Terrain correction is one of the gravimetric reductions applied to the value of the acceleration due to gravity. This work presents a comparison of the performance of the TC2DFTPL and TCFOUR programmes to see if there are significant differences between them when calculating the terrain correction for the state of Rio Grande do Sul. The results obtained for the programmes were similar. However, the TCFOUR programme showed an edge effect, unlike the TC2DFTPL programme. There was a difference between the statistical results for the maximum and minimum values obtained for the terrain correction calculated by both programmes using the SRTM and ASTER MDTs at 5 km, 2 km and 1 km resolutions. It was concluded that this difference is due to the need to divide the study area for the higher resolutions and also to the altimetric differences between the MDTs, which are more evident in the higher altitude region, such as the Serra Geral in the state of Rio Grande do Sul. This book is aimed at those interested and professionals in the field of Physical Geodesy. Happy reading.