Shadow Catcher / Matte Object - Shadows too bright

[RedStar]

So this has been an issue for years now when using the matte object setup in Vray. I am curious if there is a work around or if I am doing it wrong?
The image below is a simple setup using the new dome settings along with an hdri I shot, as you can see the time of day is midday and the shadow on the cgi car is super light.

Now this 2nd image is 100% same everything, except the ground plane is just a white plane with no matte object/shadow catcher properties. The shadow here is perfect, how can I get this shadow to show up on image 1, this way I can still have it be transparent floor to match my HDRI/Dome but also have proper shadow values. I believe this is not an issue in Corona but always has been in Vray. Was hoping with the update of the VrayHDRI they would improve the shadow catcher to work better as well.

[hermit.crab]

I presume it's simply because of the color blending. Does it happen with a full spherical HDRI? Also, the second image doesn't seem to have the caustics contributing to the overall lighting.

[seandunderdale]

Ive had weird results often with the same setup, so Ill be very interested to see the results of this.

[RedStar]

I presume it's simply because of the color blending. Does it happen with a full spherical HDRI? Also, the second image doesn't seem to have the caustics contributing to the overall lighting.

From my understanding the reason is simply because when I make an object "Matte Object" the shadow intensity gets washed out by the HDRI/Background image. This is a problem I have even when rendering cars into backplates. So to avoid this I have to always colorgrade my ground texture/exposure to match backplate as close as possible. The beauty of the Corona Shadow Catcher is that it somehow makes the shadow proper on a backplate/hdri which is wonderful. Was hoping with this new update Vray can have something like that? The Vray Matte Object method for Backplate/HDRI has always been and issue for shadows not being proper. Nothing to do with caustics or anything, its just an issue with the way matte object takes on shadows.
Also first image has no caustics, my HDRI was a bright day shooting at the salt flats so ground has extremely values which is causing the shadow to be blown out, however in real life when a shadow falls on a surface it should be dark and override the exposure of a surface under it which is not the case here but is the case when I just use a normal plane.

Hope that makes sense?

[seandunderdale]

I think I had the same problem a few yrs back. Never really solved it. I render my shadows baked into the backplate now, or onto a white floor and multiply on in post.

https://forums.chaos.com/forum/v-ray...colour-problem

[hermit.crab]

Could you attach the scene (a sphere instead of the car would do) and hdri here so we can take a look?

[RedStar]

Could you attach the scene (a sphere instead of the car would do) and hdri here so we can take a look?

Hello! I went ahead and found another hdri thats free online, the one I used in my assets is something I sell to clients for commercial usage so I cant share it public.

https://1drv.ms/u/s!AnEPb6dOabGJ1BQO...Q7ysq?e=nUjGkv

With that said, I was able to recreate the same issue no problem. Attached is a zip, contains images and scene files.
Scene File labeled Matte Object - I click the shadowcatcher icon in Vray and applied a white material. The results are 100% as is.

Scene File labeled Solid - I undid all the matte object properties and hit render. The results are 100% as is and the more realistic/favorable shadow.



Thank you in advance for taking the time to show interest in this. Has been a problem for yeras and would be amazing to finally have a solution or a software update that would allow a solution for future.

[matthew999]

Random question/thought.... Are u rendering with IPR or production render. I found that using IPR shadow always looked washed out but when I switched to bucket it was much darker.

[hermit.crab]

Thanks for the provided scene. The issue in the attached scene is related to the "Finite Dome". It seems matte shadows are rendered as if an infinite dome is present. I've logged the issue (internal bug-tracker id: VMAX-12408 ) for developer investigation.
I am not certain if this is the case with the original scene, though. Is the VRayDome there finite?

[seandunderdale]

I had these issues too in Vray 5 and previous versions, none of those had a finite dome, but I use Maya.

[RedStar]

I had these issues too in Vray 5 and previous versions, none of those had a finite dome, but I use Maya.

Agreed! This has nothing to do with the new Dome Feature. This has been an issue with the Vray Matte Object setup for years and years, which is why I never use it. Was hoping this release would have finally fixed it but it seems not.
Maybe we can get Lucky and Vray7 can have a fix like the Corona Shadow Catcher or something lol.

[seandunderdale]

Wondering if there was any info on this issue?

[RedStar]

Wondering if there was any info on this issue?

I am starting to think they don't care to focus on getting this resvoled or accept that there is an issue. The answers I see above seem to hint we are setting up something wrong and it functions as it should, when you and I both know thats not the case.

Btw, with more and more testing, I did notice one bypass Sean. If you were to create a additional sun source like a vray light then you can make the shadows proper, so it defats the whole purpose of using an HDRI for sunlight since the hdri creates an awful visual of shadow/ground.

[fixeighted]

EDIT: Editing for being an idiot

I found a similar hdr to the salt flats for this one.

Something must have made me think it wasn't doing what I wanted but it clearly is, so panic averted lol