Close Range Photogrammetry for High-Precision Reference Point Determination

Abstract

AbstractLocal tie vectors are a crucial component within the combination of several space geodetic techniques. The vectors define the geometric relations between the space geodetic techniques, referring to the invariant reference points of such techniques. The Global Geodetic Observing System aims for an accuracy of 1 mm in the position on a global scale. In ITRF2014, about 50 % of the used local ties show discrepancies of more than 5 mm w.r.t. the global solution. In the framework of the IAG/IERS Working Group on Site Survey and Co-location or joint research projects like the international GeoMetre project strategies to improve the reference point determination and the local ties are developed. Strategies mainly comprise the development or the recommendation for surveying instruments, developing approaches for transforming local measurements to the global frame, and deriving innovative analysis procedures to derive the reference point of space geodetic techniques.In this contribution, we focus on the reference point determination. At the Geodetic Observatory Wettzell, a measurement campaign was carried out in September 2020 to evaluate the benefit of close range photogrammetry in the framework of reference point determination. For this purpose, the invariant reference point of a Satellite Laser Ranging telescope was derived several times using various configurations. The estimated reference point and the axis offset vary in a range of ±0.1 mm and ±0.02 mm, respectively. The resulting standard deviations of the coordinate components of the combined solution are less than 0.1 mm and impressively demonstrate the potential of the presented method.