Advancement through Consolidation

Abstract

The last half of the 20th century saw remarkable technical innovations in the field of surveying in general, and survey engineering in particular. These innovations, initially the tools of the geodesist, eventually became common among land surveyors, bringing geodetic quality measurements to surveys of ordinary extent. The first innovation was the electronic distance-measuring instrument EDMI . The first commercially available EDMI, the Geodimeter NASM-2, was introduced in 1950. The advent of the EDMI freed the surveyor from physically traversing the ground he measured. Twenty years later, in 1971, the combination of EDMI and theodolite, in the form of the Geodimeter 700 and the Zeiss Reg Elta, created the total station. The eventual coupling of the total station and field computer completed the modern data collection system almost universally employed by the modern surveyor. In 1990, Geodimeter introduced the first robotic total station, the System 4000. The final step in the evolution of the 20th century total station was the reflectorless EDMI. The first coaxially mounted reflectorless total station, the Leica TPS 300/ 1100 was introduced in 1998. More liberating to the surveyor was the introduction of the Global Positioning System GPS . Even before reaching full operational capacity in 1995, GPS removed the requirement for line of sight that remained with EDMI. With GPS, the only physical constraint for measuring is a view of the sky. GPS has redefined the way surveyors access the National Spatial Reference System NSRS . Following the original paradigm of physically monumented networks, more accurate networks were created using GPS observations. Known as High Accuracy Reference Networks HARN , these networks upgraded the accuracy of the North American Datum of 1983 NAD83 . GPS observations on the HARN began in 1986 and were originally completed in 1997. Even before the completion of the HARN, the first Continuously Operating Reference Station CORS was established in 1994. By the end of the 20th century, over 200 CORS were operating in 48 States. The CORS network has continued to expand and currently over 900 CORS sites operate in North and Central America and the Caribbean. Paralleling these innovations in measurement technology are equally rapid advances in communication. The Internet and email have forever changed how information is disseminated. Information is available over the internet on demand. Since the turn of the century, these tools have continued to mature; the range of reflectorless total stations has increased; and improved GPS receiver and antenna designs have decreased multipath and increased tracking ability. However, the innovative trend is toward a consolidation of existing technologies. Surveying technologies are merging in synergistic combinations that augment and enhance their efficacy. Surveyors have never been able to rely on any single technology alone; but new tools that combine several complementing technologies blur the difference