Copyright © 2019 by Geographic Techniques LLC • Madison, Wisconsin • All Rights Reserved • Email: Info@geotechmap.org

A Busy Start to Summer

May 31, 2018

Although it's not officially summer yet, we've been busy out of the office and mapping in the field with projects involving drone aerial imagery.  Besides setting up contract UAV missions with DroneBase, Droners.io, and DroneUp, we took part in a well attended Upper Midwest GEOCON Conference in La Crosse, Wisconsin.  And late last month we flew a previously mapped area south of McFarland, Wisconsin, obtained orthophotos and 3D building imagery for the Inn at Wawanissee Point near Baraboo, Wisconsin in early May, and most recently flew the historic Old City Cemetery in Mineral Point, Wisconsin, which initiated our first FAA airspace waiver.  Below are some of the highlights from two of those missions.

 

Inn at Wawanissee Point

Nestled in the striking South Range of the Baraboo Hills, the Inn at Wawanissee Point delivers a lovely venue with splendid views across Lake Wisconsin and the sorrounding countryside.  On a clear day you can even spot the State Capitol dome nearly 30 miles away in Madison!  Wawanissee, pronounced wah-wah-NEE-see, is the Native American Ho-Chunk word for "beauty."  And it doesn't disappoint at that.

 

A couple of years ago we were given the task of updating a map of Wawanissee's hiking trails, mainly used by guests as they hiked and snowshoed on the property grounds.  Armed with an old paper trail map and a high accuracy GPS unit, we set out to map each trail segment within the 40+ acres of mostly forested land and some resored prairie.  Utilizing the recorded GPS routes, along with a bare earth LiDAR digital elevation model (DEM), we reconstructed the map as best we could.  The end result was a layered PDF map showing trails, trail slope, elevation contours, and hillshading.  Now guests can have a choice of hard copy or digital file!

 

As neat as the new trail map was, it still is not highly accurate in terms of the meanderings of certain trail segments, small ponds, and the Parfrey's Glen Creek, within and along the property boundary.  Enter drone mapping!

 

With our UAV, we were able to fly the property during leaf-off, which is a must if mapping trails in wooded areas.  We flew all 40+ acres at 295 feet in altitude, and were able to generate a combined orthomosaic image for most of the property.  Because of the density of trees (even with leaf-off), the orthophotos in a couple of areas on the east and west sides of the property could not be processed correctly, and were left out of the final orthomosaic.  Instead we are working on filling in those areas manually.

 Above:  Constructing trails (red lines) with drone imagery.

 

The result of the drone mapping mission was a success and we are currently in the process of revising the new trail map.  But that's not all!  While onsite, we aqcuired aerial photos specific to the Inn and other buildings, allowing us to experiment with the creation of a 3D model.  We flew the drone in a criss-cross pattern directly above and at oblique angles, in an orbital fashion, around the edges of the buildings, at 90 feet above ground level.  With good success, we were able to derive a 3D image of the building after post-processing of the photos.  A next step would be to obtain more oblique photos at lower altitudes to generate a more realistic close-up view.  However, I wasn't in the mood to fly lower than the trees that day.

Above:  3D model of the Inn processed from drone imagery.

 

Old City Cemetery

We wanted to fly this during full leaf-off, but our FAA airspace authorization did not get approved until mid-May (applied for in early January!).  As it was though, a few trees had not reached full-leaf yet, and there was plenty of treeless space needed to reduce the shadow impacted areas.  Along with flying two flight patterns and combining of both sets of aerial photos, we were able to obtain the high resolution orthoimagery we needed.

Above:  Orthomosaic of the Old City Cemetery, from 150 feet up.

 

Above: Old City Cemetery at 100% photo resolution.

 

The resulting imagery will be used to help locate and identify grave markers for the purpose of cemetery restoration and data base indexing.  One more drone flight will be scheduled for Fall as the gravestone renovation should wrap up by the end of summer. Eventually, the aerial imagery will be incorporated into a publication quality map for an online application and onsite kiosk display.

 

Thanks to Shan Thomas, a local historian and professional archivist, and Deb Emerson, my partner, who assisted with the mapping at the Old City Cemetery in Mineral Point, Wisconsin.

 

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