Photogrammetric Digitizing System

摘要

The acquisition of terrain data from aerial photography using digital photogrammetric methods gives the engineer and planner an economical alternative to conventional ground surveys. This paper describes a complete photogrammetric digitizing system developed for the Portland District Army Corps of Engineers. The hardware of the system consists of aWild AlO first order stereoplotter interfaced to an Altec AC-74 coordinate digitizer which is interfaced to both a Hewlett Packard 9810A programmable calculator and a Digi-Data nine-track magnetic tape recorder. The software of the system consists of photogrammetric routines developed for online computation by the programmable calculator and a sophisticated FORTRAN IV program called PHOTDIG which processes the digitized photogrammetric data from the nine-track magnetic tape at the Corps of Engineers data processing facility which contains an IBM 370 computer and a Calcomp 748 precision flatbed plotter. The processing of the digitized data by PHOTDIG produces terrain information required by engineers and planners such as state plane coordinates, elevations, cross-sections, profiles, etc. in both digital and graphical formats. The system has been in production use for over two years in the Portland District Photogrammetry Section and has significantly increased the efficiency and economy of photogrammetric data acquisition.