Camera match question - Gray Card

[kwok3d]

I'm working on a camera match project and curious to know, if I want to match the camera exposure and white balance to the photo with a vray camera (say I don't have the camera data from the photo) - Can I put a gray card in the site, take the photo, then either create a gray card in 3D or do trick in photoshop? I'm just trying to match the exposure and color temperature as close as possible. Sorry for dump questions, please advise. Thank you in advance.

[dejaVu]

I don't think it's as straightforward and simple as that.
Besides camera lens and settings there are many other factors that would affect the match.
Lighting and atmospheric conditions would play a very significant part.
Your best bet would be to use the VRaySun and Sky, gray card and camera exposure as a starting point only.
You will then need to tweak some of these parameters until you get a match.

[3ddesign]

I've done this many times before and it works quite well. If you use a true 18% gray card like the Kodak R-27 and use a 3D gray card with a Vray material with 114 RGB value the two should match as long as you set up your Vray camera and lighting correctly. Tweaking can be done in Photoshop using Curves and the gray eye dropper to match the real and virtual cards.

[kwok3d]

Interesting. Let me give it a try. Thanks.