Rendering Clear Glass

[jsimanyi]

I've had very limited luck with the built-in version of Povray for clear glass. I'd like something like this done in Povray:



Or perhaps http://forum.sketchup.com/attachment...1&d=1152040773 gives a simpler example, although it's a different rendering engine.

I realize that Chief's version is dummed down quite a bit, but...could anyone (Dean???) give some tips in modelling or adjustments that might work better? I've tried making faces double-sided, but I usually build double-walled containers instead. Single-sided faces really don't work. I've tried all the sliders on advanced, but it never seems to look quite like clear glass. Colored glass works much better, but clear glass never really gets that edge definition.

In real glass, looking at a tangent edge provides a visible color shift (darker or lighter, depending on light source) that defines the shape. I've never even come close to that yet!

It may not be possible, but I was hoping someone might have an answer. I've even tried countering the flash/reflection of the glass created through increasing reflection by starting with a black material (didn't work, either).

Hoping it can be done,

John S.

[Chiefer]

You may download a stand alone Pov-Ray v.3.5 (freeware) to use photons in your renderings. Attached is a photons scene template.

[lbuttery]

Pov-Ray v.3.5

The newest version is 3.6

Lew

[Chiefer]

you're right, it's v3.6...

[Night8917]

Hi John.

I agree with you, glas is very hard to Raytrace in Chief.

After MANY hours of testing different settings I got this.



Sorry the picture is so small, I will make a bigger one later today.

There is one setting that should have a bigger spread and that is Shininess. You should be able to set the Shininess higher, so that the Specular point can be smaller. Maybe there is a way to go around this but I don't have time to test it right now.


Have a great week.

[cgirerd]

That's great looking glass, Lars! I know I sure have never gotten a glass to look that good. If I have close-up views, I try to avoid having glasses on the table because they usually look so fake. I'd love to know your settings for that if you're willing to share them. It's good to know that Chief raytrace can actually produce something like that.

Christina

[Larry Kumpost]

John:

I would think that since, in the real world, the glass has volume and we are rendering surfaces, getting an exact match would be a problem for the type of view you show in the image.

Just curious, are you trying to render a close-up view of glass objects or windows in a building? I just realized that this could be taken as a comment and it is not intended that way. What is your objective?

Are you using a color for the glass materials? I have used black, gray, dark browns, blues and even greens depending on what I was trying to achieve.

[jsimanyi]

Larry -

First of all, that first image in the thread is a POVRay rendering. I understand that it may be difficult, but it sure looks enticing.

As per the reason for this thread, I just did a coffee grinder w/glass hopper in another thread, and I couldn't get the look I was after. Heck, I can hand draw glass better than the images I'm getting through the GUI-easy version of POV! Colored glass allows you to define a shape pretty well, but it still isn't quite right:

http://www.chieftalk.com/attachment....7&d=1143360761

Expand it to full size, and I think you'll agree it looks far more believable than any clear glass done through the Chief interface. I still don't entirely understand the lobed look inside the bottle (3D math...have to ponder more...). The bottle was done as a two-walled container with a flat surface for the liquid. Likewise, the hopper on the grinder was also done as two-walled, but it has no glass "feel" to it:

http://www.chieftalk.com/attachment....3&d=1154961804

I just want a more accurate look for clear glass, as the rest of the renderings look pretty good. Waaaay back before built-in POV was available, I started (and JUST started) playing with POV. I think it might be time to have another look at it.

Thanks everyone for the input,

John S.

[Larry Kumpost]

First of all, that first image in the thread is a POVRay rendering. I understand that it may be difficult, but it sure looks enticing.

I under stood that is what you said...but still hard to believe. Doesn't look like something that can be done on the average home computer. Or even the average CAD system. Did they give any detail on how it was done and what was used? Can you provide a link to where the image is posted. I would like to read what it says.

I just want a more accurate look for clear glass, as the rest of the renderings look pretty good. Waaaay back before built-in POV was available, I started (and JUST started) playing with POV. I think it might be time to have another look at it.

The image Anders posted looks pretty good. Looking forward to the larger image he said he would post. I would also like to see his material settings.

[pktraylor]

Been watching this thread closely because I use a lot glass in my designs. After looking at the post of Lars, I am ashamed to post my best.

Like Christina and Larry I to would like to see a larger picture and a post of the material settings. I have a feeling that there are several hundred posters that would also like to see them.


Thanks Lars.


Paul

[jsimanyi]

Larry -

http://www.povray.org/

Scroll down to the Wikipedia picture of the day on the left. He's obviously a POV guru, but I was just posting it as a good visual example. If Anders/Lars was done through Chief's interface (I don't think it was, but I'm hoping as well), I'd much rather avoid going to POVRay with photons. He's pretty good at tweaking settings.

John S.

P.S. Woodcrest w/SMP quad core will be my next build in about 6-8 months. This should make raytracing a much less patient proposition if I go to newer POV.

[Larry Kumpost]

John:

The way I read it he did do that in Chief

I agree with you, glas is very hard to Raytrace in Chief.

After MANY hours of testing different settings I got this.

At least that is what it sounds like to me. I have never been all that concerned about rendering a glass but I think I can get fairly close. I spent hours playing with glass material settings at one point because some of the "Out of the Box" settings in Chief were so bad. I'll take a look.

One other thing. Can you post the settings you used? I might be able to see what is wrong.

[jsimanyi]

http://www.chieftalk.com/showthread.php?t=19942&page=3

There's a couple of screen captures a bit down the page (plus the symbol, if you want to compare apples-to-apples). I messed with it some more this morning before heading off for real work, and it seems as if I'm fighting with reducing a tendency to appear opaque and bright vs. getting enough reflection. I'm definitely open to suggestions.

Thanks,

John S.

[Dean]

In real glass, looking at a tangent edge provides a visible color shift (darker or lighter, depending on light source) that defines the shape. I've never even come close to that yet!

To get 'REAL' one must use constructive solid geometry native to POV.

My avatar is an example of this. starting with a geometric shape or perhap a surface of revolution and subtracting what isn't there to achieve a final solid like a mug or a wine glass. next that solid gets an index of refraction as does any liquid inside the glass. then through the use of photon mapping, faked caustics. diffraction and dispersion calculations, POV can make the "glass" look realistic.

If you just want to change the window glass, it is a bit easier. Since window glass is essentially flat, there is no need for refraction caustics and photon mapping.

In your PovRay folder, ( the one in your Chief 10 directory ), there is a folder called 'include'

In this folder is a file called glass_old.inc

find the entry for T_Glass1


#declare T_Glass1 =
texture {
pigment { color rgbft<.95, .95, .95, 1,.5> }
finish { F_Glass1 }
}


#declare F_Glass1 =
finish {
specular 1
roughness 0.001
ambient 0
diffuse 0
reflection { 0.005, 0.1 }
}



these are the setting I like to use

read the POV help to see what those settings mean

Dean

[Night8917]

HI Guys and girls.

Sorry you have to wait so long, I'm doing a BIG Raytrace at the moment and I'm waiting for it to finish so that I can make the glas Raytrace, it has taken 14 hours so far and it's a few hours left to finish.

I will put it to Raytrace as soon as the big one is done.

I will also post the settings for the glas.


Take care