Astrogeodetic Geoid for Austria using Least-Squares Prediction Technique for Densifying the Deflections

The paper presents a technique for densification of the deflection data using least-squares remove-predict-restore technique. The available deflections of the vertical have been topographically-isostatically reduced using the Airy isostatic hypothesis. The reduced deflections have been used to interpolate deflections on a dense grid covering the data window using the least-squares remove-predict-restore technique. These gridded reduced deflections have been used to compute astrogeodetic geoids for Austria using astrogeodetic geoid determination technique introduced by Helmert with different remove-restore schemes. For the sake of comparison, an astrogeodetic geoid for Austria has been computed using the topographically-isostatically reduced deflections at the data points without densification. Computed geoids have been fitted to the GPS/levelling derived geoid. The results proved that using the least-squares remove-predict-restore technique gives densified deflections with good precision. The results also showed that densifying the deflections using the least-squares remove-predict-restore technique in the framework of the Helmert astrogeodetic profile transformation gives better geoid accuracy.