LOGAN (AP) — Soaring above the Quad on a recent afternoon, a white blimp controlled by Utah State University graduate students was almost hard to spot against the Cache Valley's overcast sky.
The only object that was clearly visible was a black digital camera, snapping one picture every five seconds, providing color geo-referenced aerial photography of the entire Quad in UTM (metric) coordinates.
The students were conducting a lab by running a blimp survey for Joseph M. Wheaton's geographic information systems class. The objective: To provide aerial imagery of the entire Quad. The 1,000-plus pictures the blimp provides them with will be used to make an image that can fit "on top of" the images on Google map, said Bryan Watt, a USU graduate student in the class.
"It will give you a much higher resolution image — big time," Watt said.
Although free aerial imagery is available from a variety of sources including Google, it is often low resolution, out of date and not good enough to resolve many habitat features, Watt said.
"The bigger picture this is .... they're learning how to work with lots of different types of data and often in GIS classes there isn't much of an emphasis on, 'OK, well how would I go out and collect the data myself?'" Wheaton said. "This is just sort of an illustration ... that it's pretty easy just to take a picture from the sky regardless of the platform. With this (the blimp) they can go out using relatively simple techniques ... and get some (data) to work with."
Digital aerial pictures can also be acquired from satellites, fixed-wing aircraft, helicopters, drones and balloons.
The blimp is pretty simple, Wheaton said. It uses helium and has a kite-like design, so it tracks reasonably well when a student walks along with it tethered to a kit-reel. A camera is placed on an intervelometer, and then the blimp is raised to an altitude that provides the desired trade-off between spatial coverage (typically between 50 meters and 250 meters).
To make the image, the USU graduate students set up 12 markers along the perimeter of the Quad. Students stood at the marker with a rod and used a total station — an electronic/optical instrument used in modern surveying — to shoot a laser toward the rod. When the laser bounces off the rod, the total station calculates the coordinates for that location.
The images are uploaded to a GIS computer program and "the best" images are chosen to make the high resolution image.