Table 4 displays more results as they relate to the RTS and UAV comparison.
It includes a comparison of how long each survey technique
took. Since measurements using RTS and UAV were taken from 142 accessible
locations on the project, the circles in Fig. 8 display at what locations
(center of yellow circles) the error of the UAV system was high
and small (large and small circles, respectively). The numbers in
Fig. 8 indicate the differences in the elevation measurement. Negative
and positive values indicate the UAV measured the point too
low or too high, respectively. The average height error between the
RTS and UAV measurements was 4.2 cm with a standard deviation
of σ = 5.9 cm.