rendering a building with a city animation...suggestions

[kippu]

well this is the scenario ... i have a big tower in the middle of a city, the building exterior animation has been rendered out, now if i render out the surrounding areas with the same camera path,

 

how do i composite the building within the environment animation, ....

 

how do i mask the building so that it pops up in the right place of that area...or i render the foreground and the background separately ..which might not work because the camera keeps flying around the building

 

any other things that i might have missed ?

 

any suggestions about this project would be helpful

 

thanks

[Arnold Gallardo]

That depends on your render out settings. Most render engines have the capbility to render out alpha channels along with the scene. This is probably the best course of action for you. If not you might need to render another pass with a background color that is not inlcuded int he scene like green or blue or even orange. Then just use a vidoe editing program that has chroma-keying capabilities aka 'green screen'.

 

Something like this is really hard to give tips to without seeing what you have. Also you might wanbt to look into using a camera tracking tool for compositing the foreground and background together aince you already have the camera animation.

[colinsmith]

If there is no dedicated alpha channel output it is probably better to make one yourself by making all your building matterials white and 100% luminous, and all the other buildings matterials black, render the animation pass, and there is an alpha to use for compositing the 2 rbg passes.

 

Pulling a greenscreen matte is not always so easy, and if you are starting out on composting then you might as well use the software to make an alpha since it is no harder to do.