The idea behind making panoramas in the “slit-scan” fashion is this: if you’re in a moving vehicle and want to record the scenery passing by as a long panoramic photograph – would this be possible by capturing the scene with a video camera and by stitching the video frames together as a static two-dimensional image?
In practice this can take place with a special slit-scan camera that records a narrow vertical line of pixels to add it to the panorama in real time, or with with a computer that does the same based on video footage.
I call these ‘Travel Panoramas’, both because they can only be formed by travelling, and as a reminiscence of the moving panoramas of the 19th century; long painted panorama canvases that were rolled in front of the viewer to create an illusion of travel.
Conventional panoramic photography has not evolved into this direction. It usually deals with a spherical space surrounding the observer and is thus not suited to representing a space along a long line with a moving point of observation. (However, recent development has brought a new variety of tools for visual representation that remind this approach, such as the wall mode in Microsoft’s Photosynth, and more distantly the Google Street View.)
The challenge and reason why usual panorama stitching doesn’t work for this is the displacement of the camera, or parallax between two consecutive frames. A high frame rate (at least 60 fps, preferably 240 fps) helps to avoid image artefacts resulted by parallax, and a high shutter speed is needed to freeze the motion of the scenery passing by.
To achieve results that are photorealistic and not exclusively some kind of slit-scan art, an algorithm is needed that detects the variations in camera movement (eg. the varying speed of the car in the street), to add new image slices to the panorama as they best fit.
A project that resembles my current experimentations is the Danube Panorama project in which river panoramas of hundreds of kilometres have been made from river boats.
More images on my Travel Panoramas page.