No internal reflections inside Glass material

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74hc595
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No internal reflections inside Glass material

Post by 74hc595 »

Hello,
I have problem with Glass material. In a scene where camera is inside glass object volume I can't get reflections on the surface.
When the camera is outside glass object, reflections work as they should.
I've attached rendered image and simple Blender file with this problem.
Attachments
internal_reflections.jpg
internal_reflections.blend
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B.Y.O.B.
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Re: No internal reflections inside Glass material

Post by B.Y.O.B. »

Reflections of these caustics are SDS paths, which Bidir can not render.
You will need Path + Light Tracing + PhotonGI caustics cache to render them.
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74hc595
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Re: No internal reflections inside Glass material

Post by 74hc595 »

Thank you!
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B.Y.O.B.
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Re: No internal reflections inside Glass material

Post by B.Y.O.B. »

A note though, looking at a debug rendering of just the caustics cache, the reflection on the surface is very dark. I'm not sure what is responsible for this.
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74hc595
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Re: No internal reflections inside Glass material

Post by 74hc595 »

I've tried again, this time instead of bidir I used Path + Light Tracing + PhotonGI, but the effect is nearly exactly the same.
If I invert the setup - place camera above the water, light underwater and change camera volume to air, then water reflections look amazing.
When camera is underwater, the reflections are extremely dark. Maybe it's a problem with glass material being viewed from other side?
Attachments
internal_reflections2.png
internal_reflections3.png
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74hc595
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Re: No internal reflections inside Glass material

Post by 74hc595 »

Also when camera is above water, everything below water is distorted, as it should be, but with camera underwater, things above water are darker, but not distorted.
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Dade
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Re: No internal reflections inside Glass material

Post by Dade »

74hc595 wrote: Tue Sep 22, 2020 1:28 pm Also when camera is above water, everything below water is distorted, as it should be, but with camera underwater, things above water are darker, but not distorted.
Are you setting the camera volume (i.e. water instead of air) ?
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74hc595
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Re: No internal reflections inside Glass material

Post by 74hc595 »

Yes, in the underwater example camera volume is set to water, and in the example with camera above the water level it is set to air. The normals of the water mesh point upwards, interior is set to water, and exterior is set to air. What is surprising, is that while light gets distorted when in passes into the water and creates caustics, but walls above water level in the first image appear undistorted. When camera is above water everything looks ok. I've attached Blender files for both cases.
Attachments
internal_reflections.blend
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internal_reflections_inv.blend
(871.45 KiB) Downloaded 143 times
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74hc595
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Re: No internal reflections inside Glass material

Post by 74hc595 »

I've also tried creating two-sided material with Mirror as back material, but nothing changes.
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Dade
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Re: No internal reflections inside Glass material

Post by Dade »

74hc595 wrote: Tue Sep 22, 2020 7:59 pm Yes, in the underwater example camera volume is set to water, and in the example with camera above the water level it is set to air. The normals of the water mesh point upwards, interior is set to water, and exterior is set to air. What is surprising, is that while light gets distorted when in passes into the water and creates caustics, but walls above water level in the first image appear undistorted. When camera is above water everything looks ok. I've attached Blender files for both cases.
This was tricky to spot:

im2.jpg

You have 3 volumes defined in your scene: "air" (1.0 IOR), "water" (1.33 IOR) and "Volume" (1.55 IOR). And you have two perfectly overlapped volume nodes in water surface material definition:

im1.jpg

with the wrong one (1.5 IOR) connected to the material.

If you fix the volumes, the scene should render as expected.
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