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Hi,

I have a project where I need to included a retroreflective material like this: http://bowiestie.files.wordpress.com/20 ... -5_001.jpg

I saw an old thread from V1 where someone attempted this, but didn't get anywhere. All I could find online was a reference to a index of refraction of 2.

Anyone have any ideas?

I guess you may start with one of these.
http://resources.maxwellrender.com/sear ... v2=0&tipo=
http://resources.maxwellrender.com/sear ... v2=0&tipo=

He said retroreflective, not reflector.

here is a retroreflective attempt;



There are two geo's inner object is a rough shiny metal, OUTER OBJECT HAS SSS, low nd (1.15), high coef (90000), high POSITIVE assymetry (0.85)

eric nixon wrote:He said retroreflective, not reflector.

Am I missing something?
http://en.wikipedia.org/wiki/Retroreflector

Is wikipedia wrong

Well, maybe the correct term is not retroreflective.. But thats the effect he wants..

Anyway I forgive you

Why do you think he doesn't mean retroreflective but something else?

I was thinking that sss with positive assymetry could give this effect;

Now I see that they are the same thing., you were right... but do you mean to say that a normal map can do it? I mean the SSS way seems to work?

I tried it with 2 geo's and a normal map, and no sss, it appears to work, but only with HDRI not emitters.

render was 5min to sl18.. needs a better normal map.



Now I know the sss render is nonsense, sorry about that, I did it a long time ago, thanks Tom, I've learnt something,.... cant wait to test the new maxwell...

Thanks for the suggestions.

- Tom sorry I did a search for reflective not reflector. My bad.

I'm yet to model the object and try myself. I have a request from a client and was wondering if anyone had achieved it yet. Ill try today and let you know how I get on.

Hi Eric,

Thanks for your suggestions. I think that would be the right approach if I was trying to model an object like this





But Im looking to have it as a detail on an item of clothing so more similar to the link I posted previously.



I like your mirror layer with the reflection being bright at 0º and dark at 90º I had a play with that really quickly today and its not bad.







I think the easiest would be if there were some way to fake it with a material that had an emitter as the 0º colour and dark on the 90º I tried a few things with emitter layer combined with the mirror layers in different strengths, but wasn't able to produce anything convincing.

Are you sure that picture is not exaggerated in any way, what exactly are they reflecting so strongly? Is it a big emitter behind the camera? It's not like they can emit more light than they receive.....

Andy, I think the effect is the same but at different scales, even the fine fabric retroreflect is effectively a LENS on the outer surface.. This is needed to achieve the effect of light coming back out from the direction it went in - (think cats-eyes).

It's quite hard to simulate this material accurately using normal/bump mapping. Ideally, it requires to be modeled accurately down to the microns or needs a dedicated shader.

I tried to model a single retroreflective lens (#2), but it's not working so far.



My failed attempt: