VALIDATING UNMANNED AERIAL VEHICLE PHOTOGRAMMETRY HEIGHTS, FOR HIGHWAY TOPOGRAPHIC SURVEYING IN TANZANIA.

Abstract

Abstract

Demand for accurate topographic surveying data is huge to support ever-growing infrastructure development such as highway construction. Topographic surveying defines a point with X, Y, and Z relative values to create a 3D earth surface model. The Z values represent the vertical height of a point from the benchmark. Vertical heights can be obtained from conventional levelling, Digital Elevations Model (DEM) like heights from Unmanned Aerial Vehicle Photogrammetry (UAVP) and Global Navigation Satellite System (GNSS).

GNSS-Real Time Kinematic (RTK) is the most method but sometimes becomes obsolete, because of limitations in time consumption and physically inaccessible surfaces. Recently, UAVP Survey seems to be quick and access areas that could not be possible with GNSS RTK methods. UAVP has recently been reorganized through cheap, fast and simple methods but few researches have been documented. Therefore, the study for validating UAVP Surveying for highway topographic surveying in Tanzania is very timely.

In this study, the evaluation was performed by comparing UAVP Survey to GNSS RTK Method heights for 3km wide and 19 km corridor. 39 ground control points were used. The standard deviation between UAVP Survey and GNSS RTK method heights was ±1.4 cm. 80% were considerably accurate for highway preliminary surveying. 40% of the heights showed good accuracy satisfactory for detailed topographic surveying ±2 cm. This study confirms that UAVP Survey can be very helpful for highway preliminary surveying in Tanzania to the areas with less vegetation like Dodoma but cannot guarantee good performance for detailed topographic heights requirements in Tanzania.

Keywords: UAV, GNSS RTK, Heights, Topographic Surveying