Most realistic aluminum can shader?

[frank]

Hey guys!

I've been experimenting with photorealistic aluminum can shading for an upcoming short film.
The can will be composited into camera-matched footage and rendered with an HDRI/reference photo captured on-set.

I've attached an image of what I've come up with so far, using the Aluminum shader in Simbiont.

It doesn't "feel" right so far. I need to boost the specular/highs, and play with adding a subtle smudge/grime layer over the top with a custom reflectance map.

Can you guys recommend a better shader or method for trueSpace 6/7?

[Draise]

Blinn shader and an incidence based reflection or an anisotropic specular on top might make it better.

Your specular look a lot like metallic plastic with reflection. It's nice, but you need yes... tighter smoother molecules chunks with angles. Like aluminum. That means strong sharp specular with angled reflections that might have a subtle anisotropic blur to the reflections closer to the eye to surface.

Sometimes understanding how light bounces off a microsurface will clarify what you need to try do on the shader. And trying to get that in the software is something else usually but it's all tricks and illusions to master. I think the modelside works on a phong shader model but I'm not sure.

But they look great thus far! Really nice can model. Really believable.

[Finis]

Good model. Believable crushing.

"incidence based reflection" = Fresnel in many renderers.

Consider that parts of the surface are bare aluminum, the top and bottom, and parts are the coating or decal with the images and text, the side. The coating is probably plastic. So some light hits aluminum, some hits plastic, while other light passes through plastic to bounce off of aluminum and return. Two texture layers: metal and plastic. It is also possible that the whole exterior is coated and there is no bare metal.

[frank]

Great feedback, guys! Thank you!

I did experiment with an anisotrophic layer for the top and bottom of the can, to better simulate a brushed aluminum look to help "scatter" the light out better, but ended up going with a brushed bump map instead.

Here's where I'm at so far. (Three layers: First is basic aluminum, second is aluminum with a label mask, so that where the "print" is, there is a bit more diffusion/brightness and less refl + spec. The third layer is a grime/smudge layer.)

The other half of the equation in selling the effect (it has to do with telekinesis / making things float) is getting the physics + animation right.

I will experiment further with incident-based reflection. I remember using that (Yamaneko Fresnel?) for a car shader and it had a very nice look in that the reflectance changed realistically when the camera was low to the surface.

Again, I appreciate the feedback so far!

[spacekdet]

Well, there's your problem right there.
It's the wrong brand of root beer.

[frank]

Ol' Spacekdet! How ya doin, man?!?

I actually like IBC! Didn't know y'all had that up in Yankee land!

[marcel]

Aluminium have no reflect. It is not polished. It is the varnish on the can that create this illusion.
For a photorealism image you can create a transparency object as a new skin around a matte aluminium can. You will have more control for the textur.
In TS you can use the multi layer paint shader with aluminium option for the can and a dielectric or glass shader with a little refraction for the varnish. The transparency skin don't cast the shadow.

[frank]

Aluminium have no reflect. It is not polished. It is the varnish on the can that create this illusion.
For a photorealism image you can create a transparency object as a new skin around a matte aluminium can. You will have more control for the textur.
In TS you can use the multi layer paint shader with aluminium option for the can and a dielectric or glass shader with a little refraction for the varnish. The transparency skin don't cast the shadow.

Thank you for the suggestion, Marcel!

I've taken your advice and started experimenting with two separate objects (ie. base = aluminum via Multi-Layer paint shader, duplicate object = clear coating (shadow-casting disabled).

However, I'm getting unexpected results with the multi-layer paint shader. For example, I turn Reflection all the way down to zero, and still get reflections, based on the Transmission value.
If I turn Transmission all the way down, I get no reflections, but the entire thing is very dark.

I've attached a screengrab showing my settings. (Original can is on the right, new work-in-progress using your suggestion is on the left.)
The goal is to get this looking like basic raw aluminum, before I throw the Dielectric/clear/gloss on top of everything.

I appreciate any additional help you can provide!

[frank]

OK... I see "metallic f." is apparently the value that affects reflection. I turned this value down and reflection is gone.

I'll continue to experiment.

[frank]

This is probably about as good as I can make it, though I know it's still not where it SHOULD be (at least, compared to the real reference can sitting right next to my computer.)

I didn't have any success with anisotrophic, multi-layer paint, or Caligari metal shaders, so I stuck with Simbiont's Tinfoil.
The duplicated "clear coat" object is shaded with Yamaneko Fresnel, and the grime and smudge layer is applied over that.