Coordinatograph

Abstract: Publisher Summary This chapter discusses the various types of measuring instruments, accuracy, and reliability In extracting quantitative data, the primary requirement of instrumentation is to obtain coordinates with the supplementary requirement of a facility for continuous plotting The two principal approaches are analogical and analytical The former involves double-projection optical-mechanical analog systems in which replicas of objects are created for the acquisition of data In the latter, computer-interfaced comparators are used to derive the required data computationally Each approach has three basic components which include the viewing system, the measuring system, including the orientation mechanisms, and the readout and recording system An analytical plotter consists of a precision stereocomparator and coordinatograph interfaced with an electronic digital computer plus other auxiliary devices as may be necessary These plotters are capable of solving a wide variety of photogrammetric problems A digital terrain model is a numerical description of the surface of an object in terms of the X, Y, and Z coordinates of points on the surface This is usually done with an ordered array of numbers, which can be based on measured and derived coordinates of discrete points on the surface