Wrapper shadow and reflection affect question- how to keep shadows and reflections from object only not flood base material

[berkheit]

I am trying to place an object over an photo image and want to have the shadows and reflections from the object but not the rest of the base material so no other reflections from lights on the material or from the background. I keep getting this result which is not what is desired. I really just want the reflections from the objects and the rest of the ground plane to be transparent. Thank you for the help with this issue.

[monksalve]

Not sure I fully understand. Is your wrapper material casting a shadow? Don't think it should. From your image, I would make a material for the grey base and then use a wrapper on that material with 'Matte' and shadows turned on. You can control the reflections and color of the wrapper from the original material. I also use black alpha so it doesn't save the base in the Alpha channel, just the reflections and shadows.



If you don't want the shadows just uncheck shadows on the wrapper. If you don't want shadows or reflections of a specific material, turn them off in the materials raytrace properties. You might have to add a raytrace module depending on what version of v-ray you are using.



Hope this helps!

[berkheit]

Hi thank you for trying to help and I am sure I am missing something obvious but I looked at my settings and they seem to be identical to yours but I am still getting a result like this. Is maybe the environment or the lighting? Thank you again for helping me to understand.

[berkheit]

error wrong post

[berkheit]

So I was able to remove the big reflection when I turned off my dome lighting? Not sure why that works the way it does but, I am guessing it has something to do with the background and how dome lights work. I am able to get the shadows on a transparent base material, but no reflections. I have made my base material very reflective but it will not render any reflections at all when I change my alpha to -1. Sorry there must be something basic I am not understanding about how the wrapper and base material operate.

[monksalve]

Hmmm...yeah, think you might be running into indirect lighting issues. Any way you could upload a simplified version of your scene?

Dome lights tend to make weird errors once you try to control the shadows. Maybe that applies to reflections too. Have you tried using the environment slot instead of a dome light? Another issue could be the light being visible or not and the setup of your background color.

We were just talking about this issue with domelight last week: https://forums.chaosgroup.com/forum/...isable-shadows

[berkheit]

So this is a simplified scene from afar so you can see all my lighting. Plus 2 alpha settings so you can see there are reflections in the material when set to alpha 1. Thank you for your help with this.

[monksalve]

Think I get what you want now. Reflections from only the objects, not the environment or lights. A little dense on my part.

I tried turning off the affect reflections in the lights or domelight and it seems to do the trick. Uploading ref images and my mock up.

[berkheit]

Thank you this looks encouraging I will give it a try and leave you a post on how if it works out.

[berkheit]

Hello I saved your scene and rendered and still did not have reflections and then I discovered something odd I don't understand but maybe I should. When I rendered with my CPU I was able to get reflections and shadows but when I switched to GPU rendering the reflections disappeared. My gtx970 is a bit old but did think that would be an issue. Is there a setting under GPU I am missing that I should be checking to get both reflections and shadows or maybe I should just not worry and use the CPU for rendering? Either way i am glad to feel like I have something I can do affect the reflections as I was starting to feel like I was loosing my mind and could not get anything to show reflections. Thanks again either way it is great to have some help with this. OH, I am using the latest V-ray by the way in case you were wondering but had the same issue with the last version as I just upgraded last week to see if the newer version could help me figure this out.

[monksalve]

Interesting. I don't really use GPU rendering so had not ran into this. Just gave it a try and yup, it does not render reflections on the wrapper and shadows don't work for the dome light on GPU. Looking at the documentation it seems like the Wrapper material is only partially supported on GPU. Not sure what that means but probably explains the problem.

https://docs.chaosgroup.com/display/...orted+Features

Looks like you'll want to stick to CPU rendering if using a wrapper

[berkheit]

Well this has been very helpful for me thank you, and hopefully anyone else who may be struggling will be able to find this and not waste tons of time rendering and rendering again and again like I did trying to crack the problem. I will be able to finally move forward. Best of luck to you and be well.

[Micha]

So far I know the wrapper shadows works for GPU per dome light only, no simple environment.

In the last time I don't needed reflections and so I don't miss them. I did a test now and it looks like in GPU mode the wrapper works per dome light only and without reflections. I hope the GPU team get the missing functionality working.