Yadvendra Singh Rawat*, Onkar Dikshit, B Nagarajan
The Geoid surface is an equipotential surface that approximately coincides with the mean sea level. Therefore, modelling of such surface will speed up and assist the rising necessities in modern surveying and mapping practices which will further help in planning and management. This research work is based on the development of a regional Geoid undulation model using Global Navigation Satellite System (GNSS) and levelling observations. The study area is taken as the Kanpur Nagar district and parts of Unnao district and Kanpur Dehat district, which covers up an area of around 25 km (East-West) × 28 km (north-south), i.e. approximately 700 km2. A network of 40 Ground Control Points (GCPs) is established in the region on which Geoid undulation is computed. A 5-fold cross-validation test is performed for selecting the best-suited interpolation method in the region. Thus, Geoid model is developed by interpolating the Geoid undulation values at 35 GCPs over the entire considered area. An accuracy of 4.4 cm was achieved after interpolation. A Geoid undulation model of 5 cm contour interval drawn shows the Geoid undulation in the region. A comparison of Geoid undulation values computed on earth gravity model 2008 with the regional Geoid undulation values by GNSS/Levelling method is also made to check the difference between the two.