Abstract
The collection of high-resolution data is helping researchers better
understand form, process, and change in river systems and, especially,
stream restoration projects. In the last 10 years it has become apparent
that there is no “one-size-fits-all” approach to collecting
high-resolution data for fluvial studies. The approach we demonstrate
here is a self-contained pole aerial photography (PAP) system capable of
collecting data for directly georeferenced structure from motion
photogrammetry. PAP can produce higher-spatial resolution data than
remotely piloted aerial system collected data and is one option where
RPAS are restricted, like in parks and protected places. Another
advantage of PAP is that it makes 3D data collection possible in parts
of rivers, like under riparian canopies, that can elude capture with
RPAS methods. Direct georeferencing removes the necessity for ground
control points, which can greatly decrease the amount of time needed for
a survey. The system that we developed combines a low-cost,
dual-frequency GPS receiver capable of Real-time and Post-Processed
Kinematic surveying with an off-the-shelf digital SLR camera, an
inertial measurement unit, and 3D printed mounts and housings. The
open-source control/survey software runs on an inexpensive Raspberry Pi
computer with a 7-inch (18 cm) touch screen display. We highlight the
accuracy of the system along with the high spatial resolution 3D data,
ortho imagery, as well as other data that can be derived from these
datasets such as sediment size measurements.