At the UMass Amherst campus we regularly use UAS to conduct surveys of key infrastructure; whether it be to monitor and document stages of new construction on campus or to survey and inspect existing infrastructure. One of our more recent additions to our array of capabilities is the capacity to develop thermal orthomosaics from long-wave infrared (LWIR) imagery. This can help us map heat sources and thermodynamic processes of buried infrastructure, or look at heat loss in structures.
In a recent survey project we surveyed roofing of some campus buildings to inspect for suspected leaks. In general, if water leaks into a roof if can compromise the insulation of the building and conduct heat more readily. In the winter time when the outside temperature is significantly cooler than the inside temperature areas of compromised insulation will show up as relatively hotter than the surrounding area on a surface because it is conducting the heat from the inside to the outside more readily.
Working with thermal imagery can be especially tricky for several reason. Unlike many other types of aerial imagery which captures images of reflected radiation, thermal images are images of emitted radiation, that is to say radiation emitted by warm objects. This radiation depends on the emissivity of a material, which is the proportion of how much energy it emits at a given temperature compared to an ideal “black-body” radiator. Consequently all images have to be adjusted and tuned to look at specific materials, and be tuned to compensate for reflected radiation from the background (which is the sky in this case), as well radiation signal loss through the atmosphere due to attenuation by both water and carbon dioxide.
Additionally, just as with orthomosaics constructed from red-green-blue images, we use ground control points (GCPs) to help constrain the reconstruction of LWIR thermal orthomosaics. GCPs for thermal surveys need to be designed slightly differently; while GCPs used for surveys in the visible bands need to have “color” contrast with respect to the ground on which they are placed, GCPs placed for thermal surveys need to have either temperature or emissivity contrast with the ground on which they are placed.
The use of an RTK GNSS receiver or other accurate survey tool allows us to measure this GCPs to within a few centimeters, and consequently a similar level of accuracy can carry over to final data products. This is important so that our thermal orthomosaics can align accurately with RGB orthomosaics, as well as other data layers such and surveys that might show areas of infrastructure; this enables us to relate the thermal signals we see to specific structures or features measured by other means.
City and regional planners have the daunting task of developing a vision for the future of both the physical, aesthetic and cultural feel of an area. This often involves engaging multiple parties that have a stake in that future, identifying convergent or divergent needs or desires of those stakeholders, identifying themes within those needs or desires, and developing not just one potential plan, but a multitude of plans that can be considered in comparison. Continue reading “Using the Trimble R10 with Drones to Develop City Models for Professional Planners”
Drone flights were in support of a project lead by a Collaborative Adaptive Sensing of the Atmosphere (CASA) research team in the UMass Amherst Electrical and Computer Engineering Department (http://www.casa.umass.edu/). The team, led by Krsztof Orzel and Apoorva Bajaj, wanted to test the ability of their weather radar system to track and identify UAS targets. The Trimble ZX5 hexacopter was flown in a variety of patterns and altitudes to test the limits at which the drone could be detected. The drone was also flown simultaneously with the a DJI Spreading Wings 900 (that had been modified with a PixHawk for its flight controller) which was flown by another independent pilot. The simultaneous flights allowed the opportunity to start to get a sense of how easily the weather radar could de-conflict the two signals from each of the drones. By comparing the radar signal log to the flight logs of the multirotor UAVs, the team aims to gain a sense of the accuracy and precision of their radar instrumentation, and in the future they aim to tweak the signal processing algorithms to yield better results. Continue reading “UMass researchers using radar to detect drones”
Enhancing UMass’ capabilities above ground, we recently added a Trimble ZX5 drone to our equipment. This will among others support the new UMass Air effort and allow students and faculty to explore air-based surveying and aerial imagery.