[BUG] Glossy transp mat getting way too dark

[PureSpider]

While rendering my jug for the jug competition, I noticed that with later versions than 1.1.14 (which I usually use for rendering), glossy transparent materials get very dark.
This is the material code:

Code: Select all

    <medium>
        <name>MedSimple_Glossy_Glass</name>
        <precedence>10</precedence>
        <basic>
            <ior>1.41000</ior>
            <cauchy_b_coeff>0.00000</cauchy_b_coeff>
            <absorption_coefficient_spectrum>
                <rgb>
                    <rgb>0 0 0</rgb>
                    <gamma>1</gamma>
                </rgb>
            </absorption_coefficient_spectrum>
        </basic>
    </medium>
    <material>
        <name>Simple_Glossy_Glass</name>
        <glossy_transparent>
            <internal_medium_name>MedSimple_Glossy_Glass</internal_medium_name>
            <exponent>
                <constant>100</constant>
            </exponent>
        </glossy_transparent>
    </material>

See attached picture for reference.

[Polinalkrimizei]

Yes I am having the same problem! What's wrong?

[fused]

its a bug, obviously. well have to wait for it to be fixed...

[Polinalkrimizei]

Is there a chance that it is gonna be fixed for the free versions of indigo? PLEASE Ono...

[suvakas]

Same tonemapping, same scale, same everything?
I'm asking cause i've not seen this kind of issue before and tonemapping seems to be different for 1.14 version (on your image i mean). Like linear vs camera tm on others or smth like that.

[edit]
Tested the glossy material you posted on my water jug with 2.06. I see nothing wrong with it. Seems perfectly fine to me. So I'd say it could be your scene setup, maybe?

[CTZn]

Is it really a bug or a correction ?

Refering to the rendered tone only, that could as well be a correction... We just don't know, do we ?

If it's a bug then it's aknowledged by now. But if that's a correction then it is wanted, in wich case you want to correct your materials in turn

[PureSpider]

Same tonemapping, same scale, same everything?
I'm asking cause i've not seen this kind of issue before and tonemapping seems to be different for 1.14 version (on your image i mean). Like linear vs camera tm on others or smth like that.

TM and scene setup it 100% the same!
Maybe it depends on the viewing angle?
Any clue what is causing it though?

[fused]

render mode? mlt/pt? bidir on/off?

[CTZn]

Intersecting meshes, or meshes below the allowed distance ? Too thin wall ?

You could compare a specular and a glossy materials using the same medium side by side with different Indigo versions... say, to spheres primitives, to elude geometric options.

[PureSpider]

render mode? mlt/pt? bidir on/off?

PT BiDir in all cases

Intersecting meshes, or meshes below the allowed distance ? Too thin wall ?

Nope, ray nudge distance is okay, even tried it with 10^-9; got black artifacts everywhere, problem remains the same.

€dit: Look at the floor of the glass... looks okay there in all cases; it only gets black when the viewing angle is more steep...

[CTZn]

Nope, ray nudge distance is okay, even tried it with 10^-9; got black artifacts everywhere, problem remains the same.

Well, we are not supposed to play with the ray nudge distance. Distance between surfaces should simply be above 0.2mm while using the standard r_n_d setting, like Ono says.

In all cases I think we should allow the doubt on the cause for that difference in tones, just because we ignore the technical reasons behind.

[PureSpider]

Just checked, the minimum wall thickness is 0.175 cm in all cases on the glass.

[CTZn]

The wall is allright then. Still, you didn't mention the floor/recipient distance. It could very well be above the minimal limits, if that matters. I'm just meaning to lead us to a maximized objectivity regarding the issue.

Edit: Extrapolating from what we know, if the distance for two objects when one at least uses a medium is below the minimum then perhaps the volume is considered open (I'm speculating). Opened volumes render darker iirc.

[PureSpider]

The wall is allright then. Still, you didn't mention the floor/recipient distance.

THAT was my first thought, too!
So I moved the glass up 1 cm to be sure and re-rendered - result is the same.

[CTZn]

okay