Hey all,

Does anyone know why my background images render funny with photometric lights?  In my current project it won’t render at all. I have my image in an output map with the output cranked all the way to 10,000 and it still doesn’t look the way it should.  Other times, when the image did render it came out extremely dull and flat.  I know it is possible because I got a file from someone else who pulled it off, but I can’t figure out what they’re doing that I’m not.  Any ideas/workarounds?

Thanks

Have you tried asking the one who gave you the file that works?
Maybe post that file here for some review.

Max 2012
Windows 7 64 SP1

Do you use photometric exposure control? If yes, what is your EV? Try setting it to 0 and then testrender if the background shows up. Might be that 10000 output still isnt engough to compensate a high EV Value. The dullnes might result in not gamma correcting the background image…

It’s hard to say for certain without seeing anything, renders/settings, but I expect it’s to do with the exposure control and gamma settings.
I’m assuming you are using mental ray, instead of putting the BG image in an output shader try the mr Env/BG Camera Map shader, it has a Multipier and Reverse Gamma Correction built in.
It would help to know your renderer, exposure and gamma settings.

I am using Mental Ray with the MR Photographic Exposure control default settings.

What about your Gamma Settings? Have you tried the mr Camera Map yet?
Another way, instead or increasing Ouput is to alter the Physical Scale of the Exposure Control. Some info on that:-
http://mentalraytips.blogspot.com/2008/02/why-does-mental-ray-render-my.html

I think this will help:

http://mentalraytips.blogspot.com/2008/02/why-does-mental-ray-render-my.html

You also might wanna chekc this out:

http://forum.german-mentalray-wi...ighlight=background+image
(It is in german though...)

Hope this helps ;)

Actually the integration of a background image when using photometric exposure control is a bit of a pain in the *** process. Just one the millions of issues that should be (in my opinion) adressed in further versions of max (and mental ray)…

Actually the integration of a background image when using photometric exposure control is a bit of a pain in the *** process

It is difficult to get the BG to render exactly the same as the original, the real solution is to post composite the render onto the BG footage.

I forgot to mention that I have done away with the output map.  It was only done briefly as an experimental solution.

you can also try using the Unitless value instead of the Physical Units option in the mr Photographic Exposure Control.
I usually start at about 50000 and go up to about 80000 in some cases.

Yassina, Will this change the intensity of the lighting system at all?  I have been reluctant to change the settings for the exposure control because the last time I screwed with them, the whole scene got blown out big time and I had to merge everything into a fresh scene to fix it.