[mverta]

btw, I don't see why you couldn't render your r2-d2 with existing shaders.

For the reasons I explained. You can't do metal paint flakes yet - we don't have an "anisotropic direction" map (anisotropic reflections don't even work yet) and there isn't a way to have a color ramp based on fresnel's equations. For example, a surface is green when you look right at it, but turns blue as the angle to camera increases. A lot of automotive paint (R2's in particular) does this... goes from a bright blue to a deep purple/black in the "flash". It also requires a separate, glossy topcoat. This is silly to do with geometry - a layered shader is all it takes, which Maxwell can't do yet. Plus, you can't do R2's aluminum properly without anisotropic reflections, which aren't working. You also can't do the proper SSS for his flashing displays with the current setup. Eventually, all this may be possible.

_Mike

[John Keates]

The look of the object due to bounced light is not dependant on size for the same kind of reason that larger objects don't fall faster to the ground. The reflected light may have further to go but there is more of it as it is coming from a larger area.

In other words, a photon of light doesn't loose energy if travelling through a vacuum but diffuse light will be distributed over a large area as it moves away from the source. If you scale an object up then the amount of light bouncing off its surface increases in proportion with the degree to which it is dissapated across an equivelent distance.

So, for me, the renders look fine.

Sorry if the discription is unclear - it is the kind of thing which is best done with pictures.

[mverta]

John... thanks... I agree the renders look fine, and I'd considered the fact that on a larger surface the energy would basically scale up, compensating for its falloff, but I wasn't sure of the physics behind it.

Not sure why I can't shake this feeling about something not being quite right, but I'm going to try a couple of other contexts to test it.

_Mike

[andronikos916]

In the real world, if you could suspend a coin 10 meters above the ground under the sun, it would not cast a perceivable shadow. However, if alongside the coin you would suspend a 2 meters in diameter disc, it would cast a distinct shadow. So, in the real world, size matters. But one thing is size and another is scale. The question is: if you scale a whole C4D scene lets say 100 times (and I don't mean changing units) what parameters are *not* scaled?

The above paragraph copied and pasted from cgtalk.com Jorge Arango's example while discussing c4d and maxwell units.

cy,
Andronikos

[andronikos916]

John... thanks... I agree the renders look fine, and I'd considered the fact that on a larger surface the energy would basically scale up, compensating for its falloff, but I wasn't sure of the physics behind it.

Not sure why I can't shake this feeling about something not being quite right, but I'm going to try a couple of other contexts to test it.

_Mike

Mike I feel and I know what are you saying... please if you have time read the following thread. I hope this clear your mind my :"Lord"...

http://www.cgtalk.com/showthread.php?t= ... ight=units
cy,
Andronikos

[mverta]

Interesting thread, Andronikos...

Though I wonder if the coin's failure to cast the shadow has more to do with scattering of rays in the atmosphere from pollution and whatnot. That is, in a pristine environment, would it cast a shadow? Or perhaps its shadow is so soft and wide you can't see it?

Hmm... In any case, I think that "ground plane" test is in order...

_Mike

[Kabe]

It's not the shadow intensity I'm wondering about, as much as it is the indirect/bounced light. If a ray hits a surface with X energy, then the further away the indirect surface is, the less light it will receive.

Aaaah, that old misunderstanding... rays don't loose enery while traveling space (not very much at least).

Everyone who's thinking about his physics lesson "Hey, the intensity of light is depending by 1/square from the distance!" is mixing up things. The 1/square rule is an effect of geometry - Maxwell does take care for that by design.
DOF and atmospheric scattering aside, a small model has the same light distribution as a huge one. You might check that in real life.

So, the Maxwell scale is important so DOF is calculated correctly, that dieelectric absorption and SSS are defined in a reliable context and at some later version that fog has a scale. It has it's effects on lights, too (don't know too much about that side if the equation).

However, it is *not* influencing light distribution, which is scale independent.

A white piece of paper will cast a lot of bounce light on a surface 2 inches away, but not 2 miles away.

Your white piece of paper grows at the same scale if you just enlarge the scene... the same is true for your other examples.

Kabe

[johann.dugge]

andronikos, about the coin: I think you are missing that if you scale the coin up 100x (2cm to 2m), the distance to the ground would grow at the same rate, so your 2m "coin" is 10000m, 10km! away. no noticable shadow there i bet!

[mverta]

Well that certainly sounds like it makes sense...

I have to admit my grasp of the physics of it is tenuous at best... a well-known visual effects supervisor once told me, "it doesn't have to be real, it just has to look right." Obviously before Maxwell, when you can have both!

_Mike

[Mihai]

andronikos that's wrong, light doesn't lose energy in a complete vacuum, but if it's traveling through air for example it DOES lose energy.

That's what that 1/square rule means. I'm not sure what you mean by "it's an effect of geometry".

[Micha]

That's what that 1/square rule means. I'm not sure what you mean by "it's an effect of geometry".

It in vacum is it the same, it pure geometry.

[Mihai]

eh How can photons lose energy if they don't collide with anything (incl oxygen molecules).

[Micha]

Twice distance from the lightsource --> double area that receive light. The energy is stronger distributed.

[Thomas An.]

andronikos that's wrong, light doesn't lose energy in a complete vacuum, but if it's traveling through air for example it DOES lose energy.

That's what that 1/square rule means. I'm not sure what you mean by "it's an effect of geometry".

Mihai,

I suspect the Sun light that hits Mercury, is a little stronger than the light that hits Pluto.

Not sure if its related to loss of energy as much as the flux of rays per square inch
-

[Mihai]

I see what you mean now, you mean twice the distance, the photons spread over an area four times as large...

Micha, you're misleading me