How to render only certain elements of a scene for post production

[Guest dialog]

Hey quick question on the quickest method to do this. I am looking to add a bunch of cars into my render. The original render didn't have them. I know I can re-render out the entire scene again with them and apply an Object ID to them, but I am wondering if I can JUST render out the cars with all of the correct reflections and lighting from the scene without seeing anything else.... need to keep the render times down...any suggestions

[notamondayfan]

just render regions of the cars, and paste them into your original comp, otherwise it gets complicated with shadows, light, etc if you start messing around with hiding / making invisible parts of your scene.

[Guest dialog]

I ended up just rendering out the whole scene again with object IDs. FOr the future though I wouldnt mind figuring it out for animation stuff and compositing.

[JDx]

Region render?

[Guest dialog]

Region render?

 

I dont want to region render over all the areas that have the cars...this would make a bunch of small region renders and wouldnt work for an animation. Quick fix yes, but I know there is a way to do it as I have seen it done...just have no idea how haha.

[Scott Schroeder]

Matte materials or in Vray use the matte properties in the Vray Properties menu.

[Guest dialog]

Matte materials, all of them for the various engines allow for reflections to show in the matte. You apply a matte material to everything but the cars, and an extra one that includes reflections on things you want to reflect.

Oh ok. Not sure I grasp the extra material. SO lets say I want a ground shadow on the road... THe cars visible and nothing else. ALl the downtown buildings will get MAtte materials (I do want them to show up in the car reflections) and what material for road to have shadows but still not see road...

 

How do the alphas of the mattes work...do I need to change any of that stuff to -1 or anything?

[achilliesgreek]

I think this may help you..

 

if you want to render only a particular object along with the lighting etc.. this can be done by right click on the objects that needs to be excluded from the render and uncheck the visible to camera option..

[Guest dialog]

I think this may help you..

 

if you want to render only a particular object along with the lighting etc.. this can be done by right click on the objects that needs to be excluded from the render and uncheck the visible to camera option..

 

I could use this way...

 

This wouldn't work if there were elements in front of the cars though. Especially animations.