Stereo video rig

Stereo imaging

Stereoscopic imaging uses two cameras (either still or moving image) to view a scene from two slightly different vantage points. This is essentially how our eyes work; they are separated by about 60mm, and therefore receive two different views. The brain then fuses these together, with the differences in the images being perceived as depth information.

This can be achieved photographically be placing two cameras together such that their lens axes are separated by about 60mm. For moving subjects, the cameras are triggered simultaneously. For static subjects, this is not essential and, indeed, a single camera which is moved between exposures may be used instead. There must also be some means for ensuring that, when viewing the resulting images, each eye sees only the appropriate image of the stereo pair.

The camera separation may be varied; for "normal" subjects, the lens separation is around 60mm or so. In hyperstereo, a large camera base is used, and is applied to distant subjects for which the normal base is not sufficient for supplying depth cues. In hypostereo, a small camera base is employed for imaging close subjects.

SAPAC equipment

Still cameras: two Sony DSC-V3 cameras.
Video cameras: two Sony HC-21 mini-DV cameras (PAL, interlaced).
Synchronising unit: Ledametrix LANC Shepherd Pro.
Mounting: various in-house mounting bars, with Manfrotto tripod and 128RC video head.
Editing: Adobe Premiere Pro for editing video.
Viewing: via projection in the SAPAC VisLab (the Infitec system); projection or shutter-glasses in the SAVRC; shutter-glasses on our desk-top visualisation workstations (under development as of 3/2006); free-viewing on our lenticular vertical-interlaced monitor. For video files, we use Stereoscopic Player.
Delivery: stereo stills and video files can be provided in a variety of formats, e.g. side-by-side, above-and-below, as separate files, anaglyphs. For use outside SAPAC's facilities, the end-user must provide viewing hardware. SAPAC will endeavour to provide an output format suited to the user's hardware and software.

SAPAC Services

Stills: normal and hyperstereo imaging; ambient lighting or with camera flash; alignment and conversion to appropriate output format.
Video: normal and hyperstereo imaging; ambient lighting only; synchronising, alignment and conversion to appropriate output format. Limited audio editing (e.g. over-dubbing) can be arranged.
Editing: cropping, cleaning, alignment and ouput conversion of digital-format stereo pairs, e.g. scanned archival stereographic images, etc. Synchronisation, alignment and output conversion of stereo video files (from a suitable digital video format).
Viewing: use of SAPAC VisLab or SAVRC for viewing stereographic content.

Anaglyph still image galleries

A selection of various stereo pairs obtained with the Sony DSC-V3 cameras can be viewed as red-cyan anaglyph images. The main page for these galleries is here.

Status

August 2006 : The basic techniques of stereoscopic stills and video production have been examined, and such content can satisfactorily be developed. General experiments with normal, hyper- and hypo-stereo separations are continuing in order that many types of subject may be dealt with.
July 2007 : work with a pair of Canon XH-G1 HD video cameras will begin shortly.