Interior Mode vs. HDR Brightness Test

[Speedster]

Hi all;

I doubt that this will advance the State-of-the-Art, but it is interesting.

I've been curious if setting the HDR Brightness to zero would be the same as rendering within an enclosed volume.  We know that the Interior Mode is optimized for physical lights within an enclosed space.  But I'm thinking that setting the HDR Environment Brightness to zero would accomplish the same thing.

So I did this simple test.  There is a ground plane and a shelled out box, both with matte black paint for just a bit of reflected light.  HDR is the startup, but does not apply in this test.  The light is a sphere with Diffuse Area, centered and just above the geometry, and hidden from the camera.

The captions explain each rendering.  Any comments?  Understand that these are all very simple materials, and other impacts may be seen on complex materials like brushed steel or leather.

Interesting, nevertheless...

Bill G

[DMerz III]

Here's what I noticed:

- HDR set to Zero brightness basically makes an all black scene. The enclosed space with matte black paint actually gives us more detail.
- The "back wall" is definitely catching some light in the 1st image helping to define the shape of the pyramid.
- Also Interior Mode seems to work better in both examples as you expected; less noise.

What were the overall sample rate for Advanced Control, and do you know how long that render took?

[richardfunnell]

That is a good exercise on the difference!

My recommendation would be to use Plastic instead of paint, and try out different diffuse/specular colors. Or even a simple Diffuse material (with varying gray values) will show the results pretty dramatically. The Interior mode takes advantage of all that extra light bouncing around, and this is a great scene to see the results.

[Speedster]

I agree this is getting interesting!  I'll try your ideas, Richard.  And yes, the matte black does of course impact reflected and cast light as dmerziii noted.  FYI- for the Interior renders I used Max Time of 10 minutes on 32 cores.  Could have been way less.

For these two I hid the box (volume) and ground plane.  The main thing I see is that #5 has less noise.

My main question was whether zero brightness would be the same as an enclosed (water-tight) volume. That is, no light = enclosed dome.  It appears it may be.

Bill G

[Speedster]

Wow!  Here's the "tail of the tape", as they say.  Wish I had tried this first!  It's my old Gould Compound model, with 32 IES lights.  442 MB, 5,541,218 polys.

First image is "Product Mode", HDR at zero.  Rendered with Advanced Control, in 18 minutes on 30 cores.

2nd image is "Interior Mode", HDR at zero, Maximum Time of 30 minutes on 30 cores.

'nuf said!

Bill G

[bdesign]

This is awesome, Bill! Great study 

Cheers,
Eric

[DMerz III]

Wow, even the difference in the materials (mostly the leather specular) is vastly apparent.
This is a great study, thank  you for sharing with us.