  Accurate measurement of blast-induced rock fragmentation is of great
importance for many mining operations. The post-blast rock size distribution
can significantly influence the efficiency of all the downstream mining and
comminution processes. Image analysis methods are one of the most common
methods used to measure rock fragment size distribution in mines regardless of
criticism for lack of accuracy to measure fine particles and other perceived
deficiencies. The current practice of collecting rock fragmentation data for
image analysis is highly manual and provides data with low temporal and spatial
resolution. Using UAVs for collecting images of rock fragments can not only
improve the quality of the image data but also automate the data collection
process. Ultimately, real-time acquisition of high temporal- and
spatial-resolution data based on UAV technology will provide a broad range of
opportunities for both improving blast design without interrupting the
production process and reducing the cost of the human operator. This paper
presents the results of a series of laboratory-scale rock fragment measurements
using a quadrotor UAV equipped with a camera. The goal of this work is to
highlight the benefits of aerial fragmentation analysis in terms of both
prediction accuracy and time effort. A pile of rock fragments with different
fragment sizes was placed in a lab that is equipped with a motion capture
camera system for precise UAV localization and control. Such an environment
presents optimal conditions for UAV flight and thus, is well-suited for
conducting proof-of-concept experiments before testing them in large-scale
field experiments. The pile was photographed by a camera attached to the UAV,
and the particle size distribution curves were generated in almost real-time.
The pile was also manually photographed and the results of the manual method
were compared to the UAV method.
