What is Photogrammetry?
This is the story of how aerial photogrammetry has evolved from balloons and kites to drones
From the good folks at Merriam-Webster:
DEFINITION: the science of making reliable measurements by the use of photographs and especially aerial photographs (as in surveying) ORIGINS: International Scientific Vocabulary “photogram” photograph (from phot- + -gram) + -metry DATES BACK TO: 1875
There’s a lot more to the story…
Since the day Wilbur and Orville Wright turned a bicycle into a flying machine, photogrammetry and the airplane were destined for one another.
As it turns out, the world was never flat. However, an easy way to get up in the air to cover the earth with an accurate map was almost non-existent. Sure, there were hot air balloons and kites, but that was hardly a recipe for a controlled environment. Other mapping means were not functional as the second industrial revolution spurned skylines that made perspective mapping accuracy a near impossibility.
It only took five years after the Wright Brothers’ first flight for Italian Captain Cesare Tardivo to use the airplane to take the first aerial photos for mapping purposes. By 1914 the first mounted camera made its way onto an airplane. In short, it took less than fifteen years for an industry to get off the ground (literally). The technology went from earth to sky, but didn’t stop there…
From sky to space:
SATELLITE IMAGERY
October 4, 1957 (7:28 PM) is a day that stuck like glue for those who were old enough at the time to remember it. The world changed forever when the USSR launched Sputnik, the world’s first satellite, into orbit. It was just 2 years later in 1959 when Explorer VI, an American satellite, took the first picture of the earth. Like many advancements in technology from that era, the meteoric rise of satellite technology during the cold war was a by-product of the struggle for supremacy between the USSR and the USA. In fact, there are currently (2014) 2,271 satellites in orbit around the Earth.
In April of 2005 Google added satellite imagery to its broadening map viewing platform, signifying a shift in accessibility of satellite mapping. To date, over 1 billion people around the world have downloaded Google Earth. Commercially, stereo satellite imagery provides a great resource for orthoimagery creation on a global scale.
Massive Expansion in Image Acquisition:
UNMANNED AERIAL SYSTEMS(UAS)
UAS, or drones, as they are commonly known, are the latest advancement in the photogrammetric process. As alluded to above, balloons and kites were sometimes used for aerial imagery, but they had some obvious shortcomings. In 1937 the first competition was held in a new kind of hobby: remote control aircraft. These remote control aircraft were merely toys at their outset, but they’re actually the predecessor to today’s drones. Although the term “drone” attracts negative attention as a tool of espionage and war, they also broaden the possibilities of mapping firms around the world. Today drone capabilities are being integrated to increase the speed, efficiency and cost effectiveness of data collection and mapping.
For a deeper look at drones, and their integration into society, please check out our infographics across multiple social media platforms.
Project Example:
Highway F in Wisconsin
LOCATION:
Rock County, Wisconsin
OBJECTIVE:
Provide high accuracy mapping to support final design for road realignment and repaving
KEY POINTS:
- Cost Savings: Utilizing photogrammetry for some aspects of field survey saved the design engineer $8,000
- Integration: The DTM and contours integrated tightly to the supplemental field data collected by the survey crew
- Design Ready Deliverables: Deliverables were design ready and easily brought into CAD for the design engineers to utilize
- High Accuracy: Accuracy needs based CAD deliverables supported final design
As communities grow, roadway infrastructure often becomes unable to support the increase in traffic and speeds. What was initially country highway with 90 degree turns and limited shoulders must be redesigned to support a speed appropriate turn radius, vertical and horizontal road alignments, and an improvement in pavement quality.
For some time Rock County was discussing and evaluating the redesign of County Highway F running from Janesville to Edgerton in Rock County, WI. Supported by state funds from the Wisconsin Department of Transportation, the county embarked on a project to complete a redesign of that 8 mile stretch of road.
The county selected a design contractor but was unable to complete contract negotiations due, in part, to price. The design contractor engaged with Continental Mapping to supplement their field crew survey estimate with a photogrammetric mapping approach. Their surveyors still completed all photo control and topographic survey in obstructed areas but Continental Mapping saved the design engineers $8,000 by flying the roadway and completing planimetric mapping and a Digital Terrain Model (DTM).
Continental Mapping successfully delivered 1”=50’ planimetric mapping and 1-foot contours (0.3’ RMSE). All data was provided in MicroStation and Civil 3D formats.
NOTE: This is a brief overview, and a far cry from all that’s involved in the photogrammetric process. For more information please visit: www.continentalmapping.com
