[jdp]

just a simple guess:

given the fact that we need to avoid high reflectance values, it is not possible to set an automatic limit for reflectance... or better a simple switch to "autolevel" reflectance if we want to be sure to prevent improper values?

[giacob]

@giacob, given mihai explanation it is quite simple, they are not layered over, they are mixed toghether as a sauce, if I am not completely wrong

On the other hand, how many people are aware that the squeezy bottle for their tomato sauce bottle contains at least 5 layers.

damn those 5 layers can be a tricky job to reproduce...

thx, mihai..

so all plastics are a mix of materials and that is what gives theyr visual properties ? the amount of glossiness or roughness depend on the properties of the various mixed material? .. never heard of that before though ... but not an expert at all of the matter...

[Mihai]

No, not all plastic objects. You could make a plastic with one rough bsdf, and put a coating over that if you want, to mimic the smooth finish. The two bsdf approach just gives you more control because perhaps that finish is not completely smooth, or you want to add scratches to it, or map the roughness, or.....

[nik_h]

I'd be grateful if someone, preferably with a diagram, could show the physical, real world interpretation of multiple BSDF layers and how the weight values affect the end result. Also as a few people have already mentioned, if I want to model, say, a solid sphere of polypropylene why can't this be achieved in a single layer when it is a homogenous material? The manual really needs a big update on the material system.

Nik

[giacob]

No, not all plastic objects. You could make a plastic with one rough bsdf, and put a coating over that if you want, to mimic the smooth finish. The two bsdf approach just gives you more control because perhaps that finish is not completely smooth, or you want to add scratches to it, or map the roughness, or.....

but they are not just layered one over the other .. which i would understand.. they are blended toghether.. which i dont understand quite...
if they were just layered u would had not to set % of the two ... u had just to set the transparency of the upmost layer.. because if the upmost layer would be totally opaque the one under wouldnt count at all..

[raja]

thanks a lot mihai. this was really needed.

i cant fully understand that a material can have a certain number if materials layered one over the other...i would fully comprehend if i had a rough layer and over this a glossy trasparent layer ........ what dont seems to me to be logical is blending two layer togheter , ..[/b]both not trasparent, to get a plastic surface....

giacob,

after reading mihai article this is how i would understand two layers for plastic - one layer will take care of the texture that platic surface has, another layer will take care of glossy part, simulating thin layer of molecules which are closely packed on top of surface. think of it as a rough mountain covered with a glossy cloth- from far away, this is plastic surface.

[rivoli]

so all plastics are a mix of materials and that is what gives theyr visual properties ?

something like that, and they're not layered one on top of the other, but actually blended or mixed together:

A plastic is made up principally of a binder together with plasticizers, fillers, pigments, and other additives.
The binder gives a plastic its main characteristics and usually its name. Thus, polyvinyl chloride is both the name of a binder and the name of a plastic into which it is made. Binders may be natural materials, e.g., cellulose derivatives, casein, or milk protein, but are more commonly synthetic resins. In either case, the binder materials consist of very long chainlike molecules called polymers. Cellulose derivatives are made from cellulose, a naturally occurring polymer; casein is also a naturally occurring polymer. Synthetic resins are polymerized, or built up, from small simple molecules called monomers. Plasticizers are added to a binder to increase flexibility and toughness. Fillers are added to improve particular properties, e.g., hardness or resistance to shock. Pigments are used to impart various colors. Virtually any desired color or shape and many combinations of the properties of hardness, durability, elasticity, and resistance to heat, cold, and acid can be obtained in a plastic.

[Frances]

deleted

[giacob]

so all plastics are a mix of materials and that is what gives theyr visual properties ?

something like that, and they're not layered one on top of the other, but actually blended or mixed together:

A plastic is made up principally of a binder together with plasticizers, fillers, pigments, and other additives.
The binder gives a plastic its main characteristics and usually its name. Thus, polyvinyl chloride is both the name of a binder and the name of a plastic into which it is made. Binders may be natural materials, e.g., cellulose derivatives, casein, or milk protein, but are more commonly synthetic resins. In either case, the binder materials consist of very long chainlike molecules called polymers. Cellulose derivatives are made from cellulose, a naturally occurring polymer; casein is also a naturally occurring polymer. Synthetic resins are polymerized, or built up, from small simple molecules called monomers. Plasticizers are added to a binder to increase flexibility and toughness. Fillers are added to improve particular properties, e.g., hardness or resistance to shock. Pigments are used to impart various colors. Virtually any desired color or shape and many combinations of the properties of hardness, durability, elasticity, and resistance to heat, cold, and acid can be obtained in a plastic.

also marble or peperino are a mix of materials... ....and so are many other materials ..... but we usually preferr to put a map to reproduce how it looks .... we dont try to make piroclastyc inclusions , rough parts and all the materialis that are in i it ... it would be unusefully complicated..

[Maximus3D]

For simple materials like that why don't you just use the Wizard as in the beta to get create a Plastic and then slap on a marble texture on it and it's done. And if you then need the more powerful materialeditor for other types of surfaces then use that. Don't try to make it sound more complex than it actually is.

Btw Mihai, good explanation of the material system.

/ Max

[rivoli]

but we usually preferr to put a map to reproduce how it looks .... we dont try to make piroclastyc inclusions , rough parts and all the materialis that are in i it ... it would be unusefully complicated..

yes, I guess you're right. the only problem with single bsdfs shiny/glossy mats is that there's no way to have non tinted speculars.

[nik_h]

Don't try to make it sound more complex than it actually is.

Well I've two degrees in mechanical engineering which included a lot of work on materials and it seems complicated to me. It would help greatly if we had a properly written manual.

Nik

[giacob]

For simple materials like that why don't you just use the Wizard as in the beta to get create a Plastic and then slap on a marble texture on it and it's done. And if you then need the more powerful materialeditor for other types of surfaces then use that. Don't try to make it sound more complex than it actually is.

Btw Mihai, good explanation of the material system.

/ Max

dont try to make sound as simple as actually is not, mostly from the theoreticall point of view, is my easy reply..

[aitraaz]

A plastic is made up principally of a binder together with plasticizers, fillers, pigments, and other additives.
The binder gives a plastic its main characteristics and usually its name. Thus, polyvinyl chloride is both the name of a binder and the name of a plastic into which it is made. Binders may be natural materials, e.g., cellulose derivatives, casein, or milk protein, but are more commonly synthetic resins. In either case, the binder materials consist of very long chainlike molecules called polymers. Cellulose derivatives are made from cellulose, a naturally occurring polymer; casein is also a naturally occurring polymer. Synthetic resins are polymerized, or built up, from small simple molecules called monomers. Plasticizers are added to a binder to increase flexibility and toughness. Fillers are added to improve particular properties, e.g., hardness or resistance to shock. Pigments are used to impart various colors. Virtually any desired color or shape and many combinations of the properties of hardness, durability, elasticity, and resistance to heat, cold, and acid can be obtained in a plastic.

WTF?!?!?

[Mihai]

So why can Maxwell not simulate a simple homogenous plastic of whatever shinyness with only reflectivity and roughness? When you get to the indepth discussion of layers, it would be helpful if you would explain in detail the relationship between the first bsdf and the second one and why a surface's roughness needs to be represented on a separate layer if the shine is simply a result of that roughness. It just seems like a quirky workaround to me until then.

Well I imagine it this way: You have a rough plastic material, the surface is rough enough that it looks almost like a lambert, no sign of specular reflections. Now you start polishing it's surface, you are aligning a very thin "layer" of this material so that it gives you specular reflections, but much light will still go through this first smooth part and bounce off the rest of the material, which is more porous, so that light will be reflected back more diffusely.

In any case, I don't find this system overly complex, and we could ask the same question for any other renderer. Why do I need to set a separate diffuse color, and a specular reflection? Would such a material also look correct, because the more an object reflects back light as specular, the less it reflects back it's own color. Instead it reflects back the environment. This is taken care of in Maxwell. This material system is not complex, just different.

There's just too much panic, while completely ignoring that a LOT of materials you find in real life could not possibly be made with the old system.