Catch a Wave and You're Sitting on Top of... Unmeasured Points?

When Rowe Incorporated's Survey Field Technician II Ray Farr began his work day on November 22, 2005, he did not have plans to swim a lap in frigid Lake Michigan.

The EC Levy Company enlisted Rowe's aerial surveying division, Air-Land Surveys (ALS), to perform an aerial ground control survey at the foot of Lake Michigan in Gary, Indiana. The company required surveys of a number of photo-identifiable control points, to accomplish photogrammetric stockpile volumetric analysis. EC Levy holds and distributes enormous quantities of natural aggregates and slag for use in construction, and sorts and stockpiles slag products resulting from various industrial manufacturing processes for distribution to construction sites.

An unexpected sunny day and quick mobilization of the ALS aircraft meant there was no time to place targets at the site before taking the photos. ALS Project Manager, Greg Lemke chose the control points from color aerial photographs obtained on November 2, showing an industrial site adjacent to a calm, blue Lake Michigan. He selected standard photo control points, including power poles, concrete corners, etc. The final point was the hardest to locate, but a position on the seawall at the lake was eventually marked and added to the list.

Upon arrival at the site, Farr found the photo control points were all mostly accessible from the site's roads and trails. EC Levy Project Manager John Yzenas escorted Farr to each point, and carried a camera to document the survey (allowing him to obtain the photos seen here). For the most part, the survey proceeded as expected, but measuring the point at the seawall was a challenge. Rather than encountering the picturesque calm blue waters as shown in the photos obtained earlier, Farr met with an angry, grey Lake Michigan, with waves breaking fairly hard at the seawall.

Ray believed he would be able to obtain the point with good timing, and without being doused in the lake. Unfortunately, his timing was off. The largest wave of the day crashed ashore just as Farr reached the point, sending him toward the shore with a big push. Ray swam for a moment or two, finding his way out of the water, and never letting go of the Trimble R-8 receiver. Undaunted, he changed into dry clothes, and measured several alternate locations to make up for the single unmeasured point.

About the Author

Greg Lemke is a project manager at Rowe Incorporated, a surveying, engineering, planning, landscape architecture, and photogrammetric mapping company, with offices in Flint, Mundy Township, Lapeer, Mt. Pleasant, and Grayling, Michigan. Visit them at roweincorp.com.

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