Total Station Technology
Total stations are precision instruments that combine an electronic theodolite (for angular measurement) with an electromagnetic distance measuring device (EDM). From the angles and distances measured to a prism held at selected positions we can calculate coordinates of the points.
Point coordinates can be stored on an external datalogger or, increasingly with modern instruments, directly into the memory of the instrument, and feature codes attached. When the data is downloaded software can be used to process these codes, applying lines and symbols to generate maps and plans.
Total station technology is still evolving. Many total stations now have the option to operate in reflectorless mode over shorter ranges; the distance is measured directly to the object itself, without the need for a prism.
Another important development is the robotic total station. This instrument is controlled by the operator remotely from the prism position, with motors driving the rotations of the instrument to track its position. This has the advantage that the operator can work without an assistant, increasing efficiency, and is at the object end of the surveying operation, where the important decisions have to be made.
Finally integrating other survey technologies (GPS, laser scanners) into the one instrument is also a feature of some new products.