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I have use glass bsdf node on bottle object to make it looks like glass but i think there is mistake just like this. enter image description here

The part that i mark with colour paint,i dont know what is that, and why it end up like that,and it doesn't end there. My glass object's surface looks like fake,it doesn,t feel like a real glass,even though i have setup the nodes to make it looks like real glass.enter image description here

Also there is circle object behind the glass that i put in there to make support the background decoration, but i can't see it through the glass from front view.

So what i want to ask you guys :

1 Why there is weird reflection on glass bottle's surface?

2 How to make my bottle's surface looks like real glass and doesn't feel fake?

3 How to enable bottle glass's surface to be see through from front to behind so i can see the circle?

And here's my file https://pasteall.org/blend/669d37f0220243f3a2d1f5aeca942d4c

Thanks

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  • $\begingroup$ I guess your bottle has no wall thickness like a real bottle, so the glass material's refraction works as if this is a solid glass object. Try using a Solidify modifier. The strong refraction of a solid glass ball is responsible for those strange appearances there, I suppose. $\endgroup$ Commented Mar 18, 2022 at 13:09
  • $\begingroup$ @GordonBrinkmann i try using solidify modifier but the glass become blurry $\endgroup$ Commented Mar 19, 2022 at 1:15
  • $\begingroup$ Now that I've downloaded your file I see your glass actually has an inner and outer wall - of course my tip with the Solidify Modifier was only if this wasn't the case. This strange refraction looks as if you had no inner walls, but it seems that comes from the strange material setup. I've tried myself on an own answer, see below. By the way, the normals on your cork are flipped (but that doesn't cause any of the glass problems). $\endgroup$ Commented Mar 19, 2022 at 11:47

2 Answers 2

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//EDIT: I wasn't too happy that the light gets scattered in my material so there are no sharp shadows inside the bottle. In the other answer the black edge bothered me, which won't go away no matter how high I set the bounces. But I found the problem. So here at first the most simple setup which also renders a bit faster than the improved setup, which you will find further below.

Simple Setup: I downloaded your file and made the material setup a little bit easier... a quite good glass material is actually the Glass BSDF. To keep it from looking too dark you have to do two things:

  1. Make it completely white with R/G/B = 1/1/1.
  2. Increase the bounces of not only Transmission, but also Glossy (and then of course the Max bounces or Total in newer versions, because they limit them overall).

So this is my material setup (this is from my Blender 3.1 version, but the render below I did with 2.79):

glass material

And this is the render result with the following bounces settings, Max: 32, Diffuse: 4, Glossy: 32, Transmission: 32, Volume: 0.

glass bottle render

I think this looks quite okay. You'll never get rid of some of those dark areas, since there are objects with shadows which also get reflected and refracted. The crucial thing is, many people just crank up the Transmission bounces because they think, darkness in transmissive things only comes from too few bounces there. But since the glass is also glossy, those bounces play a role that's not to be underestimated.

Improved Setup: The solution to get sharper shadows inside the bottle from outside lights is a setup which is close to the answer from @mqbakamqbaka - the dark edge which bothers me is caused by the Is Reflection Ray light path. To get a better result, use Diffuse Depth instead:

new glass material

And this is the new result, I still used the Glass BSDF, you can use a Principled BSDF - that doesn't make much of difference. Only that the Principled BSDF gives a slightly darker result, but it doesn't look more or less realistic than the Glass BSDF. The only thing I experienced (on my PC) is that in 2.79 the Principled BSDF renders faster than the Glass BSDF while in 3.1.0 it is the other way round.

new glass render

Another thing: if this result seems to be too bright inside the bottle (since no real glass lets 100% of the light pass through), you can always place a Multiply node after the Maximum node to multiply the result by some value lower than 1, which works like mixing between the simple glass material if you multiply by 0 and completely improved material at 1.

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  • $\begingroup$ You are always reliable, I compared those 2 image for a long time to see the difference~But I think what he asked is the round dots on the bottle.It's from reflection ray,as his node shows,wherever there is reflection ray,there should be totally white, no matter how many times the ray has bounced.So,even the last bounce will also show the same as the first bounce, that's make the round dots. The less the bounce is,the more star alike the shape is. $\endgroup$
    – NatureK
    Commented Mar 19, 2022 at 12:43
  • $\begingroup$ Well, I just went for the three numbered questions he asked... #1, the weird reflections he marked in the screenshot come from the material setup, but this problem vanishes why my take on #2 and #3: make it look like real glass and see through, so that you can see the circle behind. I think my version looks quite okay. I didn't bother to investigate deeper how those wrong reflections are created since you don't have them with a proper material. $\endgroup$ Commented Mar 19, 2022 at 13:06
  • $\begingroup$ By the way, there is one thing that bothers me with my simple glass material: the light from the outside gets scattered a lot more so that e.g. the green grass leaf doesn't throw a sharp shadow on the mushroom, but well... at least it is an easy material setup. $\endgroup$ Commented Mar 19, 2022 at 13:17
  • $\begingroup$ Well, as you all predicted , i can't get rid the black edge on my glass even though i have followed Gordon's instruction to change the Light Paths's setting $\endgroup$ Commented Mar 19, 2022 at 13:48
  • $\begingroup$ Thank you for all your suggestion, it helped me to understand what needs to be done and what cannot be changed to make perfect glass surface $\endgroup$ Commented Mar 19, 2022 at 13:50
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The problem somehow comes from your node setup, if you use the glass BSDF directly, the render looks normal :

enter image description here

Also, if you are using 2.79, you can use the principled BSDF shader and turn Transmission to 1 and Roughness to 0 to make a glass material, it will give a more realistic glass (I'm not sure that's what you are going for tho) :

enter image description here enter image description here

Only problem left is that the objects inside the glass are darker. This can be solved by a workaround from this answer :

enter image description here

It's a similar setup as the one you originally used but instead of Refraction Ray and Ray Depth we use Shadow Ray and Refraction Ray. This gives a better result :

enter image description here

If you still think the glass is too dark, it may be caused by this :

enter image description here

The default color in Glass BSDF and Principled BSDF is not pure white by default but some kind of light grey (which is, obviously, darker than white), if you drag that slider all the way up, you get that :

enter image description here

The black thing you see on the edge of the bottle is due to the fact that I reduced the transmission bounces to render a bit faster, if you leave them at the default value, you should not have that.

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  • $\begingroup$ learn much from your detailed answer and links, thank you. $\endgroup$
    – NatureK
    Commented Mar 18, 2022 at 14:04
  • $\begingroup$ I have tried your suggestion and it worked, except for black thing on bottle's edge. I had setting in light path on render panel like this : max. bounce : 12, diffuse : 4, glossy : 4, transmission : 12, volume : 0. When i change the transmission value to 4, the black thing doesn't vanish, also when i tried to change the value to 0, it become black. I'm kinda wondering if this setting is the one you are talking about or is it somewhere else $\endgroup$ Commented Mar 19, 2022 at 1:29
  • $\begingroup$ sorry for my long sentence( if you find it difficult to read), cause i want to know what is the problem for removing black thing on bottle's edge $\endgroup$ Commented Mar 19, 2022 at 1:31
  • $\begingroup$ I don't know why it's always so complicated to get a good glass result... I simply used the Glass BSDF, see my answer below. $\endgroup$ Commented Mar 19, 2022 at 12:09
  • $\begingroup$ Yep, sorry for the misdirection, for my 2 firsts screenshots I left the max bounces at default and I lowered them on the last 2 where the dark edge appeared so I thought they were caused by the low value of the light bounces, I think @GordonBrinkmann explained the issue better in his answer. $\endgroup$ Commented Mar 21, 2022 at 5:40

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