For international projects that use georeferenced data sets, such as the EXPLO project, it is important that all participants know the locally used coordinate systems. At the start of the project a common coordinate system must be defined so that all measurements can already be carried out in the correct coordinate system. This method prevents the mix-up of coordinate systems at the project’s end, which can leave the measurements useless. In the course of the bachelor thesis *‘Koordinatentransformationen und Messsysteme für Unterwasser-Archäologische Projekte in Südosteuropa’* (ETH Zurich, Institute of Geodesy and Photogrammetry) the coordinate systems used in Albania and North Macedonia were researched. The PROJ program was used for the transformation between coordinate system and examined for the accuracy of these transformations. PROJ can be used for the transformation without any problems.

Another part of the bachelor thesis targeted the development of a measurement concept for underwater measurements and the evaluation of an alternative concept for underwater measurements used in previous campaigns. The first uses a GNSS receiver with an IMU (**Fig. 1**) so that the measurements can be taken without the antenna standing vertically above the point. The other uses a total station and a 360° prism to measure the surface of a sphere (**Fig. 2**) and then calculate the center point and radius. With both methods, a diver holds the measuring stick on the marked point and a swimmer aligns it above water.

**Reference**

Fandré, Marie-Josianne. 2020. *Koordinatentransformationen und Messsysteme für Unterwasser-Archäologische Projekte in Südosteuropa.* Institut of Geodesy and Photogrammetry, ETH Zürich. Zürich : s.n., 2020. Bachelor thesis. Unpublished.

Fig. 1. Measurement concept with GNSS antenna, the swimmer aligns the antenna so that the measurements can be carried out (modified after Fandré, 2020).

Fig. 2. Measurement concept with a total station, the swimmer moves the prism so that the surface of a sphere is covered (modified after Fandré, 2020).

Marie-Josianne FANDRÉ, Zurich