did you know that if you turn off raytracing on the reflective objects that it will render without IDL and with reflections?

as we all know glass doesnt cast shadows and there are no soft shadows from IDL. there is no occlusion.

using glass without shadows is not a problem. right? since we just turn of shadows.

this is an example where IDL is turned on. i am using bagginsbill's ENVsphere. as you see there are soft shadows. but its glass and there shouldnt be.

and voila. i turned of raytracing on the objects. as you can see the reflections is still there but it is ignoring the lighting from IDL.

i dont know if this was a mistake or if this is a bug. but this should not be fixed. AGAIN.......................dont change this. dont change this.

where can we use this?
-glasses
-windows(house,car,....)
-.....

i have the glass and the frame as seperate objects.

Glass does cast shadows in reality. I'm looking at a glass on a table across the room right now and it's casting a shadow.

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Weapons of choice:

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Quote - Glass does cast shadows in reality. I'm looking at a glass on a table across the room right now and it's casting a shadow.

but its not a full shadow. its maybe 5 %

the problem is that in poser you have a full shadov or no shadow. and IMO its better to have glass without shadows than with shadows.

It's not exactly a bug, it's a weak part of Poser's renderer design. In the big dog renderers, you can selectively control whether objects are included in GI, reflection (and what depth of bounces for each of those, separately) and whether THIS object is illuminated by THAT light. Also, transparency and alpha are treated completely separately in other applications, whereas Poser treats them the same (which is why no colored shadows through transparent objects). The fact that Poser Indirect Lighting occlusion shadows don't handle transparency well is another big flaw. Pretty sure none of these things can really be worked around at all in Poser.

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nodding at Pjz99 Yes, known limitations of our render engine at the present time. I say though, on rendering glass, it's far better to render WITH a shadow, than with none at all.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

Quote - nodding at Pjz99 Yes, known limitations of our render engine at the present time. I say though, on rendering glass, it's far better to render WITH a shadow, than with none at all.

can you explain why and show examples where it looks good?

imho, you just did. the versions with no shadows looked much more unreal than those with. though that might be fixed by compositing a faux glass version with a real refracting version. you don't even need a real refracting version for glass that shouldn't visibly refract (windows and such).

pjz99 - actually, iirc, that's not why there's no colored shadows. there's no colored shadows because something internal hasn't been turned on. bagginsbill mentioned recently in some thread, i think.

Quote - imho, you just did. the versions with no shadows looked much more unreal than those with. though that might be fixed by compositing a faux glass version with a real refracting version. you don't even need a real refracting version for glass that shouldn't visibly refract (windows and such).

pjz99 - actually, iirc, that's not why there's no colored shadows. there's no colored shadows because something internal hasn't been turned on. bagginsbill mentioned recently in some thread, i think.

the first pics are just examples. they were not meant to look real.

M4 with glasses on. the one where hes eyes are dark is more real ?

WTF

the one with no shadow at all looks about as unreal, imho. try that one with faux glass, and see what you get. as long as IBL respects transparency, that should give a much more realistic shadow.

Quote - the first pics are just examples. they were not meant to look real.

M4 with glasses on. the one where hes eyes are dark is more real ?

No I agree with you, the dark one looks pretty bad and the no shadows one looks better, but this is only because in that particular scene the lighting supports it. In a scene with more defined shadows, the no shadow one would look like the guy's eyes were glowing. Basically we need this stuff to work like expected and the fakes we use only give bad results.

it may be a question of which glass shader is used, and what IDL settings. idl causes objects to cast soft shadows, which is what AO is trying to fake. glass cylinders and spheres cast shadows, e.g. when held over a table in an office. there appear to be alotta things wrong with the poser 8 glass shaders (see att img).

no, it's not a question of the glass shader. because there are no caustics in Poser, anything that has no transparency is treated like a solid object. this is why bagginsbill's window glass shader uses transparency with reflection and fresnel, not refraction. using a shader built like this will give you shadows that are pretty decent (though not the light patterns from actual refracted light).

i haven't checked to make sure transparency works properly with AO, and i don't have P8 to check whether IDL-based AO works properly with transparency. if it does, then faux glass will give the proper shadows and occlusion, even if it doesn't give proper refraction. then you can do the render in 2 passes. for instance, a first base render with the area renders for your refracting objects.

I saw a glass shader thread by bill at rdna, but it appeared to be for poser 6. if ice-boy or somebody else can post whatever glass shader they're using, it would be instructive. we get shadows under glass in carrara (see above), but the carrara shader looks like a bad poser shader as well - sum of the active channels is greater than 1.

it's not the channels. it doesn't matter what you do to the shader. nothing makes something transparent in Poser except transparency. to actually calculate what happens to light when there's refraction would require caustics, which Poser does not support.

here are a water, glass, and sapphire material using:

CoE
bagginsbill's TrueFresnel equation
sRGB correction/linear workflow
a refraction fix for P7-
3 raytrace bounces
AO
ior values i found on Wikipedia

note the shadows and AO. they're the same for all 3 spheres (it's all crappy due to the very high shading rate). this isn't using IDL because it's just P7, but i doubt the AO calculation is hugely different when it's a part of IDL.

i'm not trying to say that my materials are perfect, but i can tell you that addressing anything but the diffuse properties of the materials of the objects in question will have absolutely no effect on IDL or AO in Poser. you can do stuff like make them not cast shadows or make them invisible to raytracing, but that's object properties, not material ones.

Quote -
I saw a glass shader thread by bill at rdna, but it appeared to be for poser 6. if ice-boy or somebody
else can post whatever glass shader they're using, it would be instructive. we get shadows under
glass in carrara (see above), but the carrara shader looks like a bad poser shader as well - sum of
the active channels is greater than 1.

from BB

o.k., thx fr img, ice. in bill's shader (above img), most channels are zero, including transparency.
he uses fresnel equation (sum of channels <= 0) and a method of fresnel effect via edge-blend.
refl. value always <= 1, and refr. value <= (1 - refl.) <= 1. hence the question might be why there's
a shadow from such a shader. I reckon it's because the refractive and reflective fx keep some
of the light from reaching the ground. the part about reflections with no raytracing and no IDL is
not clear, as d3d's script may still be in effect after poser render screen and/or object properties
are changed.

it's true that in poser 4 the only way to make something transparent was to use the transparency
thing in the old materials screen, but look around and try to find something that has zero thickness
and is non-refractive. the answer is easy: nothing. a vacuum might have no refraction nor
scattering in intergalactic space, and we can see thru it because it seems to be transparent,
but that is the definition of "nothing", if we exclude any consideration of dark matter, which
ain't accounted for in any human rendering engine.

I spent most of yesterday using every glass shader in my materials library to look like glass under IDL and only one looked right. I did not realize this was a problem with IDL. I keep hoping that BB will come and visit this thread and tackle the issue. And yes, I started with his lovely orb shaders and those didn't look glass-like under IDL. Sad, because I was going to do an image that requires a wine glass as one of the main elements of the render.

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Weapons of choice:

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Miss Nancy - in bagginsbill's shader and that image the sphere casts a shadow because it's not transparent and it's not set to not cast shadows or be invisible to raytracing. in all versions of Poser refraction does not actually allow light to go through the object. to handle that, it would have to have caustics. it doesn't. you're confusing what the surface of the object does and what that material does to other surfaces.

this is why bagginsbill made his eye prop. it needs a separate lens group so that it (and not the rest of the eye) can have shadows turned off. if you look up his discussions on the topic, you'll see that this is required to stop the iris from being shaded in Poser. it is not required in any renderer that doesn't support caustics. the same way reflections aren't included in IDL calculations, refraction is not included in shadows, AO, or IDL.

if you look up his information on glass, you'll also see his script for glass panes using his TrueFresnel equations (he hasn't been using that EdgeBlend trick in a while), reflection and transparency. and why he suggests using that rather than refraction for glass that has negligible net refraction. he's written about the issue and the transparent window glass for years.

from the BBEye page (http://sites.google.com/site/bagginsbill/free-stuff/bbeye)
"The eye is in two parts. The cover part must not have shadows enabled. It requires ray-tracing as it uses reflection and refraction."

that said, i discovered this before reading his posts about it when i tried to light a room through glass windows and ended up with no directional light coming through. i asked him about it, and he explained.

as for the discussion of refraction and dark matter, you're just not making a lot of sense. it has nothing to do with thickness (which is actually a problem with Poser refraction). it's simply a limitation of Poser's renderer.

we could fix the eyes in poser.

we would have to make an extra group and bone to the OBj. and then it would be seperate where we would turn of shadows.

as i mentioned, bagginsbill has already done this with his eye prop. odf and lesbentley have made attempts to incorporate it into Antonia by default, but the extra group was giving them some problems.

I got nothing to add - kobaltkween is covering the matter perfectly.

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o.k., then all I had was the edge-blend version, as in the one ice-boy posted above. it produces a
mirror ball effect with those settings.
is the bbeye shader the right glass shader to use with panes of glass and crystal balls?
I'm reluctant to turn off shadows for those, altho I can see why we would turn off shadows for
a cornea. I recall the cornea was done with transparency in poser 4, which meant it had to
be deleted or modified somehow when doing toons with poser 4.
anyway, I'd like to see an optically correct render of the crystal ball and glass sheet in poser.
the question of turning off shadows might only apply to a directional lite and not a diffuse envsphere
with an hdri applied to it.

o.k., I think I finally got it (with thanx to kobalt). we get fake-looking dark areas under glass objects in poser (idl, hdri, upper img) because there's no caustics (gi, hdri, lower img). they aren't real shadows, hence it looks the same whether or not "cast shadows" is checked, unless using directional lites.

That glass looks great! What shader is that???

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

it's bill's old p6 glass shader (not the new bbeyes shader). still no caustics, however :crying:

I couldn't figure out how to use the bbeyes as a glass shader. I'll give the shader you pictured a shot.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

I'm doing some experimenting with the mathematics of architectural glass. I'm building up a pretty good highly customizable glass material, that's really easy to use.

There is some additional math related to thin glass versus thick glass. Pretty interesting stuff. But we still have no caustics, and if you're using IDL, you must make the glass invisible to raytracing. As Miss Nancy has verified, Poser IDL does not "see through" any sort of glass, whether based on refraction or based on transparency.

Here is my first demo - plain simple window glass, but thin! Thin glass gets multiple internal reflections, which amplify the reflections.

(click for full size)

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Tinted with a neutral gray. This doesn't change the reflections, but does change the refractions. The increased contrast gives the impression that the reflections are stronger - they are not.

Note: Without GC it looks nothing like this. GC is mandatory if you want realism.

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Thin film metallic coatings are used in architectural glass to increase the reflectivity (decreasing the air-conditioning needs due to solar heating). They are often interesting colors as well, to enhance the appearance of buildings.

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"Solar glass" combines tinting with thin-film coatings.

Here I'm using a green tint, and a blue thin-film metallic coating.

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Slight thin-film, green tint *and* green diffuse, as if some microscopic opaque particles are embedded in the glass.

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Looking great!

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

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this looks great.

i say f.... caustics in Poser .i rather have subsurface scattering and fake looking glass.

lets just make it invisible to raytracing and lets enjoy the reflections.

SM SSS......................give me SSS

Yes, I'm not worried about caustics at the moment. I'd rather SM let BB dig into the Node system itself and do some corrections.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

i think the blinn node needs to be fixed. all the nodes made when Poser didnt have gamma correction. IMO the blinn node doesnt work perfect with GC.

i think we need a better specular node. and i think we need a cloth node. something for clothing. something that has sheen .
i want to render out a simple sweater or t-shirt. but with the poser nodes it doesnt look good compared to the skin.

Quote - ...Poser IDL does not "see through" any sort of glass, whether based on refraction or based on transparency.

wow. that's a big problem right there. you're saying IDL doesn't respect transparency, which has lots of implications outside of glass. imho, it's a bigger deal that this messes up every fabric that's partially transparent. and explains why that P4 vs. P8 render had so much darker stockings in with IDL in P8 than in P4. i noticed and wondered about it, but didn't think too much about it.

i remember a big selling point for DS's pwSurface was AO that respected transparency, but i just hoped several versions of Poser would have addressed that by now. i guess not.

You mentioned pwSurface AO respects transparency.

Poser AO also respects transparency. But, IDL does not. I don't know why.

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Here is the first test I did. The glass is 100% transparent and has no reflections or anything else - effectively it is invisible.

This rendered with invisible to ray tracing.

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But when I make it visible to raytracing, secondary light does not reach inside the box.

(Rendering with no lights here - just the EnvSphere)

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Here I have my "sun" infinite light enabled. This primary light *does* reach inside, and once there it bounces around. But I'm only getting half the secondary lighting. The contribution of the sky is missing.

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you know what is funny?

it ignores the transparency. but at the same time the rendertime is longer.

YES!

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Quote - Here is the first test I did. The glass is 100% transparent and has no reflections or anything else - effectively it is invisible.

This is because Poser treats alpha and transparency as the same thing, which is a shame. Very big downside in itself, along with the problem of transparent objects occluding GI light anyway (that's not even a design "feature", that's just bad).

My Freebies

I have to say that a great part of my enjoyment of Poser is due to my participation in this forum. When somebody asks a question or raises an interesting point, it provides the impetus for me to investigate the physical properties of the world we live in. Figuring things out and deeply understanding them is incredibly satisfying to me. I thought I understood glass pretty well before, but I was wrong. I'm learning some fascinating things. My glass shader is now around 70 nodes as a result.

What I've learned over the past couple days is going to make an excellent chapter in my shader book. But it's very complicated.

The cool thing is that using the shader isn't complicated at all, despite how hard it is to build it.

Anyways... I thought I'd share a couple more demonstrations.

#1

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#2

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Oooooo, and these are with IDL or are the items turned of to raytrace?

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

what i found interesting is that the glass shader still exhibits reflection and refraction by a
posersurface, even though "visible in raytracing" is unchecked for the glass object. in addition,
my initial attempt at a render of the glass-fronted box with IDL IC at 100 (GIMaxError=0)
appears to allow lite from the hdri on the envsphere into the box (thru the glass front) but it's
the slowest render since GI/poser 7, hence I hadda terminate.

Looks great. What was missing before?

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.

Quote - what i found interesting is that the glass shader still exhibits reflection and refraction by a
posersurface, even though "visible in raytracing" is unchecked for the glass object. in addition,
my initial attempt at a render of the glass-fronted box with IDL IC at 100 (GIMaxError=0)
appears to allow lite from the hdri on the envsphere into the box (thru the glass front) but it's
the slowest render since GI/poser 7, hence I hadda terminate.

this is great. and it is good for us.

it turns out that it's not necessary to use IDL IC=100. using the simple glass refractive/reflective
shader with approx. 0.01 diffuse, I'm seeing the hdri lite go into the glass-front box and it
appears to be bouncing around. a lite meter inside the box appears to detect about 50% of
the illumination seen by a lite meter outside the box, which might be expected in reality
(darker inside than outside during the day). I can't tell if the glass is cutting down on diffuse rays
from the hdri as they enter the box. will try to post render later.

when I look into a room with a sliding glass door half open, I don't see this much vertical deflection, even tho glass IOR is 1.5 or greater, not 1.2. it appears that the refractive glass is preventing some lite from getting into the box, and is also preventing it from bouncing back out. presence of small amt. of diffuse has no effect AFAICT.

Quote -
when I look into a room with a sliding glass door half open, I don't see this much vertical deflection,
even tho glass IOR is 1.5 or greater, not 1.2. it appears that the refractive glass is preventing some
lite from getting into the box, and is also preventing it from bouncing back out. presence of small
amt. of diffuse has no effect AFAICT.

I've been meaning to address this with a diagram but I've been kind of busy.

The thing about thin glass is this: it has the same refraction as any glass - it is glass. But it is thin. When light enters the glass, it bends towards the normal. Then it travels a very short distance through the glass and reaches the other side. From there, the reverse refraction happens, bending the light back to the original direction it had when it entered in the first place. The result is a photon passing though thin glass does not change direction at all. It simply hops off its original path a tiny bit, but its ultimate path is parallel to its oriignal path. This is completely different from thick or curved glass.

Poser's Refract node does not understand that it should be using the specified IOR when passing from outside to inside, and then the inverse IOR when passing from inside to outside. This is why it looks wrong. It is doing a double entry refraction, instead of a proper entry/exit refraction.

The usual hack to deal with this when using a single layer mesh is to simply set the IOR to a really small value, like 1.05.

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Here's the diagram.

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Note that if the two sides of the glass at entry and exit are not exactly parallel, then the heading does change.

A curved glass airplane canopy does change the heading a little bit because it isn't flat. The entry point and exit point are not parallel.

Also, even if a glass pane is flat, there are tiny imperfections or undulations in the surface that make it not perfectly flat, so there is some distortion possible. But it is usually so neglible as not easily noticed through casual observation. For the most part, looking through a modern window produces an undistorted view.

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BB, did you ever post the shader you were using in the examples earlier in the thread?

Not yet but I will soon.

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I hope this thread has not been forgotten! I have a planned poser project where a wine glass is the focal point of the image and I'd like to do it under IDL. I don't want to have to revert back to Poser Pro.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

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But I dont' have any new solution for IDL. I posted last week - nothing you do in Poser 8 or Poser Pro 2010 makes this work right.

SM needs to fix the IDL. It must honor transparency.

Second, SM needs to let us specify transmission (letting light through) even if we're using refraction.

Meanwhile, I already posted a wine glass weeks ago, with shader that does the glass and the wine. Did you miss it?

The, now banned, DP Hoadley was using it.

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Ah, yes, I have that prop. I can hope that maybe SM will take consideration on the problems you've brought up when it comes to transparency and refraction. I can but hope.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

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Forum: Poser - OFFICIAL

Subject: Glass and Indirect Lighting