Could Georeferencing Solve This Mystery?
It’s no secret the geospatial profession is making leaps and bounds both commercially and philanthropically.
From the use of GPS to operate cars without a driver, to the use of drones to assess forest fires, to the use of Geographic Information Systems (GIS) to map what help is needed where in the aftermath of earthquakes, professionals in the field are constantly developing extremely useful new applications for existing technology.
For Anthony Calamito, solutions architect at Boundless, tinkering with geospatial tools and exploring new ways they can be used to help solve real-world problems is a lifestyle. He’s full of creative juices, and goes to work every day with a mission to find and share the “art of the possible” with regard to the technology Boundless has on hand.
In a recent blog post at boundlessgeo.com, he conveyed how georeferencing could play a role in solving the mystery of the disappearance of Malaysia Airlines Flight 370. The Boeing 777 went off the radar March 8, 2014, making international news and exposing the world to the limitations of aircraft tracking. Now, more than a year later, no real answers have surfaced. However, plane debris was recently discovered off the coast of Reunion Island in the west Indian Ocean and has sparked new hope in the hearts of followers.
To assess the plausibility of the debris traveling to that location, Calamito has thoughtfully assembled a visual model that he hopes the expert investigators will find helpful. His trail of thought takes five separate and complex maps — the location of plane debris, ocean current, prevailing winds, vector data of search areas and the potential flight path — and overlays them so as to analyze how together they could interact and influence the direction of the debris.
What is Georeferencing?
“Essentially georeferencing means associating a geographic reference, hence the name, to content that doesn’t have one,” Calamito says. “In the example I used in the blog, we assigned coordinates so that that simple image that doesn’t necessarily have georeferencing behind it would align correctly with the other data I had inside of my GIS.”
Georeferencing, he says, is typically completed using software. In his case, Boundless’ OpenGeo Suite QGIS plugin was used. Software is necessary because a behind-the-scenes algorithm exists to help warp individual pixels of a particular image to align correctly over the earth’s surface. The most common ways the process is completed include GIS software or image-processing software, he says. “It’s a way we can essentially capture or illustrate change over time by looking at two [or more] different pieces of data and helping align them, so they arrive in the same geographic space.”
How can it be Applied?
Georeferencing can be used for many things, according to Calamito, who says you can adjust one vector data set to overlap another data set aligning, for example, a less accurate road data set from the 1980s with a more accurate one collected in 2010. You could also use it to take imagery that’s been collected from satellites and planes, and get it to warp correctly over the earth’s rough surface, correcting for the peaks, valleys and other complex terrain in the image. Quite often, he says, the practice is used to align historical paper maps that have been scanned into digital form on top of modern GPS-collected vector data.
What’s the Value of Georeferencing?
The real genius of georeferencing, according to Calamito, is the opportunity it offers to bring new data into a problem set. Whether that involves bringing in historical data in the form of old maps or imagery of different factors that coexist in the same space, it leads to gaining a better understanding of the problem set. “I think that’s the real power behind georeferencing — the ability to bring in multiple data sets that complement a particular problem that you’re studying.”
What’s the Catch?
Georeferencing’s actually been around for quite a while, Calamito says. “The earliest examples are probably image registration, which is something that’s been done in both the military and medical imaging fields for quite some time. They’re used to align two images of the same area for comparison.” In the military, georeferencing was used to help track things like troop and enemy movements over time. In the medical field, it was used in less of a geospatial sense, specifically to align two MRIs and track for things like change in brain tissue. But although georeferencing dates back to at least the 1950s, Calamito says there’s still a lot of room for error.
When it comes to the reliability of georeferencing results, value is highly dependent upon the professional choosing an adequate number of accurate control points. Control points, as explained in his blog, are real-world locations that are selected as reference points to warp an image to match the real world.
“I like to tell people that you can think of GIS like a toolbox,” Calamito says. “But rather than having hammers and screwdrivers, the GIS is full of analytical tools. So, subsequently, the analysis you perform is only as good as your ability to use that tool.”
Calamito’s georeferencing exercise exploring the debris path of Flight 370 should not be interpreted as anything more than an effort to examine how QGIS could be used to overlay data in the context of a real-world scenario, he says. “We don’t wish to make claims about where the debris traveled. We’re going to leave that to the experts.”
That said, Calamito does look forward to seeing what the experts come up with as far as determining the plausibility of the debris following the ocean current and wind patterns he overlaid. He is curious to see whether or not the mechanisms are found to be credible. “We’re still kind of waiting for the experts to give us their opinion,” he says, “so it’ll be nice to be vindicated, if you will, to show that we’re not just blowing smoke, but that this stuff actually does methodically and scientifically help understand where things could move to.”
As for the georeferencing process in general, Calamito says one of the holy grails of GIS and remote sensing has always been the idea of automatic image registration, and he’d like to see it happen. By automatic image registration, he means the ability for software to automatically generate control points and apply the georeferencing without manual assistance. Although many have tried to do it, it remains “that unicorn off in the distance,” he says. “It would certainly save time and certainly save money if we could find a way to automatically register imagery as it’s collected, but we’ll see.”
In the meantime, Calamito says the georeferencers of the world should remember that the key to success remains choosing the right control points manually, however time-consuming it may be.
“The best advice I can give,” he says, “is have patience and, as always, practice makes perfect, so don’t be afraid to do it two or three times until you get the most accurate solution you can possibly have.