Shoot refelction for integration of a car in real footage

[fbrandst]

We need advice on a project...definitly a new production field for us. Our client wants to do a real shooting of a city environment and integrate a full CG car. We are used to do everything in CG so we ask ourself how to get the reflections right. Especially when we have moving elements, they need to be in the reflection as well.

Are there any tools or methods to get these moving reflections while shooting??
We had the idea of mounting a panorama cam,for example the pointgrey ladybug2, but we have no experience on how this lines up...

maybe someone has a good idea on shooting matching and moving reflections, in order to integrate a cg car in real footage or an advice how the big studios might do that...

thanks for all ideas...

[Hugh]

Is the car going to be moving or static?
Camera moving or static?

[fbrandst]

Well both should be moving. we want our car to drive in the street, matchmoved to the moving footage. so to speak, we will have moving elements also in the reflection.

[Hugh]

Okay....

If you're shooting it out of the back of a van, you could have a silver ball on a small trailer behind the van. If the trailer and ball are smaller than the CG car will be, there won't be any cleanup needed. You can then get an animated environment map from the moving ball. Getting a track on the ball could be a pain, but it's certainly doable. This would give you pretty much all of the lighting information you'd need for your car...

[fbrandst]

Ok, that was somehow the way we thought it could be done. We will test it...hopefully.


thanks

[wl_kicker]

wow......great idea..but does it necessary use HDRI..? HDRI squence?

[fbrandst]

no, we do not need to use HDRI... do you have a better idea on how to sample the real reflections on set ? the chrome ball right now is our favorite - or we use the pointgrey ladybug2, if that works...

[wl_kicker]

i think use the metal ball maybe have some problem in this case..
two shots still can't match maybe....

[fbrandst]

that's exactly our concern. also the fact, that the resolution might be too small for good reflections. are there any other ideas ??

[wl_kicker]

ok.i have two ways.one is to match moveing exactly.
Do you know Pftrack can model and texture it of the object in you stuff shot.
you can use this way to rebuild street and buildings.the reflection must be matched.but the texture must be not clearly enough.can you make the reflection blur = =!!

second way it's based the first.after rebulding the street by simple plane.for good
defination ,take some great photo replace the txture of the model exported by PFtrack..^^.i don't what about my ideas.... i just a student..without expriences..
i like vfxing..

[Hugh]

I just spoke to one of the supervisors here, and he suggested having the reflection ball mounted directly in front of the camera - as long as it is smaller than the resulting car will be.

He also suggested having, behind the camera, 4 DV cameras pointing in different directions (forward, left, right, up)

[wl_kicker]

oh ..great ..thanx admin

[fbrandst]

Hugh...many thanks...thats a great idea. Now how about matching all these elements. Because we believe, that they simply will move absolutely different to each other. Ok we can try to stabilize them...but the timing will be different.
and then, what about the resolution of the chrome ball? when we mount it directly in front of the camera the resolution might be no problem but then we need a second pass whithout the ball...don't we?? and that pass won't match at all then. the 4 DV cameras are a very good suggestion...we will need to set this all up, and try.
by the way, what camera would you use to shoot the ball to get the best quality out of it ?

to wl_kicker- also a solution we were thinking of, the problem here is, that we want motion in the reflections, meaning, when for example a real car is passing our CG car, we want the motion of it in the reflection. your solution is very good for a lonely street. but when there is motion all around, and your reflection is static, the car will stick out.

[Hugh]

You wouldn't need to shoot it twice, because you'd make sure that the ball filled up less of the screen than the car would end up filling up.

For the ball, you'll want to shoot with the highest dynamic range possible. What's the final thing going to be on?

[fbrandst]

I think we will need HD resolution.
thanks for all the hints !