Unmanned aerial systems (UAS, formerly called unmanned aerial vehicles), which the U.S. military has routinely used abroad for more than a decade, will soon be a standard tool for many civilian applications — including police surveillance, fire mapping, border security, real estate photography, and surveying structures after natural disasters.
"There is really a shift happening in the market, from the military side to the civil side, with future growth on the commercial side of the industry," says Gretchen West, Executive Vice President of the Association for Unmanned Vehicle Systems International (AUVSI). The association has about 7,000 individual members and about 600 corporate members, most of whom are involved in the unmanned aircraft industry.
In the near future, changes in the regulatory environment will influence this market as much as technological developments. In the United States, the Federal Aviation Administration (FAA) is creating guidelines and standards for the use of UAS, projecting that 30,000 will be flying above the country by 2020. The agency is required by law to publish a final rule on the integration of small UAS into the national airspace by August 2014 and to complete their safe integration by September 2015.
"Once the FAA streamlines the processes, allowing for integration of UAS into the national airspace, we believe that we will see a much broader use of them for civilian purposes," says West. In particular, she sees a huge demand for surveying. UAVs, which are cheaper and easier to operate than piloted aircraft, will soon be the remote sensing platform of choice for photogrammetrists, surveyors, and other geospatial professionals, and many new applications will emerge to take advantage of this new capability.
"When Trimble bought Gatewing, they put that product under their survey group, rather than their airborne group, which is really a telltale sign of what their market research says," points out Matt Bethel, Director of Technology at Merrick & Company. "Our main competitors are probably ground-based laser scanners rather than aerial mapping companies," says Rowland Harrison, International Sales Director at Hawkeye UAV Ltd. "It seems that the main adopters of our technology now are surveying companies."
UAS can accomplish safely and efficiently a variety of remote sensing tasks that would be too dangerous, difficult, or expensive to perform with piloted aircraft. In April 2011, when the Red River flooded in the Midwest, UAS were used to survey the damage and provide critical information on a real-time basis. In Japan, after the March 2011 tsunami, they were used to approach the damaged Fukushima nuclear power plant.
They can be flown through volcano plumes or hurricanes to collect data about them, or used for event or port security. The Arlington, Texas, Police Department has been using a small Leptron helicopter UAS — which weighs less than 25 pounds — to survey multi-car crashes on interstate highways. "That puts troopers out of harm’s way, because they don’t have to be on the highway and it is a faster way to survey the damage and clear congestion," West points out.
Ben Miller, with the Mesa County, Colorado, Sheriff’s Office, uses UAS for search and rescue missions and to take aerial photography of crime scenes. He estimates that it costs his agency $25-75 per hour to fly its UAS, compared to about $250-650 per hour to operate its manned helicopter. See Figures 1-3.
The key improvements in UAS over the past few years have been miniaturization, automation, and integration with image processing software.
Miniaturization has enabled the production of UAS that weigh just half a kilogram to three kilograms. This was essential to address the high safety concerns in the civilian market, says Andrea Hildebrand, Director of Sales and Marketing at senseFly and the company’s founder.
Automation has made UAS much easier to operate for the typical user — such as a surveying company. For example, Hildebrand says, senseFly’s Swinglet CAM is very easy to operate right out of the box. "Flight planning is quick, the launch is very easy, and it is all autonomous." See Figures 4-5.
Likewise, Gatewing’s X100 enables a user to map an area by selecting the area he wants to fly, performing a few checks, and then putting the vehicle on the launcher, says Peter Cosyn, the company’s Director of Research & Development. "It will fly truly automatically. The user no longer needs to give any remote control inputs."
Gatewing, senseFly, Hawkeye, and other manufacturers of micro-UAS have also fully integrated their hardware with image processing software. They either provide it to their clients directly or refer them to trusted providers. "In the past few years," says Bethel, "rigorous software has been emerging that produces accurate products in a black box form, such that someone who is not a photogrammetrist or a remote sensing scientist can process pretty accurate data."
There has also been a big effort to make the systems comply more with future regulations by adding all kinds of automatic safety procedures, such as routines to handle GPS errors, Cosyn points out. "Many of these things already existed, but typically not on board these small UAS."
Together, these developments have enabled low-altitude photogrammetry. "Aerial mapping companies typically capture 50, 100, or 200 large-format images per flight," says Harrison. "A UAS at low altitude captures about 1,200 images per flight."
In the next two or three years, UAS will become even more user-friendly, argues Cosyn. "Routines might be introduced to meet particular regulations. The sensors are becoming larger, but they are very compact, so that they fit in a very small aircraft. This is improving the quality of acquisition, which means that the quality of the data is improving. Soon, you will have photogrammatic systems that will compete with LiDAR quality."
"A big improvement," says Harrison, "would be sensors better optimized for the different types of markets — near-infrared, multispectral, and hyperspectral. All of those sensors are becoming more miniaturized. There hasn’t been a demand for miniaturization, but now there will be." According to Hildebrand, one of the next big developments will be obstacle avoidance and mid-air collision avoidance. "This will make UAS operations even safer and more integrated into the air space."
According to Bethel, the market will converge on medium-size UAS, such as the Buckeye, which are able to carry a few hundred pounds. "That’s plenty good for most remote sensing capabilities," he points out. He expects "the next big leap" to be a move toward medium-format cameras. "Right now, one of the biggest complaints about UAS-based image collection is that there are so many images to deal with. You collect one square mile area and it might take 50 or 100 images to cover. Many vendors are moving in the direction of combining multiple medium-format cameras to cover larger areas in a single flight swath."
How do the capabilities and operating costs of UAS compare with those of piloted aircraft? The capabilities of some of the bigger UAS are closer to those of piloted aircraft, while micro- UAS are very complementary to them. Piloted aircraft are more efficient for covering large areas. However, a UAS enables a user to cover an area frequently — say, cover a mine twice a week — and perform change detection, which would be prohibitively expensive with a piloted aircraft. Additionally, Hildebrant points out, micro-UAS are silent and do not pollute.
UAS are easier to deploy and fix, cheaper to operate, and more flexible than piloted aircraft. "You can typically bring with you extra UAS parts or even an extra UAS," says Bethel. Additionally, pilots, being human, can get sick, and miss important weather opportunities for flying, or get distracted, and miss flight lines. "A UAS is more predictable and more reliable." Currently, he acknowledges, there are trade-offs in square miles per day. "However, we all expect that over time, UAS are going to be able to go to higher altitudes, to cover larger areas; sensors are going to improve, and so on."
One reason UAS are much cheaper to operate than piloted aircraft is that the latter require both a pilot, who flies the aircraft, and an operator, who operates the sensors — while a UAS requires only one person. "So, labor fees for salary, hotels, and incidentals are cut in half," says Bethel. "You go from a minimum of two people to a minimum of one person."
Contrasts in System Stabilization
The smaller an aircraft is, the more it is subject to turbulence, which is especially present at low altitudes. There are a few main ways to deal with this: in flight, by making course corrections every few milliseconds, or post-flight, either by geo-referencing the imagery on the basis of data from an onboard GPS-IMU (inertial measurement unit) or by pixel matching. Typically, these methods are used in combination.
"We deal with turbulence by briefly switching the control from normal GPS navigation to a mode where we stabilize the UAS in a level position while it takes the photo," explains Hildebrand. "This ensures that the photo is not blurred and is properly oriented towards the ground. The residual orientation variations are estimated and compensated by the photogrammetric post-processing of the images."
"Turbulence is corrected in your photogrammetry technology, which has to handle off-nadir positions," says Harrison. "You cannot get into direct geo-referencing. You are not going to get the quality inertial measurement units into a UAS and, if you do, you end up with an ITAR-restricted product that you can sell to only a few count-ries," he argues, referring to export restrictions in the International Traffic in Arms Regulations.
"You can buy a remote sensing system for as little as 10,000 Euros," says Cosyn, "but then you are limited to flying in good weather conditions. You can buy a system for 50,000 Euros and be able to fly it in most weather conditions, so that the actual cost of your project is very low. If you use very small systems, weighing only a few hundred grams, then you depend on the weather. If you have a fast system that weighs about 2 kilograms, it can fly in practically any condition very close to the surface and still deliver a dataset of 2-3 centimeter ground sample resolution without any problems."
The accurate angle and position information, he explains, comes from the pixel matching. However, in order to have quality data, you need to be sure that you can have a consistent dataset, with consistent overlap. "This means that, although your aircraft can move a bit and it can take pictures at small roll or pitch angles of deviation from the vertical, it needs to do this within a certain limit. Having a few degrees of roll and pitch is no problem at all. The sensors on board the UAS are not accurate enough to register these small angles up to second level. The computation of the actual value of these angles is then done by the software, via pixel matching, which is very accurate."
For wide-area mapping, the LiDAR and the camera do not need to be rigorously stabilized, says Bethel. "We fly many sensors on board a helicopter that vibrates quite a bit and as long as the IMU can model that vibration it can put every point and every pixel right where it needs to be within our accuracy specification."
Meanwhile, a lot of R&D work is focused on developing extremely stabilized rotor-based UAVs, either in typical helicopter form or as multi-copters. "They are taking hundreds of measurements per second to counteract the potential vibration of the aircraft," says Bethel. "So, in the lower altitude, rotor-based UAV market, that stabilization is already at an excellent level for any type of collection and an IMU can account for any remaining vibration."
Differences Among the United States, Europe, Japan and Australia
Regulations on the use of UAS vary from country to country. "While Europe is aggressively working towards implementing standards for UAS use," says West, "Japan is already allowing UAS use commercially and Australia (which has a less congested airspace) is also aggressively pursuing UAS flight. Through the International Civil Aviation Authority, work is being done on a global basis to create global standards for UAS integration and the various countries are bringing their varying regulatory practices to the table for discussion and thought.
"We see the regulatory environment converging on both sides of the Atlantic," says Cosyn. "In the end, there will be little difference between the European Union and the United States."
"There will be a huge surge in adoption of UAS, for example by surveying companies, because the quality of these point clouds is really getting very good and the value that they add to projects is very high," says Cosyn. "While bigger companies will buy UAS, smaller ones might rent a system or do projects with larger companies that have one."