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Projects Details

Mapping Emergent and Riparian Vegetation’s Response

Report Link

Fall 2016

Executive Summary

EDC, Inc. scientists partnered with Dr. Shon Schooler (University of Wisconsin- Superior) to map vegetation at the Lake Superior National Estuarine Research Reserve’s Sentinel Site on the Pokegama River. Dr. Schooler is measuring plant communities at permanent vegetation monitoring plots established as part of NOAA’s Sentinel Site program. He expects the location of these communities to shift as lake levels change over time. We are using EDC’s UAV to collect high-resolution, spatially accurate imagery to map important features along this river corridor. We were also interested to see if UAV imagery could be used to identify and map ash trees along the riverbanks. Ash tree mortality is expected to increase as the emerald ash borer, an invasive beetle, moves into the area. Dr. Schooler is currently assessing the ecological consequences of this invasion.




Locations of UAV photo points along a series of flight lines for one of the image acquisition areas.

Project Description

Data are currently being analyzed.



Three of the mosaicked images shown on a Google Earth B&W aerial photograph.

A zoomed in section of the mosaicked image.





A zoomed in section of the mosaicked image showing the project boat.

Another zoomed in area of the mosaicked image showing late season, floating leafed vegetation and algal mats. The blue line represents an on-the-ground length of 1 m.

Approach

We were interested in collecting late season, leaf-off imagery along the Pokegama River. We operated the UAV at 200 ft and 300 ft AGL varying the image side- and overlap to obtain the best results. At 200 ft AGL, pixel size was 1.0in (2.54cm) and at 300 ft AGL it was 1.6 in (4.06 cm). We covered the study area with six UAV flights, each under 20 min long, that ranged in area from 5.73 ac (2.31ha) to 36.78 ac (14.88ha). Using the imagery alone (i.e., no ground control points were used) spatial accuracy (RMSE, Root Mean Squared Error) ranged from 1.6m (X=1.2m, Y= 0.9m, Z = 0.5m) to 2.5m (X=1.2 m, Y=1.7 m, Z = 1.4 m). We determined that the spatial error was acceptable and that vegetation mapping, using GIS, could proceed.



Example of 3D model, created from imagery alone, that shows tree architecture. Project boat and three targets are also visible in image.



Dr. Schooler operates the UAV from the project boat. The small launch footprint of EDC’s UAV make it ideal for this type of work.