Announcement

**aHipLooffpeafe52** · 08-01-2011, 06:07 AM

**inbalto** · 08-01-2011, 07:09 AM

Re: rendering only reflections of a material?

I can only read English or Hebrew... can someone help in those languages?

**skurl** · 08-01-2011, 07:31 AM

Re: rendering only reflections of a material?

lol

**andybot_cg** · 08-01-2011, 06:35 PM

Re: rendering only reflections of a material?

Hi Inbal,

There was a post recently about how to render reflections as a separate layer

You can render those glossy materials ... separate using the VFB channel option and selecting only raw reflections and reflections in a second render pass. You should get a mostly black image with some color and highlight splotches here and there. What you do with this is simply import it into photoshop with your final render and change the blend opacity setting to "screen."

You could run this rendering at 1/2 of your full size rendering (to save you the 19 hours of rendering! But you need to save as png or tif since the exr can't save channel info) and then scale it 200% to bring it into your original rendering.

*edit: also, you can change the material ID color of the material that didn't get the reflection. You can then select another channel - Material ID - and use that selection area to mask the reflection to just that one material. It is useful to be able to cut out only that material so you can adjust the transparency of the reflection. (I find the reflection channel comes out too strong compared to the original.)

Hope that helps.

Andy

**inbalto** · 09-01-2011, 05:12 AM

Re: rendering only reflections of a material?

Thanks, the problem with that is that it doesn't reflect the environment...

If anyone is following my threads around this forum (each one poses a new problem with the same $%#$%$^ model

so my last render: 5000*2754 pixels took about 40 hours!!!! yes yes: almost 2 days!
3/4 through I realized my floor was lacking the reflections and some other light stuff that were too bright so I kept going till the end but then started over: this time with the new beta version that gave me the ability to use the DR spawner without it crashing the model, and I turned many lights that were in the scene but not contributing to the specific view I was rendering, and the render ended over night... (gasping for some free-rendering air

I have a new problem (but ofcourse) but that for a new thread

**andybot_cg** · 09-01-2011, 10:16 AM

Re: rendering only reflections of a material?

Inbal,

This post may help if you have a lot of area lights in your rendering.

http://forum.asgvis.com/index.php?It...0&topic=5208.0

and here's a snippet of thomthom's response in this post giving an example

Then I inserted a rectangular light covering 90% of the ceiling where I rendered the same scene with various subdivs.
2 subdivs: 26.4s
20 subdivs: 27.3s
200 subdivs: 1m21.2s
2000 subdivs: (still rendering after watching one Mythbusters episode) {1h33m4.8s - about two Mythbusters episodes}

What I also notice with the various test renders is that I can't really see any difference in them. Though this is with a completely empty room.
But I see that I can reduce the subdivs in the scene I mentioned in the OP drasticly. Knowing that the number of ray is the square, I see how much impact even 1 subdiv makes. Now I can place them more smartly.

The other thing I could point out that may help is to either hide or turn off layers/ geometry that you do not need in a scene. I found that out a little while ago.

http://forum.asgvis.com/index.php?to...55938#msg55938

Also, this is a good example of why it is worth doing a small res test rendering before starting a very high res rendering. You can catch these problems sooner. I've been burned like that a few times too! I end up doing a lot of post-processing when it's too much of a pain to re-do a day long rendering... :P

-Andy

**inbalto** · 09-01-2011, 12:13 PM

Re: rendering only reflections of a material?

Wow, great threads Andy!
I wish it was all centered in one place.. this forum have some dark corners with really useful information. thanks for sharing

**andybot_cg** · 10-01-2011, 07:49 AM

Re: rendering only reflections of a material?

Glad to share. I agree it can be very hard to find specific information on this forum. Even when you know the specific terms you are searching, it can be hard to find a thread that's actually pertinent and helpful. I've started keeping a bookmarks folder of some of the more useful threads, but there is still a whole lot more good stuff buried in the forum. I do appreciate having the tips and tricks section, but even that can be hard to wade through...

Andy

Announcement

rendering only reflections of a material?

rendering only reflections of a material?

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment