[lebbeus]

One of these days I'm going to sit down and see if I can reproduce this kind of material with Maxwell.

http://en.wikipedia.org/wiki/Retroreflector

any suggestions?

[sampson]

...you got me thinking the same thing when i read your thread in the other section... I shall try & give it a go this week. Have a few bits of reference at work i can use.

[ivox3]

I'm interested.



....hey Sampson.

[Mihai]

This seems more of a modeling task than making the right material.

[ivox3]

so Mihai, ....then your saying, if modeled correctly, then it should work?

[Mihai]

sort of....I'm saying it should work, if modeled correctly.

[michaelplogue]

Sure... all you have to do is model a trillion tiny glass spheres......

[lebbeus]

maybe some sort of particle distribution over a surface…hmmm

I did a test tonight of a textured coating (two layers: one BSDF, the other just a coating with a weight map) it wasn't exactly what I was going for (although it seems as though this might work for the new type of traffic signs).

I'll do more tests and post some images later this week.

[iandavis]

michaelplogue,

Man, if your too lazy to do it... I'LL DO IT. shouldn't take too long in lightwave... just make a tiny 8 polygon sphere and open up the clone tool, type 1,000,000,000,000 copies, click OK... hmmmm.... what the... some sort of delay...

funny... the hourglass is still there... what gives?

I wonder if maxwell will crash with 8 trillion polygons?

;P

ian.

[michaelplogue]

[Tim Ellis]

I'm not sat with a copy of Maxwell so I can't test these, but I've knocked up examples of the reflectors shown in the wiki.

http://rapidshare.de/files/22412304/Ret ... s.rar.html

RAR compressed file containing .OBJ .DXF .LWO & .3DS (3ds might not work.) These were modeled with Blender & I've always had issues importing Blender meshes straight into studio (missing faces & the annoying tri issue), so use the plug-in for your 3D application to send them to studio.

A set of 3 different retro reflectors in mesh format. Duplicate each mesh as needed.



90' reflectors. (160 1/2 cubes in a flat square formation - 640 faces.)

Spherical reflectors which need to have 2x refractive index of the medium from which the radiation is incident. (224 spheres in a flat square formation - 14336 faces.)

1/2 spherical mirrors. (224 1/2 spheres in a flat square formation - 7168 faces.)

As far as materials, either chrome or similar for the 90' or the 1/2 sphere versions and glass with exactly 2x ND of air.

I'll run some tests with these when I get back to my copy of Maxwell.

Hope they are useful and most of all work.

Tim.

[lebbeus]

wow, thanks!

downloading now and will run a test tonight/tomorrow.

[michaelplogue]

The trick for retroreflection is to have a complete sphere halfway embeded in some opaque material. This way, no matter what angle a beam of light hits it, it will refract , reflect, and refract once again - exiting the bead at exactly the oposite direction it initially entered.

Here's an example on how it's used on street lines.



So Ian - after you generate your trillion spheres, you'll need to duplicate them, boolian the duplicates from a thin box, then bring back your original trillion spheres with a glass shader. Should work fine then....

[raja]

edit (normal maps aint working)

[michaelplogue]

This should actually be easy enough to test using a single sphere 'embeded' in a box. Place a light source directly behind the camera and let'er rip.