We get to see a lot of computer generated special effects breakdowns these days, but nothing like this. Today I came across a video showing the before and after shots from Steven Spielberg‘s Jurassic Park. While the film is known as one of the first blockbuster films to extensively employ computer generated effects, there are actually only 15 minutes of dinosaurs in the film: 9 minutes of which are Stan Winston’s animatronics, and only 6 minutes of ILM’s computer animated versions. But those six minutes are quite impressive for a film released over 20 years ago (1993). After the jump you can watch a six minute video which breaks down the Jurassic Park special effects showing how the computer generated dinosaurs were added to shots in post production.

Here is a bit of backstory from IMDB:

Steven Spielberg didn’t want people to be constantly reminded that what they’re seeing is CGI, but real, full-blooded dinosaurs, starting with the Brachiosaur scene, where Spielberg was keen on the dinosaur interacting with the background, and would offer suggestions to the animators on how to make it better. The second scene done in that same vein was the Gallimimus scene, which made use of 25 animated individual Gallimimuses. Geometric shapes represented them initially and were choreographed onto the scene. Spielberg needed complete freedom to convey the energy of the scene, so worked with Dennis Muren to shoot it, because he wanted to move the camera and not lock it down everytime a Gallimimus came into frame. The scene was shot gradually with Sam Neill, Joseph Mazzello and Ariana Richards running through a field by themselves. A grid was placed over the ground as a frame to chart the movement of the camera by computer, using what looked like golf balls whenever an actor looked somewhere. The dinosaurs were than added later.

The T-Rex chasing the Jeep was the most difficult scene to animate. Steve ‘Spaz’ Williams had to do research because there’s no frame of reference for a running animal of that size; it took two months to figure out how to get it to run, for instance. He would run the sequence backwards to see all the mistakes. They were also able to use the computer to add little details to authenticate the scene, e.g. the T-Rex running through puddles of water and leaving splashes, etc. The splashing was filmed individually and then the computer added it to the T-Rex’s footsteps.