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**Macker** · 24-10-2013, 08:06 AM

You don't need a falloff map in the reflection slot. Just tick the "fresnel reflections" box in the vray material, and set your reflection AND refraction to pure white. Then just use the fog to add a tint to your glass.

I have never, ever had a problem creating very realistic glass in vray.

**joconnell** · 24-10-2013, 08:15 AM

Vray and mental ray have no difference in the way they calculate glass. Glass itself is inherently boring so if you've got a white scene and pane of glass, it'll look rubbish. The thing that makes glass look good is having something interesting to reflect. Macker's got it totally right above in terms of material settings, the only thing some people d on large buildings is add in a very large and soft noise map at a low amount (like 1 percent) so that you get the slight bit of warp / wobble you see in real life but for a glass window in a house for example it's all about having something interesting for the glass to reflect. What you could try doing is put a large plane object facing your glass, turn it off to visibility and casting / receiving shadows and then map an image to it, so that the glass in your scene is facing something that it can reflect.

**Macker** · 24-10-2013, 08:19 AM

Agreed with the above. Also, I do (when realism really is required) set the reflection glossiness to 0.99 because I feel it breaks up any distant reflections, whilst keeping close ones super crisp and sharp.

**AJ Jefferies** · 24-10-2013, 08:25 AM

Just posting to agree with all of the above ^^

**Lupaz** · 24-10-2013, 08:35 AM

Macker: I think vray's fresnel behaves the same way as a falloff-fresnel map. I rather use the latter because I understand how to control it better.
I don't know how your glass looks like, and this is a very subjective interpretation I guess, but comparing renderings posted anywhere, I can tell looking at a rendering that the glass looks kind of fake. (very close to real, but not quite)
However, now that you suggest to use glossiness at 0.99: I tried that before, but I don't like the result. It looks like cheap glass or as if it had a transparent film on it. May be what we need is depth of field on the virtual side of the reflection, which you would have in real life. for now, prohibited for me.

joconnell: "...having something interesting for the glass". That's what I said on my first post. I already do that.
"Vray and mental ray have no difference in the way they calculate glass". Maybe, but mental ray comes with a pre-setted glass material. So even though both use raytracing for refraction-reflection, I believe they're both biased in everything else in the scene, and so you need to tweak things around, at least with vray. Am I wrong?

thanks.

**joconnell** · 24-10-2013, 08:52 AM

If mental ray has a glass material, it's just a black material with white reflections and white refractions (maybe a tiny bit off pure white in both) an ior of 1.5 and fresnel turned on - do a quick test with a box and render out the various render elements for both and see what the difference is. I'd say that http://www.peterguthrie.net/ and http://www.flickr.com/photos/bbb3viz/ just use the above for their clear glass.

Could you pop up a rendered image and we can talk about what you're unhappy with?

**Neilg** · 24-10-2013, 09:04 AM

It's all down to the scene. only when your glass is reflecting an entirely cg environment will it get close to looking right, and even then I never use glass straight from a render. I create masks to darken the edges, randomly shift the brightness of some panes, select the sky from the reflection etc.
Most of the time I render with no glass at all and do it as a separate fully reflective pass with a falloff in the extratex. if it doesnt look right then build it entirely in post, it's much quicker & gives way more control.

**Lupaz** · 24-10-2013, 09:50 AM

cubiclegangster: that's exactly my point. There must be a way to get a very nice result from 3d.

Joconnel:I did a random search on google images. These are some examples of what I'm talking about. the name or website of the person that did the rendering is on the watermark or the file-name for "copyright" purposes.

All of these are good renderings in my opinion. I know that I'm getting very detailed, but to me the glass usually looks flimsy, or too dark, not enough reflection, or too much reflection, or muddy, or like very thin, regardless the width given.
Why? I don't know.

even on the rendering by hramovsky, the last image, which is an amazing rendering, don't you think the glass looks too thin or just not real?
On the rendering by Aleso3D, very nice rendering indeed, look at the glass on the right side of the red building. Is it just that it's reflecting oddly big leaves?

And I purposely chose renderings that are done by talented, or seemingly knowledgeable artists. For the common artist it's much harder I'm sure.

Attached Files

**joconnell** · 24-10-2013, 09:55 AM

Pop up one of your renderings and lets talk about what you're not happy with - the glass shader is probably the simplest part of it!

**Lupaz** · 24-10-2013, 10:29 AM

joconnell: What's the difference? I'd say try to find a good amount of renderings with glass that looks like good quality real glass. It's hard to find and it's really not easy to do.
Again, I'm not blaming vray for this. I'm just interested in your opinions to see if there's actually something I'm missing.
Actually, I searched for maxwell renderings, also randomly, and they seem to have better looking glass. Why? Is it floating point on the environment?

**Pixelcon** · 24-10-2013, 04:04 PM

All but the last of those images posted are using a flat sky. of course they're going to look boring. The last image is reflecting not a whole lot and I don't think the glass is all that bad. The links posted previously show some amazing glass examples and they would have used the most basic of glass settings.

http://www.flickr.com/photos/bbb3viz/6001483502/
http://www.flickr.com/photos/bbb3viz/5462121065/

**squintnic** · 24-10-2013, 05:06 PM

its just a case of not being able to use max / vray properly IMO
there isn't a magic formula
this isnt science its a jpg

**Lupaz** · 25-10-2013, 07:10 AM

Squintnic: I respectfully disagree. It's not magic, but it is a formula. The formula for glass, among other components, is an algorithm that replicates refraction with IOR about 1.5 and fresnel reflection. Or something like that.

My question is:

Why on the following renderings, done in MAXWELL, my eye is foolled better than in renderings done in vray. (I'm referring only to the glass). Even in crappy renderings the glass seems to be surprisingly real.

http://www.cgarchitect.com/content/p...0534_large.jpg
http://www.ronenbekerman.com/forums/...e-frontday.jpg
http://www.itsartmag.com/features/it...l-render-5.jpg
http://www.digitaltools.ro/images/ma...o-exterior.jpg
http://www.ronenbekerman.com/forums/...morninglow.jpg
http://www.videocom.it/UserFiles/Image/maxwell_5.jpg

**Neilg** · 25-10-2013, 07:20 AM

They still look awful tbh, i've got no idea what you're seeing there that you cant make in vray.
The maths behind rendering is a very minor part of how something actually looks - stop expecting 'science' to do your job for you. There are so many reasons why glass can look good or bad, and it's not because the ior is wrong.

Glass can look good from a render, but it involves having a good scene, good lighting, & a very particular kind of setup. If you're not making fully cg environments and then going into them like a photographer, it will not look good and you will need to open photoshop. The only glass i've seen look good straight from a render is internal partitions, external glass always needs touching up. In any render - i've never seen mental ray or maxwell do it either (and it's not doing it in the examples you posted)

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