any way to get reflection on matte object?

[lukx]

hmm I though that with those settings alpha channel should also take into account reflection:



but no

what I'm doing wrong?

[joconnell]

You only get a matte for the shadows unfortunately. You could use import your render into your compositing software twice though, once with alpha for the object and a second time ignoring the alpha so you get the full image with the reflection. Add or screen the reflection layer over and it'll look halfway decent, otherwise you're looking at making a custom matte. Vray can't pull an automatic alpha as of yet unfortunately - in the case of this particular render it wouldn't know if the environment that's being reflected (which in this case is the default max black environment) should be included or not. Maybe there'd be a way that Vlado could make a render element where if a reflection hits an actual object it'll render white in a reflection matte and black if it hits the environment?

[vlado]

You can use the reflective occlusion options in VRayDirt to create a reflection mask; you can even plug this into a VRayExtraTex render element.

Best regards,
Vlado

[joconnell]

Result! Cheers for the tip Vlado!

[lukx]

woho ! Thanks Vlado... VRayExtraText was also showing reflection of everything in the scene but the vray dirt setup gave me the result I wanted (maybe it will be helpful for others) so here's how I set it up:

[vlado]

Hm, that's an interesting place to put VRayDirt

Best regards,
Vlado

[lukx]

oh btw for object that receives reflection I used plane with Refraction pure white, this is why its transparent in alpha.

[vlado]

Nice trick

Best regards,
Vlado

[pixela]

I tried this but I cant get the reflection mask as you have it.
Is it possible to post a sample scene with a teapot and a plane?

[simmsimaging]

Vlado, would you mind explaining a bit more what you were suggesting with Vraydirt? Im not sure how to implement the idea, and what Lukx has works for him, but looks like something different to me (i.e his result is not dependent on the Vray dirt part of the trick)

B

[rivoli]

I've done what vlado suggests a couple of times, plugging the vraydit map into an extratext render element.
I didn't put the dirt map in any slot of any mat, just plugged directly into the extratext (of course brdf type and reflection glossiness had to match the material which reflections I needed to mask). as lukx says, the render element then apply the dirt map to all objects in scene, but playing with the alpha contribution you can easily fix this.
the only thing that bothers me a bit, is that the reflection occlusion of the dirt map it's still dependent of its radius. this affects the mask for the reflections in an arbitrary way, and you can end up with a mismatch between mask and reflections. what seems to work for me, is setting a very large radius, but I'm not sure this is the right way to go.

[vlado]

the only thing that bothers me a bit, is that the reflection occlusion of the dirt map it's still dependent of its radius. this affects the mask for the reflections in an arbitrary way, and you can end up with a mismatch between mask and reflections. what seems to work for me, is setting a very large radius, but I'm not sure this is the right way to go.

Yes, it is

Best regards,
Vlado

[rivoli]

well, it's good to know I came up with a working idea. for once
cheers for clearing that up vlado.

[lukx]

sorry for delay I don't know why but I don;t receive notification on my e-mail after subscribing to the thread... I will post my scene tomorrow, (vray busy rendering .

[pixela]

sorry for delay I don't know why but I don;t receive notification on my e-mail after subscribing to the thread... I will post my scene tomorrow, (vray busy rendering .

Thanks, looking forward to it =)