R&D: stereoscopy rig

workshop / tools

Stereoscopy Rig for NEE Pilot

We needed a capture, monitoring and display solution for stereoscopic HD video (1080 lines).

There are several semi-professional capture systems available (twin-lens camcorders) and also industry standard solutions (mirror boxes for mounting two camcorders eg. Sony EX1). Stereoscopic monitors can be attached to the shooting rigs; for the edit suite, monitoring solutions include full HD (1920 x 1080) twin-LCD displays incorporating semi-silvered mirrors.

A complete semi-pro or industry standard capture and monitoring system would cost approximately EUR 10,000 minimum (or much more, depending on specifications).

We found a way to get close to industry standard quality and flexibility levels with a DIY rig using a pair of 1920x1080i memory card camcorders, an external LANC sync unit, and an inexpensive passive 3D monitor designed for stereoscopic computer gaming.  

• 2 x Sony TG-V7E camcorders (1920x1080 @ 50i, AVCHD compression, 16GB memory, zoom lenses with wide-angle attachments, manual parameter adjustment).
• ste-fra LANC remote: this unit triggers recording on a pair of cameras, indicates the sync mismatch (from 0,1 to 3 ms), and allows synchronised zooming. It does not actually sync the cameras (like GENLOCK) but it does mean that they can be reliably triggered almost simultaneously, within 1/10 of a frame of each other.
• custom stereo bar: mount for a pair of cameras and accessories; allows the interocular distance and lens convergence to be adjusted (lacks scales and precision of more expensive solutions, but costs only 10% of the price).
• Manfrotto Fig Rig: inexpensive alternative to a steadycam, allows the pair of cameras to be handheld steadily together with the remote and an audio recorder.   
• Zalman 240W stereoscopic 24" monitor. For the edit suite. Works with inexpensive passive polarised glasses. Display resolution is 1920x540 for each eye, so loses half vertical resolution. Vertical viewing angle is very narrow.  
• Audio recorder and mic, mounted on stereo bar/Fig Rig.

Edit Suite:
AVCHD files from the camcorders are transcoded to Apple Pro Res 422 and then can be edited and formatted for various kinds of stereoscopic display and projection systems.

Our system has a few weaknesses:
No live stereoscopic monitoring, and monitoring/display in the edit suite has half vertical resolution per eye.  
No repeatable, precision alignment of cameras (but we're working on a fix).
No remote control over manual focus.

report by mukul patel, 2010/07/14