DEVELOPMENT OF AN INEXPENSIVE IMAGE SPACE PLOTTER

This paper discusses an inexpensive, analytical system designed for a forestry application of photogrammetry. It is presented in two parts. Part I describes an image space plotter that was built in New Zealand and is operating there. The system uses a digitising table to collect left-hand photograph co-ordinates. an encoded micrometer bar to measure × parallax and a mirror stereoscope for viewing photographs. The mathematical, formulation is based on simplifications first suggested by E. H. Thompson. Good accuracy in ground heights can be achieved by the system, but only poor accuracy in planimetric co-ordinates. The cause of poor planimetric accuracy is investigated in Part II. Two error sources are apparent: the simplified analytical theory and systematic errors from the digitising table. Part II also investigates the relationship between random errors in image co-ordinate measurements and system accuracy.