View Full Version : Green screening a spray of tiny clear objects


Steven Hoffman
July 24th, 2010, 11:41 AM
I'm trying to make it look like clear crystals are shooting out of a persons ear.

I'm thinking that using a green screen and a hose full of plastic crystals that we can get them shooting out in the desired way, however, I'm not sure if its possible to film them from a distance and not have them completely key out when its time to remove the background.

I'm then thinking of simply using the footage, keyed out, over footage of the subject.

I know its an odd request, but does anyone have any ideas I can try? Is green screen a bad idea for something like this?

Panasonic AG-HVX 200
Green screen,
3 Tota Omni's, and a pro
and around $100 spending money.

Shaun Roemich
July 24th, 2010, 11:49 AM
IF this is possible, I'm going to suggest that a STRONG backlight might be the "key". (Pardon the pun...)

Probably easier to try and find pre-keyed material or CG it yourself...

Dano Motley
July 24th, 2010, 01:20 PM
go to digital juice dot com and check their compositers tool kit. might already have it done for you?

Dano

Dean Sensui
July 24th, 2010, 02:09 PM
Primatte can do this. I've keyed transparent plastic packaging -- the kind that requires a chain saw to open after you bought something like a CF card or similar.

There are several things that need to be carefully set up. One is the green screen -- expose it at 50 IRE. Another is the camera -- do not use any odd matrix setups. You'll want that green to be green. Try to eliminate any sharpening that will create edge artifacts. And shoot only in progressive mode, not interlaced. Of course it should be in 1080 p30 HD.

The HVX can shoot a nice key. I've done it before.

As Shaun suggested, you can use a backlight. While Primatte can key without the backlight, using a point source as a backlight will get the crystals to sparkle. Be aware that any lighting you use on the crystals will also have to make sense in your master shot or it'll look out of place.

OR you can use particle effects if you have After Effects. The advantage is that you can animate it to do almost anything you want, and you can play around with it until you acheive the effect you're looking for.

Bill Davis
July 25th, 2010, 01:56 AM
Another vote for After Effects or Apple's Motion.

Both do particle effects so easily that you should be able to get something with an alpha channel that you can composite over an existing shot in short order.