Render Region question...

[AJLynn]

I've done a render at a high resolution that took a long time, and messed up one material on one object. Can I render region (or even render object) to Picture Viewer in a way that will let me do just the part I want and patch it in Photoshop? I can't seem to find that, though I'm sure there's got to be a way...

[Sindala]

you could make a foreground object and attach a material with an image representing the cutout with black and white as an alphachannel.

I do it a lot actually.

[AJLynn]

Interesting workaround, I'll try it. Thanks.

[Ernest Burden III]

This idea originally came (to me, anyway) from STRAT.

 

Simply place a polygon in completely front of the camera and then subdivide so you have a grid. Delete a poly or two to open up a hole, slide the points to fit nicely and add a material that has no channels active, or just a black color. Make sure it has all GI and effects off. Re-render (remember to rename the output file so you don't over-write your original!) any you're done.

[AJLynn]

Since I was using AO, Dick's suggestion was perfect (foreground objects have no geometry for AO). What would the comp tag be if I wanted to do it with geometry - not seen by rays?

[Ernest Burden III]

What would the comp tag be if I wanted to do it with geometry - not seen by rays?

 

Not seen by rays, GI, AO, not cast or receive shadows, just be seen by camera.

 

I guess either will work.

[edub]

in the Render Settings>Options there's a box to "render active objects only". you just have to select your object(s) you want rendered, and have this box selected.