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Diamond Ring with Fake Dispersion

20

http://www.youtube.com/watch?v=NRN8VODdlzA

By Kiril Viktorov.

About the Author

Avatar image for Bart Veldhuizen
Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.

20 Comments

    • Why does erveryone who makes something nice have to make a tutorial? There's not that much here, just fancy shader on the diamond and good execution overall.
      Should be able to disect it youself.

      • well you should understand that there are many others that cant do it just by seeing it!! and even if you could do it maybe you should consider the possibility to learn something new, maybe his methods are better than yours... a man can learn something in places that he never imagined.... 

        • Juan Manuel Lynch on

          Well maybe you should try to do it by yourself and not wait to someone tell you how to, then if you dont find the way to do it you can ask for a tutorial. Probably making the effort will teach you more than someone telling you, but sharing knowledge is also nice :)

        • Quick tips or pointers I can understand being asked, or perhaps some general insights to the workflow. 
          EG, what settings are the glare, or how did you come to the lighting setup, etc.But a tutorial (generally implying step-by-step) is very different thing which seems to be asked from every decent piece shown on here BN lately. Of course we all love tutorials but this is usually an unrealistic time consuming ask where the artist may have to recreate the file to show the process.

          I would say dissect the elements as much as you can and ask around for some specific tips on those you can't quite wrap your head around.

  1. mmmm..... although I agree it's nicely done (and I wouldn't be able to do it this good), if you watch the HD version full-screen, there is still quite a bit of noise there. For example at 0:07 both the diamond and its reflection in the ring are showing noise. I would expect 1000 samples to be enough, but not sure if it's only a Cycles problem... anyone?

    Anyhow... good job overall !

    •  dispersion is extremely slow.
      I'm not quite sure who he does it in here but if he does the standard technique, you have to split up the light into multiple colors, assign different IoRs per color and then recombine them.
      This means, instead of a single refraction series, you need to calculate per color. Refraction as-is is already among the slower things. Multiply the time per color you are using and you get how many samples you need, compared to what you'd usually need.
      Additionally, diamonds do their amazing color firework because of quite high refractive indices, combines with a special cut to maximize internal reflection.
      This greater internal distance the light paths have to take causes a much stronger split of the colors.
      However, it also means, light takes a lot longer to get out of the diamond, which effectively increases rendertime and drops the number of rays that actually reach the camera. (Or, since raytracers usually do it the other way round, the lightsource)

      Bidirectional Monte Carlo raytracing could help this. Images in situations like that tend to converge a lot faster compared to PathTracing which is currently used.

        •  @6185049bae79d98aa488ae0125d3588b:disqus & @facebook-1600835418:disqus
          Thanks for the info, really informative.
          If you do a split per color, woaw... that would mean a lot of samples...!
          I noticed LuxRender seems to do refractions more nicely, but I wasn't sure if Cycles would be comparable. Guess not yet.
          Maybe noise-removal could work based on color/area, like in AAfx, but would seem like cheating to me...

  2. Actually, with Luxrender I believe you dont need to fake dispersion. Luxrender does scientifically based rendering, and it's one of the things it can do for you. Then you only need to do the modelling and turn it on in the settings. (Rendering dispersion takes extra time so it's turned off by default.)

  3. Christos Georgakas on

    The intro with the blur was really fiting! but what's with the glare! that is so 80's no ?

    • Kiril Viktorov on

      I know. It's my mistake. I just experimented with post-production of blender. It is my first work in blender. =)

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