Optical Printers.

The Anderson- Named after Howard Anderson, who built the printer for use on the Ten Commandements

The L.S. - Named after John Ellis, the camera operator who built the printer by hand.

The Work Horse - Built in 1982 when budgets were tight, with the rationalization this printer would save time and money and pay
back its development.

The Quad - Designed by Richard Edland for The Empire Strikes Back, built as a double printer with four projectors prior to The Return of the Jedi until
the Work Horse was put to use. The lenses are custom designed by ILM to produce an image so sharp and clear that the only limitation to the detail
was the film grain. This and the Work Horse feature computerized control systems. (shown below)

How Optical Printers work.

#1 - A projector shines the front strip of film over the strip before it. (#2)

#2 - This strip of film has the image we are trying to composite into the scene. (TIES, Live Action Footage, etc).

#3 - This lens focuses the elements from strip #1 and #2 to be composited to the final film strip (#4)

#4 - This strip of film already has its own image on it, such as the image of a Matte Painting, motion backgrounds, etc.

#5 - The camera that photographs all the films composited together in the lens's eye. To this camera, the images appear to blend together with
crystal clarity, save for the grain of the film which produces the final illusion of all the elements existing in the same place.
 
 

Preparing for Film.

The Blue Screen Process - Special screens are used to substitute a scene shot with live action or miniatures which will then later be replaced
by matte paintings or other environmental effects. Blue was used mainly for metals and grays, while currently green is more sought after because it
does not conflict with skintone. The blue is "keyed out" which means it is turned transparent so other objects can be composited in its place.

Let's take a look at a basic blue screen set up in which I'll use the example of Chewbacca "magically" joining the
Battle of Geonosis in Attack of the Clones.
 

The original footage of Chewbacca in the falcon set, where only blue panels depict the exterior of the vessel.
 
 

Here the blue has been "keyed out". The gray represents the transparency in the image.
 
 

Here is the background plate we want to composite into the scene.
 
 

Here is the final composite with a slight blurr applied the background and light adjustments of Chewbacca joining the impossible battle!
 
 

Basic Set Construction - The bare minimum to film a scene which usually consists of no more then live actors, a few foreground elements, and blue/green
screens scattered throughout, whose positions are tracked and numbered for later composited elements such as CGI or other visual effects.

In this case, the blue screen is where Leia, Luke, and the droids stand gazing to a swirling galaxy which is later composited once the blue screen is keyed out.
There is nothing beyond the basic setup of the window on the actual stage, what the camera cannot see, does not matter in the capture of the shot.

Miniatures- Used to simulate larger scale objects, built on smaller scales where a full sized prop cannot be attained or cannot function the
way the director wishes it to. Miniatures may also be submerged or rigged with pyrotechnics for explosion sequences and fitted with internal
lights to simulate lighting effects.

Props and Live Action - A prop is anything that is not nailed down on a set, which can range from weapons, equipment, boxes, clothing,
to single elements like door frames and or wall panels. Live action is live actors filmed against the blue/green screen or miniature effects.
 

Keying out the Blue Screen.

Removing Blue Screen - This is also known as "keying out" the blue or green elements from shot footage. Currently this is done digitally with compositing
programs such as After Effects, Combustion, Commotion, and Premiere, or with plug ins like DV Matte or Ultimatte. However, we will say for the sake of
demonstration that these methods are not avaible to key out and composite footage of Luke and Leia flying at great speeds through the Forest of Endor
in Return of the Jedi.

Let us label the above images as Figures #1, #2, #3, #4, and #5.

Figure #1 - Carrie Fisher and Mark Hammil are filmed against the blue screen, with fans blowing on them to simulate
flying at great speeds. (1000 miles per hour)

Figure #2 - A backwards walk with a glidecam through the woods shoots only 1 frame every few seconds. When played back on screen at
24 FPS, the pace speeds up by 5000%.

Figure #3 - Remember those hand cut mattes in the rotoscoping section? Same thing applies here, which we will call the Cover Matte which consists
of a Garbage Matte (grey) traveling over the footage, staying stable over most of the screen while the Traveling Matte (white) follows the
movement of the two actors on the bike. The black area actually covers most of the blue screen as its own Matte.

Figure #4 - From the Cover Matte, a final Holdout Matte is created, being the silhouette of the actors and the bike. The area that the silhouette
covers will keep that section of the film unexposed when Endor (figure #2) is rephotographed next to it. The space can then be filled in with the
image of Luke and Leia that the Cover Matte will let us create.

Figure #5 - The composited frame with Endor replacing the blue screen completely. Currently as stated before, we can just drop in our footage, run
a plug in or do a few actions and avoid the TEDIOUS nature of the matte creation process above, then plunk our background plates into place, render,
and enjoy the work! Thank your lucky stars we now live in a age where the frustration of keying has been limited.

Now view the exciting, high speed footage of the Speeder Bike chase from Return of the Jedi by clicking here.
 
 

Creating Optical Magic.

Background to Foreground - When compositing a scene, the elements must be shot from the background to the foreground so that every element
such as ship exhaust and other methods are placed with the proper illusion of depth and perspective. This however can change if such elements do not
directly overlap eachother, such as smaller ships composited in the extreme background.

Photographic Mattes - As shown in the Speeder Bike demonstration, a main element is seperared from its background or vice versa.

Pin Registration - In order for every composite to be absolutely flawless in the layered exposure process, special pins keep the composited perfectly
aligned so that nothing is shifted out of place, which can be either seperate mechanical devices, or inside the camera's themselves.

There can be an unlimited amount of exposures in a single shot, this is known as Multiple Exposures or "Layering" the shot. A perfect example is the
flock of TIE fighters swarming like a hornets nest at the Rebel Forces in Return of the Jedi.

In order of composite..

1. Background/Space plate.
2. Middleground/Endor Plate
3. Foreground/Mon Calamari Cruiser
4. Death Star II
5. Rotoscoped Superlaser Beam
6. Reflected light on Mon Calamari Cruiser.
7. X-Wing
8. A-Wing
9. Rebel Transport
10. Secondary Rebel Transport
11. Distant Fighters
12. Very Distant Fighters

You can view the final footage of a extensive, 125+ exposure composite sequence of a swarm of TIES here.