ABSTRACT: Digital Stereo Display and Measurement

T. H. L. Williams, Zeev Berger

The French SPOT satellite provides both multispectral and panchromatic stereo with a respectable base-height (b/h) ratio. However, much of the stereo interpretation of this data has been based on conventional analysis of photographic hard copies of the imagery, losing much of the inherent value of the digital format. Various approaches to displaying stereo imagery on a CRT monitor have been developed. Each approach offers particular advantages and disadvantages in display size, color capability, visual quality, ability to zoom and roam the stereo image, mensuration, and compatibility with existing image-processing systems.

We display stereo data with a system that alternates the left and right images on the screen at 120 Hz to give 60 stereo views per second with no visible flicker. A combination of electronically switched LCD screen and passive polarized viewing glasses presents the left and right images to the viewer's left and right eye, respectively. With the on-screen stereo, we are able to radiometrically and geometrically match the left and right images and apply tonal and spatial enhancements interactively to the stereo image.

In addition, we have developed a digital parallax bar to measure point elevations and dip and strike. Point elevation accuracies of 14 m were achieved on images with a 0.7 b/H ratio. The accuracy of slope measurement is a function of point elevation precision, slope angle, and slope length. Preliminary results indicate that dip measurements acceptable for photogeomorphic interpretation can be made in both low-relief and high-relief terrains using this technique.

The system is compatible with image-processing systems operating on microcomputers, minicomputers, and workstations and is a useful and effective addition to existing image-processing capabilities.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990