Monday, January 23, 2017

The Death Star and the Final Trench Run

Star Wars fans pride themselves on knowing each and every detail from the original trilogy. But there’s one little detail from “Star Wars” (1977) that might surprise a lot of fans, and the reality of this detail is different than our collective head canon.

At the end of the original film, Rebel ships fly along the Death Star trench in an attempt to blow up the space station. Look at the photo of the Death Star at the top of this post: can you point to the trench that Luke and the Rebels flew down to fire upon the exhaust port that would ultimately destroy the space station?

Nearly everybody points at the equatorial trench of the Death Star. I asked dozens of die-hard fans, including many co-workers at Industrial Light & Magic, and nearly every single person pointed to the equatorial trench. If you asked me, I would also have said the equatorial trench.

In fact, this came up during ILM “Rogue One” dailies one day. Computer Graphics Supervisor Vick Schutz and Visual Effects Supervisor John Knoll were chatting about the details of our computer graphics version of the Death Star, and Knoll casually remarked that the trench run in “Star Wars” is a longitudinal line on the Death Star (meaning, a north-south trench).

Most of us in the room were dumbfounded. “What did he say?”

Of course, it all makes sense if you think about it for even a minute. 

The equatorial trench is where the major hangar bays are located on the Death Star. The hangar bays are depicted in this sequence from “Star Wars”, when the tractor beam locks onto the Millennium Falcon. The equatorial trench is large enough to house multiple hangar bays stacked vertically. 

Now, contrast this with the final trench run; the trench is barely large enough for three small fighters to fly down, side-by-side.

So, we now realize that the trench with the Death Star’s exhaust port weakness is not located at the equator since the equatorial trench is several times wider than the final trench, but how do we know that it’s a vertical, longitudinal trench. Why couldn’t it be a different latitudinal trench, parallel to the equator? Or, perhaps the equatorial trench narrows on the ‘far’ side of the Death Star, the side of the Death Star we never see?

Well, it’s a longitudinal north-south trench because the movie literally showed us.

detail of the Rebel briefing sequence, led by General Dodanna

The scene of General Dodonna briefing the Rebel troops contains some computer graphics displayed at the front of the room. As Dodonna describes the challenges ahead, the audience can see quite clearly that the trench that contains the exhaust port is perpendicular to the equator. It was there the whole time.

Why have so many of us been confused for so many years? I have a few ideas on that.

There are only two prominent geometric features on the Death Star: its dish and its equator (a trench). Later in the film, we see a third bit of geometry, the final trench. Our brains want to connect this new trench with something we've seen before, and because of their similarities, and the simplicity of that connection, it’s not a big leap for us to (incorrectly) deduce the two trenches are one and the same.

Secondly, consider this shot, which takes place early in the battle sequence, of the X-wings preparing to draw Imperial fire:

Look at how this shot is composed; the two lead X-wings are banking right and swerving, almost as if they are about to travel down the length of the equatorial trench, which is prominently featured in the shot and sits directly behind the lead ships. In reality, the X-wings start their attack run down the trench much later in the sequence, but this shot is visually striking, and subtly (and wrongly) suggests the attack run takes place down the equatorial trench.

Combine this with this POV (point-of-view) shot, used twice in the film, depicting a Rebel fighter’s initial descent into the final trench...

...and our brains once again combine these two thoughts. Both shots feature a fighter diving in the same screen direction to (apparently) travel down a trench. We incorrectly conflated these two shots, combining them into a single location.

Don't feel badly if you thought the final trench was the equator. Heck, even Legoland got it wrong in its giant Death Star lego build.

Legoland in Carlsbad, CA. Photo by Todd Vaziri, November 2016
(Live Photo from iPhone 6, GIF'd with Google's Motion Stills iOS app)

Here’s one more bit of trivia about the geometry of the Death Star. Did you notice anything a little strange about the animated Death Star plans that R2-D2 successfully delivered to the Rebels?

The weapons array (the dish) is centered on the equator! Of course, the Death Star we see in the film has the array clearly in its northern hemisphere. Why is there a discrepancy?

Larry Cuba was tasked with creating the computer graphics for the film, depicting the stolen Imperial plans. He was given a single matte painting to base his graphics upon (shown above). This early design of the Death Star had its equatorial trench bisecting the dish array. Cuba had already started animating when director George Lucas and Industrial Light & Magic made a design change to the Death Star, moving the array to the northern hemisphere. There simply wasn't enough time to change Cuba’s already-in-progress graphics to reflect the design change, due to the massive complexity of the creation of the computer animation; the graphics based on the original Death Star design was projected in the General Dodonna scene for the final film.

update: Larry Cuba reached out to me to correct and add clarity to the timeline of events. Cuba says, "I don't know *when* in the course of the production the decision was made to change the design, but I wasn't notified of it. I don't think it would have been that difficult to change [the graphics]." To be clear, Cuba's completed graphics were rear-projected on-set during first unit shooting. At some point after that scene was filmed, unbeknownst to Cuba, the design change to the Death Star array took place. Subsequently, all of the visual effects models and matte paintings of the Death Star (with the new placement of the dish) were created at Industrial Light & Magic in Van Nuys, California, with the "new" location of the array.

Cuba also reminded me of this cool detail he added to the animation of the graphics. "You'll notice that after the Death Star appears in the animation, it rotates toward you to show the north pole, supposedly the location of the exhaust port, before rotating back to zoom in on the point the pilots were to enter the trench much further south for their approach." I love the method Cuba took to help tell the story here: he's using the rotation of the camera to first indicate the location of the port, then the location of the best place to enter the trench. 

We joked in “Rogue One” dailies that the Stardust file Jyn stole actually contained every major version of the plans of the Death Star, including an early version with the array bisecting the equator (but still containing Galen Erso’s exhaust port vulnerability), and at the Rebel briefing in “Star Wars”, General Dodonna just happened to project one of those early versions to the troops. Head canon!

Here are some terrific resources online discussing Larry Cuba’s computer graphics on the film:

• “Making of the Computer Graphics for STAR WARS”

• Animating the Death Star Trench, from Fantastic Films


The original Atari Star Wars arcade game also strongly implies the equatorial trench is where the final run takes place. Thanks, "DoctorMemory".

On January 25, I decided to turn off comments for this article.