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Thread: Luminosity by object thickness?

  1. #1

    Luminosity by object thickness?

    Hey all,

    Im trying to make some really neat looking glowing slime, something of the radioactive, toxic nature.

    I have been playing around with making the surface luminous which is looking good. The subsurface scattering materials like simple skin and sigma are getting me close but they dont carry the luminosity well.

    This may be a long shot, but what Im really looking for is a way to control the luminosity based on object thickness. The thicker the piece of the object, the more luminous and opaque, the thinner the less luminous and more translucent/transparent.

    These are images of UV reactive slime and a pretty good example of what I'm hoping to achieve:
    http://i.ytimg.com/vi/mEWUoDU6qzU/0.jpg
    http://www.stevespanglerscience.com/...WSLM-500_3.jpg

    I have tried using the Thickness node (Gradient>Tools>Thickness) in the node editor, but it only seems to change the refraction index.

    Any tips or ideas would be greatly appreciated!
    Thanks!

    "Remember, wherever you go, there you are!"


    Check out my website and demo reel.

  2. #2
    Super Member SplineGod's Avatar
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    In the standard texture layers you do have a gradient input parameter thats based on surface thickness. Im sure you can do the same thing with nodes.

  3. #3
    Quote Originally Posted by SplineGod View Post
    In the standard texture layers you do have a gradient input parameter thats based on surface thickness. Im sure you can do the same thing with nodes.
    Thank you for the tip. I use the nodes so often, I forgot about all the gradient options for texture layers.
    Using the surface thickness gradient in both the luminosity and transparency channel. Its starting to look interesting and a bit closer to what I want.

    I'll continue to play around with it, thanks!

    I wish I could get a bit more of a sss effect, but its looking better.

    "Remember, wherever you go, there you are!"


    Check out my website and demo reel.

  4. #4
    Playing around with the surface thickness effect is giving me some pretty interesting results. The only down side is that the surface thickness acts like an "incidence angle" surface thickness based on the camera's angle. It would be great if I could figure a way to use a weight map for surface thickness luminosity.

    "Remember, wherever you go, there you are!"


    Check out my website and demo reel.

  5. #5
    TrueArt Support
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    I would take Spot Info World Position plug to RayCast node origin, then take Ray Direction and also plug to RayCast direction node, and return value from RayCast plug to Gradient..
    Remember that -1 means infinity. Values >0.0 is thickness of object along ray.

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    Last edited by Sensei; 06-10-2012 at 09:28 PM.

  6. #6
    Quote Originally Posted by Sensei View Post
    I would take Spot Info World Position plug to RayCast node origin, then take Ray Direction and also plug to RayCast direction node, and return value from RayCast plug to Gradient..
    Remember that -1 means infinity. Values >0.0 is thickness of object along ray.

    Thank you for the suggestion and screenshot, Im still trying to decode how it fully works. Its giving some pretty interesting results. I cant tell if its basing the thickness on worldly coordinates or by camera incidence angle.
    I tried attaching this to a sss material, like simple skin, but it looses the luminosity.
    Ill keep kicking it around and playing with the settings.

    "Remember, wherever you go, there you are!"


    Check out my website and demo reel.

  7. #7
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    Ray cast node is returning length of ray starting at given origin and going in given direction.
    If ray origin is from spot position and ray direction from ray that hit polygon, it'll be like transparency ray (without refraction, like refraction index = 1.0), but without all shading etc. just returning distance from spot to geometry directly behind it.

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