Researching High-Flying Ways to Produce the Most Accurate Maps




​​In summer 2019, Fresno State graduate student Jacob Lopez sat in a cool, dark engineering lab on campus analyzing digital photos of the Sierra foothills captured by unmanned aerial vehicles (UAVs). 

Lopez, a civil engineering major focusing on geomatics, is one of three students working on an aerial mapping research project with the California Department of Transportation. In mid-June 2019, he presented the project at a conference in the Netherlands. 

“We’ve been given these resources to help Caltrans really take the time to understand the many aspects of this new technology,” Lopez said. “Everyone’s starting to use it now.” 

Caltrans approached Dr. Riadh Munjy, professor and chair of the Department of Civil and Geomatics Engineering in the Lyles College of Engineering at Fresno State for help researching and determining the best practices using UAVs for high-accuracy mapping. The university’s geomatics engineering program is the first four-year, nationally accredited comprehensive program in the nation. 

The state agency needs to establish guidelines such as which type of UAV to use—one with a fixed wing or a rotary system—how to fly it, what type of camera to use and ground control placement, Dr. Munjy said.  Specifically, how it can be done and what type of equipment needs to be used, he said. 

The civil and geomatics engineering department and Caltrans have a long history of working on photogrammetry research together—at least 30 years with Munjy. Photogrammetry is the science of taking measurements from a photograph to create a map, a drawing or model. 

The findings from this three-year project will offer instructions on how to use UAVs in surveying and mapping. The findings also can be adopted by any agency producing photogrammetric maps. 

​Munjy and his team at Fresno State contracted private UAV pilots to perform three test flights over the San Joaquin Environmental Range, 4,462 acres of annual grass and oak-pine woodland off Highway 41 in Madera that serves as an outdoor laboratory for students. In fall 2019, the team planned to conduct more test flights over a Cal Fire yard at the University of California, Davis. 

For many years there was a disconnect between technology and its application. Drone manufacturers didn’t know how photogrammetry worked, said John Erickson, chief in the Office of Photogrammetry and Preliminary Investigations for the Division of Engineering Services at Caltrans. 

Traditionally, survey crews of two to three people are sent out to do topographic surveys of small areas. Planes are used to capture aerial photographs or lidar images using lasers of large areas. ​​​​