In February of 2019, the Bi-State Regional Commission (Iowa-Illinois) contracted Surdex Corporation for orthoimagery, lidar data and topographic mapping.
The 16 participating members of the Commission included several municipalities and counties along the state border area.
The project was complex due to the variety of end products and specifications for final deliverables from each client; seasonal flooding and the limited leaf-off, snow-free acquisition season in Iowa and northern Illinois introduced another layer of difficulty. The challenge, therefore, was to come up with an acquisition plan agreeable to all 16 participants, realizing that all acquisition could not be completed according to the original plan.
The initial acquisition was set for spring of 2019; however, there was significant flooding in the project area during this time, obscuring the ground (which would render the imagery unsuitable). The usual remedy would be to hold acquisition until the floodwaters have receded, but because the region has an extremely limited acquisition season, pushing back collection could jeopardize the entire project. After discussing the matter with the project participants, it was decided to acquire imagery for the entire project in the spring as planned and return at a later date to re-fly the imagery in the flooded areas.
After the imagery was acquired and fully processed for the full project area, it was sent to the clients per the original schedule. Participating Commission members marked the flooded areas using shapefiles and sent these to Surdex. Once the flood waters receded, imagery re-flights were conducted, and this new data was processed and sent to the appropriate clients. All lidar data was captured and processed at this time as well.
The participating Commission members were able to receive as much data as possible in the shortest timeframe possible. All 16 project participants were consulted at every step, including development of these critical adjustments to the original plan. This innovative collection / re-flight approach enabled successful completion of the project. The scope of acquisition for this project is detailed in the table to the right. Derivative products for the lidar data included a Bare-Earth Digital Elevation Model (DEM), classified lidar LAS files and 1’ contours, among others.
Author: Cornell Rowan, CP, Project Manager at Surdex Corporation