Surveying Services for Dana Colbert Park Improvements
Dana Colbert Park is an approximately 50-acre public park in Savoy, Illinois. The park has some unique features including a large pond surrounded by a trail and a steep hill designed and constructed as a sledding hill. The City hired MSA to survey and design updates and improvements to the park. Because of the open nature of the park with little tree cover and the grass mowed short, it made for a good candidate for a photogrammetric survey conducted with a drone.
Photogrammetric survey requires aerial photography, but to tie the photos to the location, best practices are to set ground control that can be observed by the drone. Because this project required a survey of the overall boundary of the park and there were a few areas requiring traditional survey, it was practical for surveyors to set ground control while taking care of the other tasks that require boots on the ground.
The drone flight conducted for this approximately 50-acre site collected nearly 400 photos in 20 minutes’ time. The photos were then processed relative to the local ground control, allowing for the creation of a few types of deliverables. Geo-referenced images are some of the most valuable deliverables. These are current photos captured at the time of flight, geo-referenced to match all other geo-correct data that has been acquired or created. Designers and clients can look at a picture and see in detail the precise conditions at the time of the flight. The imagery can be referenced relative to any other survey data, design data, or GIS data that may be available. From the imagery, site changes can be detected that wouldn’t necessarily be possible utilizing other, less current, imagery sources. Utility locates called in for the project, for example, can often be seen and mapped, and the geo-referenced images help answer questions that arise when reviewing survey CAD data.
Additionally, photogrammetry can be used to create a point cloud from which topographic survey data, including surfaces, can be extracted. Once the photos have been processed and tied to the ground control, a point cloud can be generated. The point cloud can be classified into different data types such as buildings, vegetation, above-ground utility structures, and surfaces. These classifications act as a filter to aid in cleaning up the data, and once filtered, the data can be saved or converted to another type of file, like a surface model that can be brought into CAD for design.
The efficiencies created by photogrammetric survey speak for themselves, but the value of the additional data captured by the photos may be where a drone surveying truly shines. Traditional survey data is often the most practical, if not the best way, to capture the most accurate survey information, but it cannot always explain things the way a picture (or 400 pictures) can.
MSA’s team of surveying professionals is dedicated to researching and testing all the latest survey tools while also utilizing traditional survey methods to provide the best possible data to our designers and clients.
Client
Village of Savoy
Location
Savoy, IL
Services Provided
Contact Project Lead
John Dewey, PLS
Senior Project Surveyor
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MoreSurveying Services for Wisconsin STH 13 Wayside Revetment
MSA was asked to survey a challenging 900-foot stretch of shoreline along the south shore of Lake Superior in Port Wing, Wisconsin. The shoreline has experienced severe erosion over the last 40 years due to wave and ice impacts upon the highly erodible clay soils in the bluffs. Recent high-water levels of Lake Superior have also been accelerating bluff sloughing, threatening to undermine a scenic wayside overlook along State Highway 13.
The project provided unique challenges as portions of the site were inaccessible and unsafe due to erosion. Additionally, deposits of driftwood and debris littered the shoreline, making it difficult to survey by traditional manned methods. MSA also needed to gather modeling aspects of lands underwater. This combination of a large survey area and need to collect data of varying depths made it impossible to locate with GPS or a robotic total station alone. Even though the site and terrain were complex, MSA was able to leverage cutting-edge technology and a variety of tools to be successful.
Topographic digital terrain models and surface data were created using a combination of traditional survey methods and an unmanned aerial flight via drone utilizing LiDAR. LiDAR (Light Detection and Ranging) is a remote sensing method used to examine the surface of the earth. Light is emitted from a rapidly firing laser, and as the light travels to the ground, it reflects off things like buildings, vegetation, and bare ground. The energy returned, and the time it takes to be returned, is recorded to determine surface type and then categorized so that it can be filtered later. The unmanned aerial vehicle (UAV) is also recording the altitude, GPS location, and orientation so that the LiDAR data can be used to create a three-dimensional surface of the site — in this case, roughly one-half a mile of shoreline frontage along Lake Superior.
With flight parameters set, pre-flight checklists completed, a pilot in command and visual observers ready, MSA efficiently conducted multiple flights to collect over 100 million data points and nearly 2,000 orthophotos to process, filter, and build a detailed surface model of the site.
Contours generated from point cloud data from LiDAR.
MSA also gathered bathymetric data for the lakebed survey utilizing SonarMite — a small, portable hydrographic echo sonar system — to map the lake floor. The SonarMite was towed behind a motorboat in slow, serpentine patterns, to cover the half-mile area offshore, connected to a GPS unit to map the depths with optimal spatial accuracy. This lakebed survey was done to complement the survey of 1,500 feet of shoreline already underway.
After data was collected from both the shoreline and lakebed, MSA meshed both the terrain and bathymetric data together to create one seamless surface model, confirming confidence in the data through standard quality control methods. The result is a comprehensive reality capture of both surface and lakebed topographic data to inform shoreline remediation work at this complex project site.
Meshed digital terrain model showing both contours and as a Triangulated Irregular Network (TIN).
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