HORIZONTAL POSITIONING OF TRANSPORTABLE DIGITAL ZENITH CAMERA
The laboratory for Geodesy and Geodynamics at the Federal Institute of Technology (ETH) in Zurich developed a portable digital Zenith-Camera to take pictures of the stars in the zenith. Using astrometric methods, it is possible to determine the local plumb deviation from these digital star pictures.
With the help of this information it is possible to define the so called „Geoid“ which is the reference plane at sea level, which then allows to link GPS information with topographical information.
In order to define a high precisely local plumb direction as well as plumb deviation, the Zenith-Camera must be levelled very precisely, when taking a picture of the stars. Because of outdoor application, a temperature range of –20 up to +40 °C must be covered.