Wim Wenders: Flying in Stereo 3D
Wim Wenders’ “Il Volo” (The Flight) tells the story of a group of immigrants who arrived on boats at the coast of Calabria. Shooting with two Vipers and two SI-2Ks required on-location services for both systems provided by Lilliwood and its Munich-based partner Greenpost. Read the behind the scenes story by Thomas Harbers, CEO at Greenpost.
The Viper-material was captured using SONY SRW-1, we then ingested all material to two uncompressed Quicktime-movies per shot. The SI-2K magazines went straight into our SpeedGrade DI workstation, as SpeedGrade can work with the RAW files natively. Mixing these files with Quicktimes for dailies was a breeze as SpeedGrade can manage any mix of resolutions and practically every format within one project.
Being the DIT on this job, I usually would not care about what you see in the viewfinder, you can set things clean and just worry about not clipping your highlights. But the DoP wanted to see “natural colors” even for the preview, so we used SpeedGrade to create some nice .looks for our show that were used from the very beginning to simulate film stock and a basic style.
The challenge was to match the 2 sets of cameras. We created looks to make the SI-2K-material look like the Viper material and one to make the images on our Hyundai 3D LCD look like the Material from the HDCAM-SR played back on a JVC-Broadcast Monitor.
For prepping the Dailies we always used the same kind of procedure, going through a fixed list of steps:
Step 1: Getting l/r in sync
In theory you should never see any temporal offsets between left and right eye, in practice it’s really nice that SpeedGrade has a simple way of taking care of this task.
Step 2 Colorimetry Matching
No two camera sensors are exactly the same. The same goes for two lenses. Even if you use a matched pair, you’ll still have different optical qualities. On top of that, shooting with a mirror rig always presents its own issues. On our P+S rig we had left camera looking through the semitransparent mirror and the right eye camera facing the mirror. The differences in colorimetry and the subtle luma differences have to be matched in grading, which is quite easily done in Speedgrade: When you apply a grading to a clip you can select if you want to have this grading applied to both eyes or only to left or right eye. When you have lenses that differ greatly in vignetting for example, you can even apply a mask to only one eye to straighten that out.
The 2010 release of SpeedGrade which we had available as an early Beta does the colorimetry matching automatically – with very nice results on almost all kind of shots.
Step 3: Geometry Alignment
With a well calibrated rig, this task shouldn’t consume a lot of time. SpeedGrade 2010 does it automatically even, identifying vertical offset, rotation, focal length issues. As it creates a number readout, you can qualify the amount of trouble you create for further work in post. And you can still manipulate each value as everything is just metadata.
These tasks becomes tricky when you need to animate offset values. The mirror-rig from P+S is built with carbon fibre rods which are quite sturdy, but with one Viper camera weighing 5-7 kilos, those rods will bend. Maybe a small fraction of a degree, but that’s enough to give you a few lines of vertical offset in the distance.
As soon as there is a tilt during the shot, the bending of the rods will change over time, giving you different vertical offsets in the beginning and the end of the shot. With animated key frames in the Stereo Panel in SpeedGrade, this is easy to address.
Step 4: Convergence and Handovers
“Il Volo” was shot converged. Therefore we didn’t touch the convergence slider in SpeedGrade once for the dailies. As we got into post, that changed, of course. We used the animated convergence settings in SpeedGrade to create smooth changes along the Z-axis from shot to shot.
For this part in post, I didn’t even have to leave my office to work with the guys at Lilliwood in Bologna: SpeedGrade has remote review capabilities, and Lilliwood runs their own SpeedGrade DI system. We could run remote sessions to discuss the creative aspect of Depth Grading while I was in Munich and they were in their office in Bologna, changing parameters interactively from both ends.
If you ask me about what was most amazing throughout the eight days of shooting from a technicians perspective, it was working with the two SI-2K cameras. As we moved around a lot, sometimes there wasn’t enough time to get the workstation set up for prepping the material the same day. I used my notebook instead to have a quick look at the SI-2K-material. The notebook GPU does not give you full performance for realtime playback, but checking the stereo setup works great.