo from the same place you shot them from and you'll get the HDR data almost uv mapped on to your simple set. The HDR values will be coming from the correct place in the set so as your object moves around it'll walk in and out of the various different zones of light that were in the real set.

[smashley]

Sounds like the right concept. Very cool! Thanks for posting! Sounds like something that is difficult without some serious development time.

[smashley]

Your right, that is a totally valid method. We may end up doing something like this, but it's a bit overkill for this particular job. I wish the Vray Dome light had falloff parameters, that would probably work just fine. Thank you very much for all the great ideas!

[joconnell]

The really smart guys from framestore commercials did a combined maya and nuke course on FXphd where they did something similar. Now in their case it was a very very simple shoot inside of an aircraft hanger which was four walls and a slightly arched roof, so if didn't take much to measure and build accurate geometry to match the set. But they did this, shot one HDR inside the hanger and made a note of roughly where they were standing to shoot it, and then a spherical projection with the center of the map at roughly the same spot inside the 3d hangar made the HDR images line up pretty well with the geometry so they were getting more spacially accurate lighting right away. Again this was a really simple case but the theory would be the same for a more complex build - you'd have to be way more careful about what parts of the set will come in and out of visibility over the source of the shot and you'd have a lot more measurements to use to ensure a good line up but it should work!

[rivoli]

this thread by metzger in the maya forum describes a workflow with ptex and mari which may have to do with what you're looking for (basically what john outline a couple of posts above):

http://www.chaosgroup.com/forums/vbu...highlight=mari