Electronic theodolite intersection systems
The development of electronic surveying instruments, such as electronic theodolites, and concurrent advances in computer technology, has revolutionised engineering surveying; one of the more recent examples being the introduction of Electronic Theodolite Intersection Systems (ETISs). An ETIS consists of two or more electronic theodolites and a computer, with peripheral hardware and suitable software. The theoretical principles on which they are based have been known for a long time, but intersection has seldom been used as a method of measurement. The main reasons for its re-evaluation were the introduction of one-second electronic theodolites and the ability to interface these on-line to a computer. The last decade has seen the development of several commercially available systems and probably even more in-house developed systems. Such systems are capable of performing real-time, non-contact, three-dimensional coordinate determination to a high accuracy, enabling their use in a wide variety of applications. This thesis details all aspects of ETISs. Initially, the theoretical principles on which the systems are based are developed. The components of a system are then detailed and a review of current commercially available systems and their applications is given. The thesis then concentrates on the development of an ETIS by the author and details its' application in both industrial measurement and deformation monitoring. Finally, the thesis concludes with a discussion on the factors affecting the accuracies attainable with ETISs.