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    Night reflector

    Hey

    Is it possible to make reflector material like police cars/officers and fire trucks have?
    Like this:
    https://bicyclesafetyinstitutedotorg...g_3895crop.jpg

    It starts glowing when you spot light on it at night, and at the day it looks like normal white.
    Like this:
    https://s-media-cache-ak0.pinimg.com...bde4dcae62.jpg


    Thanks for help

    #2
    nobody knows?

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      #3
      It's called a retro-reflective material, and it's key characteristic is that it reflects nearly 100% of the light it receives. Unlike a chrome or glass material however, a retro reflective one is designed to scatter this reflected light, such that the material appears to glow when viewed from a vehicle (with lights on) or taken from a camera (with flash on).

      I haven't tackled this in UE4, but I imagine you'd either overdrive the base color so that diffuse lighting is pronounced, or somehow get a shadowed albedo term to drive emissiveness.
      George Rolfe.
      Technical Coordinator at Orbit Solutions Pty Ltd.

      Comment


        #4
        Originally posted by duke22 View Post
        It's called a retro-reflective material, and it's key characteristic is that it reflects nearly 100% of the light it receives. Unlike a chrome or glass material however, a retro reflective one is designed to scatter this reflected light, such that the material appears to glow when viewed from a vehicle (with lights on) or taken from a camera (with flash on).

        I haven't tackled this in UE4, but I imagine you'd either overdrive the base color so that diffuse lighting is pronounced, or somehow get a shadowed albedo term to drive emissiveness.
        If my math is correct (disclaimer: it probably isnt), PBR materials such as they are in UE4 reflect 10% of the light that hits it.
        So you have good news and bad news there. The good news is that UE4 has a built-in multiplier for this 10% reflection: specular. You can multiply this between 0-1, where 0.5 is the default value. The bad news is that, unlike the emissive material input, it's clamped to 0-1. That means to get the output you want you'd have to get in to the source code and un-clamp the specular material input and then plug (I'm guessing) '500' in to specular.

        Don't take me at my word though.

        I guess if you were smart about your Eye Adaptation and your ambient lighting conditions you could fake it with an emmisive material that takes in a fresnel function to mask out side view angles.

        Visit my portfolio: jhgrace.com

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