View Full Version : Exclude Objects from Final Gather?

05 May 2009, 08:52 PM
I'm rendering some images of stents, which is basically like a cylinder made of chainlink fence.
As I mentioned in a previous post, I like to place a black semi-transparent plane down the middle of the stent to make it easier to read. In the MR section of attributes for the plane object, I have everything turned off except Transmit Transparency. The AE has options for FG Gather and FG Receive, so I would think that I could exclude the object from FG calculations, but that is not working. As seen in the attached image, the transparent planes are included in the FG calculatins, causing a black glow around the objects. The stent in the lower right doesn't have a plane inside of it, so there is no black glow around it. Any suggestions for fixing this?

Also, I have the transparency for the plane set to 100%, yet it still appears quite dark, so it seems I'm doing something wrong on that also.

Thank much in advance.

05 May 2009, 09:05 PM
If you want a object that don't block the rays you can use this script attribute:

addAttr -ln "miFinalGatherHide" -at bool yourShape;
(Change the word yourShape, with your Shapenode of object)

Select your object and run this script, from the script editor and automatically you see the attribute Mi Final Gather Hide, on the extra Attribute of your shape.

05 May 2009, 02:47 AM
I followed your instruction, and the attribute was added to the shapenode, but it didn't work...
I rendered it w/the new attribute enabled and disabled. See the stent in the lower right.
Any idea why it would fail?

05 May 2009, 07:15 PM
if that attribute doesn't work you can also use mip_rayswitch to remove an object from final gather

you need to enable production shaders to do this, i'm sure there's plenty of threads on how to do this already and i know zap's blog has detailed instructions

then create an mip_rayswitch shader for the object you want to take out of final gather, connect that object's original shader to the rayswitch's "eye" input, and connect an mib_continue shader to the rayswitch's "finalGather" input. mib_continue is just an "ignore me" shader. then assign mip_rayswitch as your object's material.

here's a better link actually:

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05 May 2009, 07:15 PM
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