Mental Ray - Shaders

[MasterZap]

hi there, i have problem when rendering through glass material - i have simple scene where is camera placed before glass plate and behind them are simple object and skydome

the problem is that the skydome uses mr raytype switcher for sky - the method that Jeff Patton has on his blog ( Skydomes in 3dsmax with mental ray (and FG) ), and this skydome object is not rendered, i tried to put this raytype material into mr connection shaders - into volume, or envirnoment, but nothing changed

The reason the object is not rendered is because you have set the OBJECTS “visible to reflection/refraction” to OFF.

Also you have something strange w. your glass material. F9r a window, you should use the “Glass” material in your scene (the shader ball to the left of the shader ball w. checkers on it in the material editor).

What I wonder, though, what you are trying to acheive, in principle?

Firstly, to rayswitch between “what you see” and “what bouncing rays see”, you should use the “Environmet/Background Switcher”

Secondly, I wonder what your end goal is, because I don’t really see the reason for the skydome at all. If you want to light by something other than your environment map, well, then simply use a different environment map - the lighting comes from the “mr Sky” skylight.

The environment map (in Environment dialog) is used for reflections and to “see”.

If you really want to split out “reflections” and “what you see”, then use “Environment/Background Switcher”, that’s what it’s for. Do NOT use the general rayswitcher or the “advanced” rayswitcher for this.

/Z

[MasterZap]

I have seen this effect in real life photography too,

http://flickr.com/photos/scoobay/1515241906/

Exactly - it is the correct render!

The reason it looks like this is your white environment, which reflects on the edges of the glass which makes you not actually see the edge at all. This isn’t the “water going outside the outer edge”, it is the water appear to go outside the inner edge - which is something you will see in ALL photos of a glass with liquid.

It still doesn’t go outside the outer edge.

The reason it looks odd is because you don’t actually see the outside edge, in this particular lighting scenario (white on white…)

Can someone help me out with this, I am going nuts over this.

In principle, what is there to help, since it’s the correct render?

If you want it to look “less odd”, put something in that makes the glass’ outer edge visible. Like a slight color tint to the glass (i.e. not make the glass transmittance not 100%).

If you see the image in the manual, the “water appearing to go to the outer edge of the glass surface” is the exact effect you want, because this is what happens in nature. The only reason you see the inner edge at all is due to the glass/air interface causing total internal reflection.

/Z

[dave-3d]

Zap,

Is there anyway to disable (or directly alter) the specular kick you get in an Arch & Design material ?

I always find that if I use an A&D material for glass (physcial 2 sided) I get a great big white specular burn-out caused by my omnis/spotlights, even if Glossiness is at 1.0. And if I am unlucky enough to get the right angle to hit a flat plane (acting as a window), I get a complete white out. It is a very tell-tale attribute of this material, and “looks” odd.

Being able to switch this specular kick off, or adjust it would be great - I would still get any reflected hotspots from my environment map.

Thanks,

Dave

[Bao2]

David: Relative Intensity of Highlights=0 ?

[SvenKalkschmidt]

Exactly - it is the correct render!

The reason it looks like this is your white environment, which reflects on the edges of the glass which makes you not actually see the edge at all. This isn’t the “water going outside the outer edge”, it is the water appear to go outside the inner edge - which is something you will see in ALL photos of a glass with liquid.

This is a photo of what I want to achieve.

http://flickr.com/photos/kylemay/2045520632/

or this

http://flickr.com/photos/europa70/2534243741/

I am using exactly the same setup, why do i get a different result?

If you want it to look “less odd”, put something in that makes the glass’ outer edge visible. Like a slight color tint to the glass (i.e. not make the glass transmittance not 100%).

But I want a clear glass, tinting is not an option.

If you see the image in the manual, the “water appearing to go to the outer edge of the glass surface” is the exact effect you want, because this is what happens in nature. The only reason you see the inner edge at all is due to the glass/air interface causing total internal reflection.
/Z

I understand that. You have to admit, that it looks quite odd though. Every single person (except you) considered this looking wrong.

I am sorry, if anything I wrote is plain stupid. I do not have a good grip on MR and the mia material (and reality).

[dave-3d]

David: Relative Intensity of Highlights=0 ?

Thanks Bao2,

But the A&D material computes specular using the Reflectivity (including BDRF) and Glossiness values. I want reflections so reflectivity has to stay on at 1.0, but even with Glossiness at 1.0 I get a hot spot area. Using the old raytrace material I can dial out the specular (or make it a pin point) but it doesn’t render as quickly as the A&D material - especially with nested glass and chrome objects behind the original glass material.

Where do you adjust relative intensity ? Is this a global setting, I would only prefer to use it locally to selected materials.

Dave

[JeffPatton]

Is there anyway to disable (or directly alter) the specular kick you get in an Arch & Design material ?

I always find that if I use an A&D material for glass (physcial 2 sided) I get a great big white specular burn-out caused by my omnis/spotlights, even if Glossiness is at 1.0.

You could turn off the specular attribute on the light source.

[JeffPatton]

What I wonder, though, what you are trying to acheive, in principle?

I could be wrong but I believe he has a 1/2 dome, 360deg sky map that he wants to use. like this: http://jeffpatton.net/Blog-images/Skydome_ex01.jpg

If you use those in the 3ds Max environment they get stretched since it’s using spherical mapping. Therefore he’s wanting to map it to a dome. Evidently for whatever reason he doesn’t want it to contribute any lighting to the scene. Instead he wants to use the mrSky for the skylight instead of this dome, and of course the mrSun for the direct light.

Of course one quick way to do that is to just hide the dome, calculate & save his lighting from the mrSun/mrSky, freeze the calculation, then unhide the dome and render.

Another option is that he could take that skydome map into Photoshop and paint a ground plane so that when it’s placed in the 3ds Max environment it would be compatible with spherical mapping. Then he could use the background switcher to accomplish his goal.

Again, I’m just guessing at the desired end result & maps that he’s using.

[dave-3d]

You could turn off the specular attribute on the light source.

True, Jeff.

But that would effect all objects/materials. Some of my lights are actually set for the oppposite at present (specular only, no diffuse) - and some are excluded from certain parts of the scene’s geometry (Illumination and/or shadow casting).

A way to tone down that specular bloom in the A&D material directly would be welcomed with open arms.

Dave

[Bao2]

Where do you adjust relative intensity ? Is this a global setting, I would only prefer to use it locally to selected materials.

In the Arch&Design material in the Advanced Rendering Options and now in Advanced Reflectivity Options set the Relative Intensity of Highlights to 0 and render. I really think if I understood you, it is what you are looking for.

[Bao2]

PNG remains a viable format. Forget JPG.

No. Forget PNG or you have troubles. Instead PNG you can use TIF if you are needed of 16bits. I agree EXR is the best just now if you are to choose one and only one format. But my question was JPG versus PNG and I really don’t understand why people like troubles, because PNG is troubles (perhaps because max filter import of PNG).

[Bao2]

or this
http://flickr.com/photos/europa70/2534243741/

I took about 60 shots and I’m not really happy with any of them

Can you imagine the guy putting the wine in the glass taking the photo and then the wine to the bottle again and clean the glass and begin again and all of this 60 times??? Man, learn 3D maaaaan!!! LOL

But I want a clear glass, tinting is not an option.

Your “diseapearing” glass is disappearing because it has the same color like your background at the edges. To it be visible you need make these two colors not the same pure white. So one option would be tone down the white at the background. Or the other option would be make the reflection in the 90 angle not 100%, just use the ability in the A&D material to be able to specify the reflectivity in the 90 angle and put it in 0.8 or so. I think you said you are with XSI so instead A&D it is called mia_material.

[dave-3d]

In the Arch&Design material in the Advanced Rendering Options and now in Advanced Reflectivity Options set the Relative Intensity of Highlights to 0 and render. I really think if I understood you, it is what you are looking for.

Which version of Max are we talking about ?

I only have Max9 to hand at the moment (Have some old files I must work on, but have access to 2009 design) and there is no “Relative Intensity of Highlights” option in the advanced roll-out in Max9 ? Pretty sure when I was working with Max2008 I didn’t spot that option either …

But it is exactly what I am looking for.

Dave

[SvenKalkschmidt]

Your “diseapearing” glass is disappearing because it has the same color like your background at the edges. To it be visible you need make these two colors not the same pure white. So one option would be tone down the white at the background. Or the other option would be make the reflection in the 90 angle not 100%, just use the ability in the A&D material to be able to specify the reflectivity in the 90 angle and put it in 0.8 or so. I think you said you are with XSI so instead A&D it is called mia_material.

Bao, I tried both of your suggestions - unfortunately they do not work.

• putting the 90 deg angle to 80% does not move the dark reflection to the outer rim
• toning down the background takes all the contrast out of the image, also the rim is only a slightly darker grey

please understand my scene is very simple, a cube with a constant in the background and a reflecting floor, the rest of the scene is just pure black (empty). by changing the size of the cube i can change the width of the dark reflection, but i can not move it to the edges of the glass.

[Bao2]

Which version of Max are we talking about ?

I only have Max9 to hand at the moment (Have some old files I must work on, but have access to 2009 design) and there is no “Relative Intensity of Highlights” option in the advanced roll-out in Max9 ?

You are right, Max 9 has not that. It is not simply copy the .mi file I suppose from Max2009 to Max9 because that is probably using some enhances in mentalray core.

[Bao2]

Bao, I tried both of your suggestions - unfortunately they do not work.

• putting the 90 deg angle to 80% does not move the dark reflection to the outer rim

80% probably still too much light. Try 0% and then up in next renders to find the one you want.

[MasterZap]

Where do you adjust relative intensity ? Is this a global setting, I would only prefer to use it locally to selected materials.

Dave

It’s in the “advanced” tab of the material. But it requires max 2008 or newer.

/Z

[MasterZap]

This is a photo of what I want to achieve.

http://flickr.com/photos/kylemay/2045520632/

or this

http://flickr.com/photos/europa70/2534243741/

Then do what he did; use some black cards to the right/left to get the black reflection. It looks like you have a complete surrounding white environment? Don’t. Use black cards to block of areas to give “interesting” reflections.

I was visiting a product photo studio, and they have this “photo box” which is a white sheet thing with lights behind, and then large black cylinders whos only purpouse is is to reflect in the pots/pans/mobil phones/toys/whatever is being photographed there.

This is a photo of what I want to achieve.
I understand that. You have to admit, that it looks quite odd though. Every single person (except you) considered this looking wrong.

It does look “odd”, but it’s still right. Heck, the classical every-day-observable case of the “inner” edge of a glass seeminly disappearing when you put liquid in is also really “odd looking”.

/Z

[MasterZap]

I could be wrong but I believe he has a 1/2 dome, 360deg sky map that he wants to use. like this: http://jeffpatton.net/Blog-images/Skydome_ex01.jpg

If you use those in the 3ds Max environment they get stretched since it’s using spherical mapping.

So don’t use an unaltered spherical mapping. I generally set it to mirror in V in that case. This gives you the expected sky, and then the sky “mirrored” for the lower half of the “sky” (but you’ll block that with some geometry).

You can also do it by turning repeat in V off and modifying the V offset and scale (don’t remember the value, could be 0.5 and 0.5 or maybe it ends up being 0.25 and 0.5, or something… try it… )

/Z

[JeffPatton]

So don’t use an unaltered spherical mapping. I generally set it to mirror in V in that case. This gives you the expected sky, and then the sky “mirrored” for the lower half of the “sky” (but you’ll block that with some geometry).

You can also do it by turning repeat in V off and modifying the V offset and scale (don’t remember the value, could be 0.5 and 0.5 or maybe it ends up being 0.25 and 0.5, or something… try it… )

Good idea(s).