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Thread: Texturing Gems - Looks more like glass

  1. #1
    Fórum áss clówn Hopper's Avatar
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    Texturing Gems - Looks more like glass

    Hi guys,

    I'm tring to texture a gem (made by the gem primitive), but no matter what I do it winds up looking like clear glass. I tried using the Dialectric Node also but it turns out just as clear.

    Here are my settings...

    Refraction index: 2.14
    Diffuse: 10%
    Specular: 75%
    Color Highlights: Off
    Glossiness: 64 (Medium)
    Reflectivity: 20%
    Transparency: 100%
    Color Filter: On
    Smoothing: Off

    I'm using my HDRI as my reflection but it's just not getting it. Any suggestions?

    Thanks
    Playing guitar is an endless process of running out of fingers.

  2. #2
    NewTek Developer jameswillmott's Avatar
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    You could use one of the materials with Dispersion to get some coloured refractions happening, you'll need quite a few ray recursions as well...
    LightWave3D training, assets, news and discussion at www.liberty3d.com
    My opinions are my own and do not represent the opinions of any other entity, Liberty3D is not officially endorsed by NewTek.

  3. #3
    Super Member Nangleator's Avatar
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    I was just going to say Dispersion. Make sure there's some non-zero amount of roughness, then add lots of dispersion. Gems get their look from lots of internal reflections, but you might be able to cheat it with a refraction image instead of a high RRL.

    Those internal reflections can make the render crawl.

  4. #4
    Registered User Gui Lo's Avatar
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    Quote Originally Posted by Nangleator View Post
    Those internal reflections can make the render crawl.
    True.
    Play with the Ray Recursion Limit to reduce render times. A low setting can be used at first to get the look and them increase it for the final render.

  5. #5
    Registered User OOZZEE's Avatar
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  6. #6
    Pixel and Poly Pusher JeffrySG's Avatar
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    Quote Originally Posted by neverko View Post
    You can also fake dispersion by rendering 3 images with slightly offset indices of refraction
    That's very interesting! Never heard that tip before!

  7. #7
    Registered User Andyjaggy's Avatar
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    Well if all your using is an HDRI and no lights then the spec values won't have any effect anyway will they?

  8. #8
    Member Simon's Avatar
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    Just like the real thing, the angles of the gem's facets are crucial in getting lots of internal reflection and hence sparkliness. Diamonds are cut with a lot of shallow angles for this reason.

    Attached is a simple test scene I made a while ago using a plain dielectric material for the gems. I used (I think) models from this site which even tells you what refractive index to use for each one:

    http://www.3dlapidary.com/HTML/Stones3.htm

    ... and the HDR probe I used (not included in my scene) I got from the below site, it's the one called beverlyHills_sun_probe_FINAL.hdr:

    http://www.unparent.com/
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  9. #9
    Fórum áss clówn Hopper's Avatar
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    Thank you very much!

    I am going to go through every one of these and see how it goes. I'm especially interested in Neverko's solution... How did you come up with that anyway? Those kind of solutions can't possibly be accidental..

    Oh .. and I eventually figured out the specularity thing... It's now glued to 0. I changed the HDRI to a solid white PNG and it started to look better.

    I never even thought to crank up the RRL. (and that's why I'm still a noob).

    Thanks for posting the gem scene Simon. Real examples to learn by are awesome.
    Playing guitar is an endless process of running out of fingers.

  10. #10
    normally i am different ingo's Avatar
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    Quote Originally Posted by Hopper View Post
    Hi guys,

    I'm tring to texture a gem (made by the gem primitive), but no matter what I do it winds up looking like clear glass. I tried using the Dialectric Node also but it turns out just as clear.

    Here are my settings...

    Refraction index: 2.14
    Diffuse: 10%
    Specular: 75%
    Color Highlights: Off
    Glossiness: 64 (Medium)
    Reflectivity: 20%
    Transparency: 100%
    Color Filter: On
    Smoothing: Off

    I'm using my HDRI as my reflection but it's just not getting it. Any suggestions?

    Thanks
    Hmm, seems you got your settings from the old tutorial from Dave Jerrard. If you have that tutorial just read on, its all explained there.

    And don't forget the fresnel effect !!

  11. #11
    Fórum áss clówn Hopper's Avatar
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    Quote Originally Posted by ingo View Post
    Hmm, seems you got your settings from the old tutorial from Dave Jerrard. If you have that tutorial just read on, its all explained there.

    And don't forget the fresnel effect !!
    You are absolutely correct sir. I am but a lazy IT guy, thus Googling "Lightwave gem texture render" was faster than futzing around with settings for three hours.
    Playing guitar is an endless process of running out of fingers.

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