In 1968 a film was released that would change the sci-fi movie landscape forever. ‘2001: A Space Odyssey’ is still considered the pinnacle of science fiction story telling and visual design.
When the film was being produced the human race had yet to land on the moon let alone live and work in space for long periods. The science fiction films released around the same time were all of a B movie quality. ‘2001’ treated its viewers with upmost respect and its visual style is anything but B movie!
The films climax sees astronaut David Bowman travel through the aptly named ‘Star Gate’ to another time and space. When posed with creating the visuals for this scene visual effects genius Douglas Trumbull turned to a technique that had been used in many films before – Slit Scan. Although John Whitney has often been credited with pioneering the Slit Scan effect (in films like Alfred Hitchcock’s ‘Vertigo’) it is Trumbull who refined the technique. Trumbull’s real brilliance was how he built and ran his Slit Scan machine.
Trumbull’s Slit Scan rig consisted of a camera on a track that could move forwards and backwards, a slit about 4’ high and illuminated artwork on a panel behind the slit. The synchronous motors he used meant the camera, slit and artwork could all be programmed to run simultaneously. This meant that he could do endless testing and repeat shots with super accuracy. He could also layer up the exposures for maximum effect, rewinding the film in the camera and exposing another piece of artwork.
The shutter on the camera was open as the camera moved towards or away from the slit on the track. The shutter would then close at the end of the move, the camera would move back to the start position and the artworks start position was moved slightly. The whole process would then be repeated for the next frame.
After watching ‘2001′ at The Prince Charles Cinema in London I felt inspired to try and understand more about the Slit Scan effect and recreate it in a digital age. Using the 3D environment inside Foundry’s NukeX I felt I would be able to build a virtual version of Trumbull’s Slit Scan rig. I used a 3d camera and 3d cards to create the other parts of the setup.
- The size of the slit.
- The amount of movement in the start position of the artwork between each exposure.
- The speed of camera move.
The first version I created was good but was more like a 1980’s video effect, a little like a ‘howl around’ (the effect used in the opening credits of BBC’s Dr Who). The problem was that the artworks start position was not being adjusted between each exposure. By moving the artworks start position ever so slightly between exposures the illusion of movement is given. Thanks to Lev for this insight.
Each exposure in my setup was made up of 100 frames. One disadvantage of Nuke’s 3D camera is that you can not leave the shutter open as Trumbull would have done. Everything must be done in frames. I used the TimeEcho node to mimic the long exposure time. After that a FrameHold made sure I’m only rendering the fully ‘exposed’ frame.
Next was how to set this up so it would render automatically. Lev and I tested setting the curves of the camera and artwork movement to loop automatically but this was very fiddly to control (and adjust later) and never worked perfectly. Setting the loop even one frame out meant that the slit would slowly move out of sync with the camera and chunks of the image would be lost.
In the end I used Python to adjust the start position of the artwork after each frame was rendered. In the Write node Python commands can be set to run ‘after each frame’ is rendered for example. After each frame was rendered a TransformGeo node moved the artwork 3D card in ’X’ very slightly. The next frame would then be rendered, again made up of the 100 frames but with a slightly new start position on the artwork.
After the frames were rendered I brought them back in to Nuke and rendered out as a QT, added a flopped version on the other side of the screen, some blurs, retimes and glows to help with the effect.
This project has improved my understanding of how to loop curves and how the generate keys function can be super useful. It’s also helped me see how useful setting Python commands in the Write node can be.
This was a great project to understand a process not used these days. As with any project of this nature, delving in to retro techniques has given me even more admiration for the technicians that worked on this effect. I’m sure it was a lot of trial and error but once they cracked it they really cracked it. The Star Gate sequence still stands up today and along with the music really does transport Bowman (and the audience!) to another time and space.
Final Nuke Script – starGate_v1_to_publish.nk
Python to advance slit after each frame is rendered – afterEachFame_advanceSlitScan.py
Doctor Who Slit Scan and Howlaround
Douglas Trumbull – Slit Scan Motion Picture Photography – 2009 SOC Technical Achievement Award
The History and Science of the Slit Scan Effect used in Stanley Kubrick’s 2001: A Space Odyssey
Cinefex #85 (April 2001 of Course!) – 2001: A Space Odyssey | A Time Capsule
Many thanks to Lev Kolobov, Zissis Papatzikis, Angus Bickerton, Steve Begg, Matt Tinsley and Ed Plant for their help with this project.
2 thoughts on “Recreating 2001’s Slit Scan Effect in Nuke’s 3D System”
Nice work, Jack!
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Thanks Andy. This was a fun project to work on. I wish I could have seen the rig Douglas Trumbull used on 2001. I hope your well.