Surface reflections?

RexRed

How do I make only certain things i.e. lights, gobos or objects not reflect in a mirrored surface while still letting other objects reflect?

 

Anyone know a good tutorial on this?

fastbike1

Can't do this in Iray. It is a Phisically Based Render engine that is simulating actual light and surface behavior. You have this capability in the 3DL engine.

TBorNot

Well, yes, and no.  For example, people insist you can't have soft Iray shadows and they are correct, if you limit your light source to realistic parameters.  That's the weakness of the argument, realistically simulating an unrealistic input is, by definition, unrealistic.  Use your imagination, I bet you can figure out a way to fake out the engine.

Richard Haseltine

TBorNot said:

Well, yes, and no.  For example, people insist you can't have soft Iray shadows and they are correct, if you limit your light source to realistic parameters.  That's the weakness of the argument, realistically simulating an unrealistic input is, by definition, unrealistic.  Use your imagination, I bet you can figure out a way to fake out the engine.

Soft shadows require a non-point light source, easily done in Iray even witth the standard lights.

TBorNot

Yes, but you can do it with any light source, which is the point.

Richard Haseltine

TBorNot said:

Yes, but you can do it with any light source, which is the point.

I'm not folllowing - soft shadows from a non-point light source is physically correct, so it doesn't say anything to making a light not reflect in soem surfaces (while still, I assume, illuminating them) but reflect in others.

TBorNot

I got the idea from a user comment in the forums.  To make a light "soft" you need to get close and make it big.  Outdoors, this isn't possible in the real world, but what if you make your spotlight the size of the apparent moon?  It's only possible in our virtual world, but that's OK.  Here is a scene lit by one spotlight in the same position.  One is the default size, the other is really really really big.  :-)

 

TBorNot

For reflections, it's the same thing.  In real life, a photograph is one picture, but we don't care in our world.  Say you have a mirror, and you don't want that chair to reflect.  Same camera, two pictures.  First is the whole room with the chair visible and reflecting in the mirror.  The second is a picture with the chair set to invisible and not reflecting in the mirror.  Crop the mirror out of the picture with it missing and put it over the mirror in the first picture where it appears.  Movie magic.  :-)

TBorNot

The vampire test.  :-)

Sven Dullah

TBorNot said:

The vampire test.  :-)

Heh, one good thing about 3Delight...no need for postwork or rendering twice:))

TBorNot

Shame there's no like button in the forums.  :-)