FME: Boosting Productivity and Accuracy of UAV Data

Posted on Posted in Sponsors, Updates
FMEBlog1Team Guardian is proud to be sponsored by local technology company Safe Software. In addition to their sponsorship, we are part of the FME Grant Program, which provides students with free licences for their data transformation software, FME. We began experimenting with FME at the beginning of 2015 for compiling warped aerial photos into a mosaic, but recently discovered new ways to speed up our overall workflow during the USC 2016 Student UAS competition.   FMEBlog2Our image telemetry is stored in the EXIF tags so that it’s always linked to the image. Using pyexiv2 and Python, we can extract the GPS data into a comma-separated values (CSV) file. Then we use the pre-built tools in FME, called transformers, to transform the data. For example, the CSVReader and VertexCreator let us plot our image capture locations. We did this after our first flight to see our flight path and identify spots where we were lacking in images. One thing that stands out about the data is how it correlates with how high the winds were during the flight. Capturing images at a fixed rate of 1 frame per second, we can identify times that the plane was flying into a headwind, because the dots are closer together. Similarly, the dots are farther apart when the plane was flying much faster over the ground due to a tailwind. This information lets us plan our image capture strategies and plan re-flyovers to get a better view of an area that was missed or inadequately captured. Another thing we were able to do in FME was calculate geographic centroids and surface areas of the crop fields. We used the CenterPointReplacer and AreaCalculator on input polygons to calculate this information. FMEBlog3The great people at Safe Software love checkerboards. To appease the fans, the checkerboard we use can be seen on the right. We use this to calibrate our camera and lens combinations so that we can compensate for any distortion present in the image and produce parallel lines. We would like to again thank Safe Software for their generous sponsorship and for the great tool that is FME.