Black arc appearing in glass

V-Ray for 3ds Max V-Ray for 3ds Max :: General
1

Hi,

Does anyone know what could be causing a black arc to appear in the glass of the rendering below?

http://www.msnusers.com/WDGDigitalMedia/shoebox.msnw?action=ShowPhoto&PhotoID=2

Thanks,
Dalia

2

It could be that you have your sky set to Texture Coordinates instead of Environment.

--Jon

3

Could be your cutoff threshold:

http://vray.info/entry.asp?entryID=106

4

We are using a skydome with a 360 degree sky bitmap. However, even with the sky dome turned off the arc still apears in the glass for some reason. Any thoughts?

Thanks for your help.

Dalia

5

Did you try lowering the cutoff threshold?

6

I ran in this problem before, once I managed to make it look tweaking the normals, the second time, I modelleg my glass correctly, instead of a plane it became a box with a 3mm thickness.

7

Hi,
Our glass is a single plane. Should we model it with a single thickness from now?

Thanks,
Dalia

8

Hi, I tried lowering the cutoff threshold to .001 but it is still rendering the black arc. Any other ideas?

Thanks,
Dalia

9

EGZ.

Love the new avatar :lol:

Tony

10

try this:

convert the plane to editable Poly, select all polys and clear the f***ing smoothing groups. give it a standard mat with opacity 20 and fallof’d vraymap as reflaction.

i had the black arcs in the past and this helped me. :smile: If you give your glass a thickness you will have to fight with the IOR. Planes are good enough.

11

Thanks zloner. Your suggestion worked.

Dalia

12

I suggest single sided objects aren’t good enough, use a real world thickness and appropriate IOR. Using single sided objects is a bit of a no-no when using a raytrace/GI engine in my opinion.

13

i agree. heck i model every glass windows with boxes very thin. then i apply egz glass to it (im too lazy to setup glass in vray material hehe)

14

ok elfi, have fun with no alphas. The egz glass got non.

And rhino, for what do you need an IOR that is different from a plane. Why wasting Polys. My window-glass has 1 poly for 100 windows, your tec. means that you have 600 Polys for 100 windows. Would not work for me, scenes i build for clients have at least 1,5 Mio Polys.

greetz

15

use the solidify plugin if you only have single plane windows. Regardless of orientation they extrude to their normals. Its quick and easy.

If that doesnt fix it, check your cutoff threshold like EGZ suggested…

Arkitec

16

Because real glass is a solid mass, well it’s actually considered a liquid if my high school science class was correct and it has an IOR, bad computer renderings have single sided planes with tons of reflection and no refraction. :lol: joking, no seriously I remember when I would wait 3 days for an image to render just so I could have refracting glass, now it’s a standard effect. If you are really worried about faces just make the one large plane into a box, I’m sure Vray can handle the extra 5 faces, splurge a little, so that’s one less rpc object you can put in the scene, well would that be so bad? hell if I put enough windows in my scene I could totally do away with RPC objects, then I would be living in some sort of arch viz utopia.
Personal preference aside, there are some valid reasons for not using single sided objects, in my experience they cause havoc in a raytrace environment, this was certainly the case with FR and I have experienced similar anomalies with Vray (GI problems, artifacts, crashes) I consider it good practice to do away with bad faces/open objects. Vray is certainly robust enough to render refraction in glass, the speed tradeoff is minor, working with refraction just takes a bit of preparation and planning but is worth the extra effort for the resulting quality. It’s up to you if you want to use refraction but I certainly suggest using two sided objects to avoid problems and insure max compatibility with other and future raytrace engines.

17

ok elfi, have fun with no alphas. The egz glass got non.

Uhm.. yes it does. :roll: