Author Topic: Gems Render (reflection & refractions)  (Read 38547 times)

0 Members and 1 Guest are viewing this topic.

Offline MrZmey

Gems Render (reflection & refractions)
« on: June 07, 2011, 01:44:47 pm »

Any one know any good lessons, or video about "how to render a realistic gems"?

I did some renders but it looks with no refracions.. looks flat..

- Thank You!

Offline Speedster

Re: Gems Render (reflection & refractions)
« Reply #1 on: June 07, 2011, 02:04:04 pm »
Last week Jeff did a long webinar focused on gems and jewelry.  There were some technical glitches with the broadcast, which is likely why it is not yet posted in the webinar listing on the forum.  I'm sure it will be as soon as it's edited, and I'm really looking forward to downloading it, as a client meeting cut my webinar time in half, so I missed the best parts.  It's excellent and well worth waiting for!

For starters, increase your Gamma setting on the Realtime Tab to about 2.0 to 2.2, and kick up your ray bounces to 16-20. Duplicate the ray bounce number on the render tab as well. These, along with carefully choosing an HDR, will get you well on your way.

Bill G

Offline JeffM

Re: Gems Render (reflection & refractions)
« Reply #2 on: June 07, 2011, 05:48:28 pm »
Brian presented last week's webinar ;)

We will get that up on the site very soon.

Great tips, thanks Speedster!

Offline MrZmey

Re: Gems Render (reflection & refractions)
« Reply #3 on: June 07, 2011, 11:05:02 pm »
Gamma 2.2 / Ray bounces 16
and this is not what I need... (

- Thank You for try)

Offline MrZmey

Re: Gems Render (reflection & refractions)
« Reply #4 on: June 07, 2011, 11:54:16 pm »
need something like this.. with reflections..

Offline Ed

Re: Gems Render (reflection & refractions)
« Reply #5 on: June 10, 2011, 09:09:50 am »
Getting good diamond renders is not always as automatic as it is with other materials.  There is a lot of interaction between the material settings, the HDR used, and the environment settings.  

Plan to experiment a lot, especially with selecting the right HDR.  Look for HDRs that have good contrast with both light & dark areas.  HDRs with less dramatic lighting (like "Startup") won't do as well with stones.

My settings for the top render are:

Large diamond material:
IOR 2.417
Abbe number 20

Brightness 1.0
Gamma 1.2

Brightness 1.3
Gamma 1.0

Sometimes it is difficult to find an environment setting that works well for both the stones and other objects in the same scene.  For example, lighting that is ideal for a diamond may blow out the metal ring shank (same issue occurs with photography). To resolve this, the bottom image was made from two renders, layered in Photoshop.  The bottom layer was a render with the environment settings optimized for the stones, while the top layer was a render optimized for the reflections in the ring shanks.  Using a round eraser, I removed the stones in the top layer to reveal the stones in the bottom layer.

Finally, make sure your stones don't touch or intersect with any other geometry.  The stones in the bottom render are free floating within the ring shanks, with a minimum air gap surrounding them.  If they do intersect, they will pick up qualities of the adjoining material.  I test for this by changing the ring shank material to a red anodized metal - if the diamond turns red also, I know it is touching the metal.

« Last Edit: June 10, 2011, 09:38:18 am by Ed »