The Evolution Of UAV Aerial Photography And Mapping
The history of aerial photography is historic and evolving. It started back in the 1860s from an individual hanging over the
basket of a tethered hot air balloon with a camera. Before the century was over aerial photography had evolved into kites.
And at the turn of the century pigeons actually carrying cameras. Then the First World War brought in the aircraft with an
individual hanging over the side with a camera. Aerial photography was a proven resource here to stay. Which would evolve
to high def cameras from all manner of aircraft to orbiting satellites.
Then dawned the Unmanned Aerial Vehicle: UAV - The Drone. Aerial photography morphed into a whole new industry of
high tech fixed and rotor wing aircraft. The technology evolution is hard to comprehend. These machines are high tech
computer marvels capable of taking standard photography all the way to survey mapping producing accurate Digital Elevation
Models denoting distances, elevations and volume. Also UAVs carrying special cameras which assess crop conditions and
thermal cameras denoting temp variations where required.
There are several manufacturers of UAVs. From basic camera drones all the way to the complex drones that have onboard
complex computing to solve complex problems and tasks. There is no main manufacturer of the simple camera drone. But
the main maker of the complex drone is DJI. No one competes with it’s stable of work horse drones and the tasks they provide.
The basic function of UAV aerial photography is simple photography used for all types of presentations. Such as scenic areas
and events. In commerce it translates to real estate with photos of a house, building, land and advertisement. In construction
it’s basic use is for progression monitoring of sites, structures, highways, power line condition, etc.
When delved into Digital Elevation Modules you are entering the realm of Photogrammetry and Lidar. These are specialized
UAVs that can be programmed to fly a specific flight path. They will carry cameras that will stitch together hundreds to thousands
of jpeg photos and/or a laser firing thousands of laser shots per second. Both used to replicate the ground surface.
Photogrammetry: The process of obtaining hundreds to thousands of photos obtained while flying a created grid path. The
photo are taken by a special camera on a GPS located UAV which are directed perpendicular to the ground. A camera position
know as Nadir. The UAV imprints XY and Z GPS info on every photo. The photos are then processed thru proprietary software
programs that stitch all the photos together into an image known as an Orthomoasic photo. The Ortho is made up of countless
photos that are stitched together in a pixelated image. Together with other files will show distance, elevation an volume. To give
accuracy, the data has to be collocated with known grown control points and the correct coordinate system for the area in
question. Which can be less than 2 tenths. Far less than 2 tenths. With 2 Tenths being the goal.
Lidar: This process of obtaining relative data has nothing to do with photography. It is done with an appropriate UAV carrying
a laser system known as LIDAR. The UAV flys a grid system as well. The laser fires thousands of times per second aimed directly
down at the ground. Nadir as well. It will obtain a Digital Surface Model the will show the ground elevations thru trees and
vegetation. The laser doesn't see thru vegetation and trees. The laser infiltrates. The thousands of laser pulses passes thru the
spaces of the vegetation. It is also run thru a special software program that processes all the laser pulses into a point cloud
image. Which looks very different then any photo or Orthomoasic image. But you have surface data. The Lidar image also has
to be collocated by GPS and the proper coordinate system. This system is very is hyper expensive due to the miniaturizing of
the equipment to attach to a UAV.
Both Photogrammetry and Lidar have their uses and pluses when used in the correct manner and setting as they are
completely different processes.
The evolution of aerial photography, inspection and mapping has been amazing over the last 5 years. It is sure to be just as
spectacular over the next 5 years.
Aerial UAV Photogrammetry
Aerial UAV LIDAR