Special and visual effects are great, but unless you're a skilled SFX artist or post magician, they tend to be pretty spendy. If you're gearing up to work on a film that calls for characters of varying sizes (or just really into The Lord of the Rings and hobbits), there is an inexpensive alternative to CGI. This tutorial by Ben Lucas of Tuts+ will show you one method the TLOTR filmmakers used to make the towering wizard Gandalf look so much bigger than his little hobbit friend Frodo -- a practical effect that uses forced perspective to sell the illusion.
According to Lucas, TLOTR used four different methods to create the "Hobbit-sized illusion": compositing using green screens, big rigs, stunt doubles, and finally, forced perspective. If you're unfamiliar with this technique, it's essentially an optical illusion that makes things appear closer, farther, bigger, or smaller than they actually are -- like all of the pictures tourists take of their buddies pushing over the Leaning Tower of Pisa.
One great thing about Lucas' video, is that it not only shows you how to set up one of the most important parts of the forced perspective illusion, a split rig (two sets with different sized objects), but it also breaks down the mathematical equation that helps with staging your characters correctly. Lucas explains this further:
The mechanics of this video are geared toward getting the 1:1.3 ratio that is specific to hobbits. However, if you are looking to create any smaller mythical people, figure out how small specifically you are trying to make them, and you can calculate the new camera to subject distances required. Half height? Multiply the human distance by .5 or the hobbit distance by 1.5.
Check out the video below:
It takes a lot of skill to pull off forced perspective, so simply plopping your characters down on either end of a table isn't going to cut it. The split rig helps to sell the effect, but like the video illustrates, you have to pay close attention to eyeline, as well as your depth of field. It'd also be wise to be aware of lighting -- making sure that it falls naturally on your scene, instead of giving away the illusion. Of course, there's more than one way to achieve this effect, but anything that can save both time and money is a definite boon to your production -- not to mention the awesome feeling of pulling off practical effects!
Have you ever tried using forced perspective on your films? What kinds of problems did you run into? What are some tips you could share? Let us know in the comments.
[via Filmmaker IQ]