Comparison of UAV photogrammetry and conventional GNSS in the estimation of road construction earthworks.
Abstract
The efficiency of volumes determined in various fields of survey; mining, quarry, hydrographic and
engineering fields can’t be overemphasized. Conventional surveying method using GNSS has been
the most used for volume determination in surveying over the years, despite its long, risky and
laborious data collection in sites. Even though, the Unmanned Aerial Vehicle as a platform has
been an alternative in surveying, there have been doubts about its efficiency and accuracy. This
project compared the applications of two novel surveying technologies of UAV and GNSS data
collection platforms for earthwork volume estimation and also compared time spent employing the
methods for data collection. For this purpose, an appropriate area (specified chainages) along
Busega-Mpigi express way was chosen, two sets of observations were taken. First, the area was
mapped by a UAV flight, and secondly measured using a GNSS. Pix 4D Mapper image processing
software was used. The results have been analyzed with respect to differences in volumes and
project time between the methods for data collection. After detailed analysis and comparison, it was
found that both methods yield better and accurate results making both methods comparative for
earthwork volume measurement. It was also realized that for this project, GNSS volume differs
with that of the actual volume with 2.93% compared to UAV that showed a -0.54%. Consequently,
it was also observed that using conventional surveying methods such as GNSS surveying volume
estimation is more time consuming and the results are more generalized than using UAV
technology where capturing thousands of surface points (i.e., point cloud) takes just seconds. In
conclusion, the results show a promising future for UAV in volume estimation and surveying