Shadows problem through the glass

[Karonte]

Hi All. I have a strange issue.

1) i create a simple box for the ground ( vray material)
2) create a simple plane for the opacity ( vray material with map in the opacity slot)
3) create a box for the glass ( simple vray material with refraction on)
4) create a Vray light

I cannot see the shadows through the glass. Can someone help me?
It's very strange...
Do you have the same problem?
The 3d cylinder shadow is visible. I tried also without opacity, putting the map in the refraction slot but i have the same problem.

Vray 5.3

[fixeighted]

Can you attach this scene to investigate?

There's no reason fo this not to work unless you maybe
changed some setting inadvertently, though I can't imagine what right now...

[Karonte]

pes.rar here the file zipped.

[vladimir_krastev]

Hi, thanks for posting. The issue is not reproducing in a new simple scene:



In your scene you seem to have used a software called Verge 3D. Please rebuild your scene without it and this should solve your issue.

[bardo]

This is my attempt following the Karonte first post.


And probably I've found the reason...at least the setting that cause this.
That kind of result is the same if you set the opacity mode both "normal" and "Stochastic".

If you set as "Clip" it should works correctly.


Here my scene (3dsmax 2022 + Vray 5.2.3)
trasnsparency.zip

[bardo]

Hi, thanks for posting. The issue is not reproducing in a new simple scene:



In your scene you seem to have used a software called Verge 3D. Please rebuild your scene without it and this should solve your issue.

As you can see in my scene, it seems that there is something strange with that opacity modes.
They modify also the mesh shadow that overlapping the opacity one (the cilinder in the middle of the opacity plane).

[fixeighted]

Thanks.

So, for a reason I'll leave the devs to explain, this occurs when the bitmap filtering is at default 1.0, so lowering that will fix it.
Well, it fixes it in that the shadow seen through the glass matches the shadow on the ground on the opposite side (very weird behaviour when at 1.0).
It seems it's linked to using an area light.
Switch to a sun and there isn't an issue with the filter at 1.0.

Only a partial solution then, but at least that

[vladimir_krastev]

The image from Karonte's first post has no shadow at all behind the glass from the plane with opacity map.
This issue, as far as I can tell relates somehow to Verge 3D and it is not a V-Ray issue.

There are minor differences in the shadow with different settings of the opacity mode and bitmap filtering.
From the docs:

Opacity mode – Controls how opacity is sampled. For more information, see the Opacity mode parameter example below. This parameter is not available when the renderer is set to GPU.

Normal – (Legacy) The opacity map is evaluated as normal: the surface lighting is computed and the ray is continued for the transparent effect. The opacity texture is filtered as normal.
Clip – (Very fast) The opacity texture is not filtered and it is clipped to either fully opaque or fully transparent based on the mid-point value. Useful when there are many transparent surfaces one behind the other like leaves.
Stochastic – (Optimal) The opacity texture is filtered and the surface is randomly shaded as either fully opaque or fully transparent for a correct average appearance.

Clip vs Stochastic


Clip blur 1 vs Clip blur 0.01


Stochastic blur 1 vs Stochastic blur 0.01

[bardo]

There are minor differences in the shadow with different settings of the opacity mode and bitmap filtering.

Ok, but why the filtering and opacity mode affect also the full opaque mesh that is near to the opacity plane?

[Karonte]

Thanks to all guys. I will try your solutions. I cannot unistall VERGE because i use it for some works.
The very strange thing is that i try with Corona render and all seems to work even with Verge installed ( verge is a webgl exporter, not a renderer ).
Regards

[fixeighted]

[QUOTE=vladimir_krastev;n1200099]The image from Karonte's first post has no shadow at all behind the glass from the plane with opacity map.

Not quite the case I'm afraid, though only for argument's sake, as there is a workaround. The shadow is there and it is extremely faint but you can see it in the attached.
If you 'only' set the bitmap blur to minimum then the shadow is there as it should be. That is the only change I made in the images here.
The Verge plugin appears to have nothing to do with it as far as I can see.

[vladimir_krastev]

The shadow is there and it is extremely faint

You are right. I will dig a bit deeper and get back to the thread.

[vladimir_krastev]

Hi, I did a few more tests.
The shadow is definitely different with the different settings mentioned above.
Here is a comparison between VRayBitmap and Bitmap nodes for the opacity texture:



In some cases the shadow almost disappears. The workaround is to use clip mode for the material's opacity instead of stochastic or reduce the bitmap's blur. .
I will check if this behaviour could be improved or not.

[vladimir_krastev]

Hi, the issue is reported as bug in our internal system (VMAX-13943). We will notify you when the fix is ready.

[bardo]

Will this be fixed both for Vray 5?