Stereo Image Digitizer For An Automatic Feature Extraction System

Abstract

A flexible image digitizing system is under development to provide for digitization of stereo photographs and graphic materials in an automatic feature extraction system. The digitizing system employs two servo-controlled photograph stages and linear CCD array cameras to scan stereo photographs for image digitization. Raster scanning is accomplished by moving the photograph in a direction approximately normal to the array while reading out successive lines of video from the array. The photograph scanner optics contain zoom magnification and rotation capabilities, providing variable resolution and an ability to correct first order geometric image distortions. Graphic input materials are scanned by a separate line array camera mounted on the plotting head of an XY plotter. The digitizer system employs a hardware digital video processing unit to correct for dark signal and gain variations of the linear arrays. This processor also corrects for geometric distortions of the lens systems and arrays. Control of the overall system is implemented with a minicomputer, which provides scanning, data transfer, calibration, and setup functions of the system. Peripherals of the minicomputer include a large dual access disk storage unit for image data storage and transfer to the main computer of the automatic feature extraction system.