STATE-OF-THE-ART OF DIGITAL PHOTOGRAMMETRIC WORKSTATIONS FOR TOPOGRAPHIC APPLICATIONS

Digital Photogrammetric Workstations (DPWS) have become a major focus of research within the photogrammetric community in the last few years due to an increasing availability of digital imagery and a revolutionary hardware progress in computer science. Today more than a dozen DPWS are offered on the market and they are on the verge of replacing the analytical plotter as the main photogrammetric instrument for evaluating imagery. This paper presents the state-of-the-art of DPWS. A DPWS is the main component of a Digital Photogrammetric System (DPS), A DPS is defined as hardware and software for deriving input data for Geographic Information Systems (GIS) as well as for Computer Aided Design (GAD) systems and other photogrammetric products from digital imagery using manual and automatic techniques. Besides the DPWS itself, a DPS also includes A/D and D/A converters for the imagery (digital cameras, film scanners, and output devices for producing film and paper hardcopies). First, design issues of a DPWS are addressed. Then, the question of automation versus interaction is discussed, and it is pointed out where automation is possible in the chain of processing digital imagery. Subsequently, a classification of the different kinds of DPWS according to the products which can be derived is given. Then first experiences and results obtained by civil mapping organizations involved in digital photogrammetry and using DPWS are described. Finally, requirements for a broader use in practice and trends for further development in digital photogrammetry and in DPS are pointed out.