glass problems - turning black

[spadestick]

Hi, I'm always having problems rendering glass windows in max / viz. Sometimes I get it right and sometimes i don't... does anybody have any of the same problems too? it just seems very very touchy - you change a litte here and the whole thing becomes crazy.

FYI, all my glass is single sided, to save on file size and computer CPU / GPU cycles... otherwise it gets too crazy to navigate around complex buildings.
I'm refering to exterior renderings : will show an example when I get to the office.

eg. to avoid the problem I use a standard material (not vray) and apply a fake reflection map. It doesn't turn out nice or realistic but it solves the problem of black glass (not being able to see the inside of the building).

once I use a raytrace material then the problem starts. especially with the single sided material.

I tried using Vray material, and the moment I turn on the diffuse to completely black (as in the tutorial to make glass), and the refraction to almost white. things get very touchy...

anybody has any thought on this? I've tried forcing 2-sided and a mucked around with so many settings... but it doesn't work.

Currently I'm too lazy and tightly deadlined to change all the glass to 2-sided, but is that what I really have to do to solve this silly problem? what about water in swimming pools? how do you make sure that you can still "see" the bottom of the pool in the form of wavy pool tiles by a single face representing the body of water from sketchup?... it happens to go black too!

[ryo]

Actually, yes.
You HAVE to MODEL 2-sided glass in SU before importing to Max.
If you use Vray, there are tricks like you use but it's too random. If you don't use double-sided glass, the render engine thinks its thickness is infinite (unless the raytraced ray encounters another glass surface with normals facing towards the opposite side), and therefore gets black because of an infinite absorption.
If you use Maxwell, it's even worse: there's no trick.
The use of 2-sided materials in Max (via Mentalray, raytrace, or V-ray materials) doesn't always allow to avoid artefacts if you use single-sided glass.
Moreover, you need to check in SU before exporting that every visible face has normals facing towards you (no reversed face)... but you know this, aren't you? :D

[cacapis]

Thank you Ryo! I used to have the opposite problem back when I used Brazil, the glass did not show at all.

[spadestick]

thanks ryo, thanks for helping to clarify the issue...

now it's ... "oh man... some more hard work and crawling speeds ahead!"...

Artlantis doesn't have this problem though!... I've tried the demo and it works fine.

I've tried C4D advanced render and it's even better, you don't even have to reverse your faces if they are facing the wrong way!!

[ryo]

thanks ryo, thanks for helping to clarify the issue...

now it's ... "oh man... some more hard work and crawling speeds ahead!"...

Artlantis doesn't have this problem though!... I've tried the demo and it works fine.

I've tried C4D advanced render and it's even better, you don't even have to reverse your faces if they are facing the wrong way!!
I know... this reversed faces issue is a thing from the past... (3dstudio1.0 era).
But with correct modeling, you're sure your file will be compatible with a max of softs. :D I usually model in SU's monochrome mode, with white correct faces and red reversed faces, just to be sure of what I'm doing. reversing faces afterwards can be veeeeeeeery time consuming and boring, even with the help of the oneleftclick reversefaces tool...

[spadestick]

i normally assign the command to a single key on the keyboard, such as the letter "W" or something... and it is a thousand times easier than right-clicking or moving the mouse to click on a tool... approximately 10 times faster!

[cacapis]

I know... this reversed faces issue is a thing from the past... (3dstudio1.0 era).
3dstudio 4.1 (I mean the D.O.S. one) didn't have this problem!! :D:D
The first MAX was a huge step back until they could get the windows interface and functionality right.

[lef]

I always model the glass as a single surface in su ...and render in vray i never had serious problems .... :wondering
im in an internet point right now and unfortunately i can show you any examples ...
the glass turns in to black because one of these :
1 there is no enough light in the interior of the room so the wall or celling look dark grey or black and so do the glass .... try to make an invisible vray light in the room or something ...
2 in the vray s enviroment/refflections i suggest you to try to use an hdri because if you just left it black is obvious tha the glasses will reflect black ...
you could try to a light blue too ...
3 if you dont want to use a vray material , try a standard one , and in the reflection use the vray map ....
4 NEVER use raytraced materials with vray

thas all i can think for now , hope that i helped a bit .... must go ! see ya ! :)

[Stijn]

Sorry for bringing this old thread up, but it remains a recent problem. ;)

I managed to solve it by making the glass double. In attachment, the left is the single glass, the right is double glass. :rock on:

BUT, i have one problem. Some sides (ones that were mirrory when only single glass) now appear too grainy. The image is rendered with the "high" preset, so I don't think that it is the render quality. What might be the cause and sollution for this?

[Stijn]

2 in the vray s enviroment/refflections i suggest you to try to use an hdri because if you just left it black is obvious tha the glasses will reflect black ...
you could try to a light blue too ...

I tried the HDRI, and it makes a lot of difference. Very neat! :)

Meanwhile, my question about the grainyness still stands though... :wondering

[lef]

are you using 3d studio max ? or vray for sketchup ?
I think that your glass needs more reflections subdivs...
try this simple glass material for example ...
If you still have problem let me know ....

ps keep in mind that your glass won't be "realistic" unless you have a decent context to reflect ... 3d or 2d ...

[Stijn]

I'm using 3D Max. I am aware of the "context issue". But I like the result in previous post. I'm just somewhat bothered with the milky grain on some of the planes. I'll try the reflection subdivs thing and let you know.
I'll also try what you gave in the attachment. Always a pleasure to try different things.

It'll have to wait though, I'm doing a high Q for the moment.