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stevegraymusic
10-13-2015, 09:06 AM
I'm working on a short (10 seconds) animation of a girl dancing wearing a prom dress and tiara with rhinestones on them and I was looking for a way to simulate the rhinestones sparkling in the light.

I thought about making each gem using the gem tool but the rendering time is crazy for just one gem. 50 gems would take forever.
I also thought about just making the gems and giving them a mirror surface and letting the mirrors reflect the light and then adding pin spots to specific area of the gems in order to fake "sparkling".

Does anyone have any ideas on how to simulate this effect without weeks of rendering time?

Thanks!

pinkmouse
10-13-2015, 09:15 AM
I'd try very basic geometry, a perhaps a cube with a shrunken top, with a mirror surface as you suggest. As for lighting, you could try with a few lights, (perhaps set to light the rhinestones only) or create a few luminous boxes spread around the character and set as invisible to the camera.

stevegraymusic
10-13-2015, 09:27 AM
@pinkmouse - Thank you!! I will give it a try!!

jeric_synergy
10-13-2015, 10:35 AM
Realistically, how visible are the gemstones? If they are tiny points, don't bother modeling them. At most, a 'radar-reflector' mesh will give you reflections, or tiny mirrored spheres.

stevegraymusic
10-13-2015, 10:57 AM
Realistically, how visible are the gemstones? If they are tiny points, don't bother modeling them. At most, a 'radar-reflector' mesh will give you reflections, or tiny mirrored spheres.

Thanks jeric_synergy for the input...

What is a radar reflector mesh?

About the size...the gems in the tiara are tiny but the gems on the dress are quite a bit larger...they are arranged in a band of jewels on the waist band of the dress and they are much more visible.

spherical
10-13-2015, 01:54 PM
Mirrored spheres won't give any sparkle. They'll reflect constantly, instead of winking on and off. I would create a displaced surface using Turbulence or such, in order to generate the number of reflective surfaces at various angles to yield as many reflective vectors as possible in a given area. Gems reflect many rays in a general direction all at once or in quick succession. A simple chamfered cube won't have as much life. IOW, if you're going to fake it, you have to somehow approach the number of reflections that a real cut gemstone would, due to TIR within the shape.

pinkmouse
10-13-2015, 02:39 PM
Take heed, spherical knows reflections! :D

spherical
10-13-2015, 03:00 PM
You made my day. :)

Greenlaw
10-13-2015, 03:31 PM
Personally, I would do this as a post effect in compositing and be done with it. This approach take minutes as opposed to hours.

Here's one method: render a matte for the sequined object and then in AE use a filter like TrapeCode StarGlow. I don't have an example handy but here's the link to the tool:

https://www.redgiant.com/products/trapcode-starglow/

There are other similar filters for AE and for other compositing programs of course. You can also combine directional blurs and glows to achieve similar effects.

In Fusion, for example, you could use the Highlight node. You just need to isolate the hottest points in the render and have the the tool work its magic on those points. If you need to, you can isolate the resgions very tightly using Levels. (Rendering to float space should help if you're going to really fuss over it).

If the object needs to shimmer while sitting still, multiply an animated fractal patten over the mask. This will cause the filter to sparkle and shimmer. You probably don't want to do that for moving objects though--it's likely to shimmer too erratically.

Hope this helps.

G.

jeric_synergy
10-13-2015, 05:24 PM
Mirrored spheres won't give any sparkle.
Sadly, my language has been corrupted by 3d modeling programs; what I meant was a FACETED spheroid, like a Tesselation sphere at setting "1".

+: dwburman did a whole video series on making sparkles in LW, you can check it out on Liberty3d (http://liberty3d.com).

stevegraymusic
10-14-2015, 08:03 PM
Thanks guys!! I really appreciate all of the suggestions! No other forum replies this quickly or efficiently!