In hard-to-reach places, where the use of standard reflectors is not possible, points are often signalized by retro reflective targets. To determine the movements of such objects, high precision is required, which is achieved by using the appropriate geodetic equipment, appropriate selection of the measuring method, and appropriate signalling of points.
Due to the frequent use of retro reflective targets, we wanted to test the automatic target recognition system on retro reflective targets. We have compared measurements, obtained by automatic target recognition system with manual measurements.
In order to carry out the measurements, we established a test field. Measurements were obtained by two modern electronic instruments manufactured by Leica Geosystems. Retro reflective targets, used as a signal, were different sizes, with a different rotation and at different distances. We measured horizontal directions, zenith distances and slope distance in multiple repetitions on several retro reflective targets.
By using statistical methods, we wanted to determine whether it is sensible to use the automatic target recognition system when measuring on retro reflective targets. Based on analysis result we concluded, that automatic measurements are less accurate than manual. Manual and automatic measurements are in most cases statistically different, which can be summarized: automatic measurements on retro reflective targets are not reliable.