"In a development that will revolutionize - and greatly simplify - the production of live-action stereoscopic 3D video, PassmoreLab, in cooperation with Atlanta-based 3dh Communications, has patented a landmark system for the precise alignment of multiple cameras, as well as time synchronization of multiple stereo channels. Continuing its advancement of technology for 3D imaging, the southern California-based company has addressed the problems associated with the time-consuming camera alignment process, and created a technical solution that will significantly reduce production time and expense.
The new, patented system utilizes a special target placed in front of the multiple cameras - essentially a digital "slate" - to mark the beginning of a shot. This digital cue is then applied during post-production through the application of proprietary software, which analyzes the target and automatically performs precise vertical and rotational alignment, thus eliminating visual conflicts between the multiple stereo channels. Significantly, the system can be used in conjunction with large camera arrays, such as the prototype 10-camera array recently developed by PassmoreLab, as well as simple stereo configurations.
To fully grasp the importance and potential benefit of this new technology, consider that using standard processes, in order to obtain accurate stereo alignment it is required that cameras be placed on precision mechanisms with all alignments being done manually, often demanding numerous incremental adjustments to achieve acceptable results. Understandably, this is a slow and tedious process that wastes time and resources. By contrast, using the new system it is now possible to simply place two cameras side-by-side on a table, complete an image capture, and in post automatically perform precise vertical and rotational alignment for superb results. In addition, if the interocular distance between the cameras is inappropriate for the subject, the software can apply a horizontal-offset bias for the scene - essentially allowing the user to adjust the apparent location of the screen plane - that will assist in making the video output more accurate and visually pleasing to the eye. Again, this was a problem that previously had to be corrected through manual camera adjustments and tedious trial and error. This should be great news to the entertainment and advertising industries, which now have a technology that can considerably lower production costs over time.
Another groundbreaking element of the patented system is in its application to specialized filming techniques, such as the use of helmet-mounted cameras and other camera configurations required for challenging location-shooting situations. Here, the difficulty arises in cueing the exact initiation of image capture between multiple cameras, as well as maintaining precise alignment in space. The new system utilizes a photographic flash unit, which is directed into the cameras' optics and triggered at the start of a shot. In post, the software uses this visual cue to time-synch the multiple channels, while also performing vertical and rotational alignment of the channels. It is now possible to essentially place multiple cameras in relative alignment and pointed at a subject, start each of them independently, and simply trigger a flash when the shot is ready to start. In post, everything is then precisely aligned in time and space. As noted previously, the system is applicable to bigger multi-camera arrays, accomplishing automatic alignment between large numbers of video channels. This makes it particularly suitable for the types of arrays needed to produce content for auto-stereoscopic displays, where up to 10 video channels may be used.
A further benefit of the new system is that it allows for the use of inexpensive, lower-end video cameras, which may be better suited for difficult or potentially damaging shooting situations or locations. Such applications would be extreme action sports, auto racing, skydiving, surfing, underwater shooting, or anywhere that the risk to high-end equipment would be prohibitive."
Source: Stereoscopy
