YTU Davutpasa Congress Center 22 – 25 October 2013 Investigation on Accuracies of some of GNSS Methods for GIS Applications Huseyin Kemaldere 1 , Cetin Mekik 2 , Mehmet Alkan 3 1 Geomatics Engineering/Bulent Ecevit University/Turkey kemaldere@hotmail.com 2 Geomatics Engineering/Bulent Ecevit University/Turkey cmekik@hotmail.com 3 Geomatics Engineering/Yildiz Technical University/Turkey mehmetalkan44@yahoo.com ABSTRACT In this study, utilization some of GNSS methods to update Geographic Information Systems is investigated, compared with classical terrestrial surveying methods and these methods are examined in terms of accuracy, economy and time. First of all, six bench marks were observed by static GNSS method. Then, not only these six bench marks but also eight object points were observed by rapid static GNSS method. Thereafter, these fourteen points were observed by Classical RTK GNSS method and Network RTK GNSS method (FKP and VRS). Also, eight object points were observed by classical terrestrial surveying method. In the study, the results obtained from static GNSS method were accepted as accurate. Although the Network RTK GNSS method is more advantageous in term of economy and time, it is the worst method in terms of accuracy. When the accuracy is taken into consideration, rapid static GNSS method is the best method where the classical RTK GNSS method is better than classical terrestrial surveying method. KEYWORDS: RTK GNSS, Network RTK GNSS, Accuracy, Static GNSS, Data Acquisition, GIS. 1. Introduction Obvious to everyone in the GIS sector, data acquisition, which reportedly accounts for 60- 80% of the overall costs of a GIS project, plays an important role in GIS applications (Hunter, 1996). The fact that a cost-effective and reliable GIS requires speed and accuracy in obtaining