So, I recently acquired Poser11 a couple months ago and have been loads of fun playing with the new render options, however, I stumbled upon a shader from a few years ago to render a jade material using the Scatter node. So far other materials that use the scatter node seem to work fine, but this one material for jade just does not want to cooperate.

I don't believe it's the lighting because I have used multiple lighting sets from Poser defaults to various indoor/outdoor HDRI light sets. This particular set I used is a bit softer than some of the others I used, but I can assure you no matter what lighting set I use, I get the same results. The material just looks like it's painted on, as if I don't even have the Scatter node plugged in. I'm not rendering in Superfly, since when this material was made it did not exist, just standard Firefly with the options shown in the image below. I have also tried other objects too with similar results as what I have posted here.

The shader is copied directly from the RuntimeDNA forum: http://forum.runtimedna.com/attachment.php?attachmentid=57809&d=1313117544

So, what am I missing here? I'm at a complete loss because it looks absolutely NOTHING like the other images people posted of their results.

Don't have P11 but AFAIK, standard issue shaders don't play well with Superfly. That's all I got but I guess plenty other folk here will have a workaround.

Hi Sam, unfortunately our OP is trying to duplicate results with Firefly as the render engine ... and the results should be the same as with earlier versions of Poser. My time is limited this morning as I'm helping my roomie get her car started in a few, but I'm looking into this as best I can.

Ok ... the main difference I see ... and this is without connections or variable numbers ... is the Root node has all WHITE colors. Shouldn't make a difference, but who knows. Here is my result based on the settings presented:

Guys guys guys. The OP has gamma correction turned off. Whoops. Big difference.

Would help if we had a link to the thread, not just the shader. I suspect I had something to do with it but I can't recall nor find it.

Oops, didn't think about putting up the thread link too: http://forum.runtimedna.com/showthread.php?63209-SSS-on-non-human-things/page2

I actually didn't have gamma correction on since it was off by default, never thought of turning it on, I'll do that and see what happens.

Ok, so I went in and made a few slight changes. First, I turned on gamma correction, left it at 2.20 since it was default. Also changed the lighting, it's an IBL with a an infinite light, I changed the infinite to a spot so it would cast a shadow on one side and hopefully show some SSS as the light passes over it. Also made a slight change to the material and made the Cloud_color white instead of a light green.

I can kinda see it being a jade on the shaded side, but to me it still looks like the material is just painted on rather than the Scatter making the light pass through it. It's very odd.

I don't know if this will help, but it looks like the raybias on the reflect node is unit dependent. If you're using different units than the creator, you may get different results. Bagginsbill usually uses inches.

If we're trying to match previous results I would not change the light green to white yet.

As for how far the scatter goes or how blurry it looks you have to adjust those things. The Scatter node Scale and Texture_Detail are numbers you need to adjust.

Here I show scale at various settings, high (left) to low (right).

Oh, see, I bet people were changing those numbers and not saying they did, which is where I was getting tripped up. I'll play with them and see what happens, but you probably solved it for me.

If you don't mind, could you explain what those two numbers do exactly? This is my first time using the scatter node, so I'm not too familiar with it.

Also, what does RedPhantom mean when he's talking about units on the Reflect node? I wasn't aware that a reflection needed lengths :P

I looked back over that thread, which was largely me posting. I did use differing values on various props. I don't know what values exactly but I can tell by looking at the images that they were not identical values. But the shader structure, by which I mean the selection of nodes and their particular interconnections, is the same in all examples.

The parameters that control various node behaviors are always going to be adjustable. When you look at a shader there is always some latitude in what values to use. For me, the particular range of values I stay within is always motivated by physics and the reproduction or simulation of real-world materials. But in a material like jade, the real world admits to a truly wide range of values when examining the subsurface characteristics. On the other hand, the surface or "specular" behavior is very much the same as almost all other materials and should stay within plausible values for the Fresnel effect.

The scatter node "Scale" parameter controls how far light seems to travel through the volume of the material before losing a specific fraction of its original energy. Unfortunately it doesn't do so using an intuitive parameterization. When you increase the Scale, you decrease how far the light goes. When you decrease the Scale, you increase how far the light goes. The admissable values for Scale are anything above 0. (If set to 0, the equation breaks down and no light comes out at all) The original research paper that led to the Scatter node algorithm in Poser included real-world measurements of various materials. If you set the Scale to 1, you will reproduce those measurements exactly.

But as I said, real marble or jade don't follow one single and unique "scale" so it's acceptable (and even mandatory in some cases) to change Scale to be more or less than 1.

The Texture_Detail parameter does not have a direct physical representation. The blurring of the texture details is controlled by this value and it is not motivated so much by an appeal to real physics, since the Scatter node does not actually bounce light around inside the volume of the object. Rather, it's an approximation that requires you, as the artistic director of the production, to choose how you want the texture to be revealed as a subsurface effect, rather than a surface effect. If you notice the texture or color pattern looking too "painted on" then you probably want to decrease the Texture_Detail. I have experimentally judged that the legal values are from 0 to 1, inclusive. However, I found that negative (hypo) values or above 1 (hyper) values produce some "surprises" that an artist might actually find appealing. The hypo and hyper values produce what are properly called "artifacts" but if you like what comes out then cool, use it.

Here is a comparison of various Texture_Detail values starting with 1, then .5, .25, .125, .0625, and finally .03125. (The mathematically observant reader might notice I was using powers of 1/2).

Oh and the subject of ray bias was raised, although it has nothing at all to do with jade per se.

The FireFly engine has some peculiar issues having mostly to do with smooth shaping of polygons. The problems created by flat polygons pretending to be curves appear when you use displacement, subdivision, or the FireFly "smooth polygons" options. CG is full of cheats and approximations in order to gain speed. The numerous cheats and fakes in FireFly geometry can occasionally produce artifacts in the raytracing reflection and refraction calculations. So all the raytracing nodes have a ray bias feature, which basically is another artifact to counteract other artifacts. Basically it makes a point on the surface ignore other nearby parts of the surface. These parts are sometimes not real but instead they are failures of the geometry approximation algorithms. Visual artifacts (flaws) are often produced by reflecting into fake geometry that also happens to be really close. Simply ignoring that fake geometry when it's really close is sometimes a less offensive artifact. Exactly how close is close? That's what you get to answer by setting ray bias. If you ask what's the right value, the answer, unfortunately, is "it depends". Anyway, the values I use are displayed in inches because my Poser Display Unit (known as PDU) is set to inches. If you're copying a screen shot of mine, you need to be constantly aware that a number in a different unit system is a different number. If you have your PDU set to feet, for example, and you type .3, then you really mean .3 * 12 inches which, on my screen shot, would actually be 3.6 and that is NOT a good value for ray bias.

However, in your scene, where you have an isolated sphere with nothing to reflect but itself, any value of ray bias will look pretty much the same. So bringing it up was not going to address anything going on in THIS particular image.

Wow, the explanation of just the Scatter node's properties made a big difference, looks like it's actually working properly now!

My problem is, I just plain suck at math, so things like this are, in some ways, over my head, but I still understand when someone explains it to me (odd, I know). I was better at geometry than I was at algebra, it's just the way my mind works. I'll keep playing with this and hopefully make some nifty pics :D