Evaluation of Heights Interpolation Methods Using Geographical Information Systems

Abstract

The geoid is an equipotential surface which coincides on the average with the mean sea level has significant relevance in geodesy, surveying and other earth related disciplines.This thesis focuses on the digital terrain modeling (DTM) technique based on geometrical interpolation approach by fitting a surface that depends on the reference points that are chosen in the critical and characteristic locations of the field to represent the trend of the surface. Using the orthometric heights for all the points were computed.A multiple regression model was formulated as the required geometrical model to further adjust the derived (DTMS) from observation. The main objective is to evaluate heights interpolation methods, and create a digital terrain models (DTMs) of base types of relief in two study areas (flatlands, hilly areas). This research focuses on the application of three interpolation methods (Kriging, Natural Neighborand Inverse distance weights) in geographical information system (GIS) to estimate the unknown value from the digital terrain models. Results from this study show the interpolation using GIS techniques is effective and has a higher level of accuracy compared to conventional methods, especially in the areas with similar terrain, based on statistic methods (standard deviation and Root Mean Square Error). Kriging method enable to determine an appropriate estimated elevation in unknown altitude regions, in the study area (A) where variations in the terrain are noticeable the accuracy is low, in the study area (B) where the topography is similar the accuracy is high.