Urgent: Shadowcatcher groundplane being reflected in object not behaving as expected

[Art48]

Edit: I just noted that the reflections in the sphere also dont even match up properly with the background. It is strange. I feel like I am just missing one button.

Hi,

If someone could have a quick look at the basic scene I set up here which is not behaving as expected.

I want the most basic thing: An object (a chrome sphere in this case) lit by an HDRI, casting a shadow on a matte groundplane and the shadow on the matte groundplane being reflected back into the chrome sphere.

Now I think I got a working setup here but for some strange reason two unexpected things are happening:
1) It seems that the groundplane makes the HDRI brighter in some places, difficult to describe. See images attached.
2) I cannot see the background (being the visible HDRI dome light) anymore as soon as I unhide the matte object "Groundplane".

steps to reproduce:
1) Open scene and render camera view. Result: Everything is as expected.
2) unhide object "Groundplane" and render again. Result: see the above mentioned two points.


3ds max 2016
VRay 3.60.03

[Art48]

When I enable the secondary matte environment with the HDRI map inside it, the reflections line up but the other issue (black background) persists, the brightening is gone now although it got replaced by a sudden cutoff of the groundplane reflection into the HDRI reflection...

[kosso_olli]

The HDRI in the domelight has to be instanced to the standard 3dsMax environment slot. Otherwise it will not work, you will always see the black ground plane. Check invisible for the domelight, then. Also, make sure that the domelight multiplier is set to 1. If you want to make the HDRI brighter, use the multiplies in the VrayHDRI node.

[Art48]

The environment slot workaround works. All the other points you mentioned are correctly set in my case. The strange brightening of the matte groundplane (or the sudden cutoff also) still is an issue tho. I worked around it with a distanceTex to make the groundplane fade into the background after some distance. It kinda works, but only kinda. I can't believe if I'm just too stupid or setting up this really basic scenario properly is a pain in VRay/3ds max?

[kosso_olli]

Is this the result you are looking for?

[Art48]

Yes exactly! Is it with ground projection enabled? The background looks distorted

[kosso_olli]

It is indeed. Otherwise the projection for the ground is out of the camera frustrum, which is why you get the cutoff. It starts to work the further away you are with the camera from the ground. Ground projection avoids this.
Also, your setup for the material of the plane is overly complicated. There is no need for a copy of the HDRI in the diffuse slot. The shadow catcher only needs a VrayMtl, the shadow catcher button takes care of the rest.