Pushing the Envelope at Fort Casey State Park

Staging the gear at Fort Casey State Park

I remain fascinated by the possibilities afforded by integrating many different datatypes. With the ever-increasing list of sensors that can be deployed by drones, and my ongoing obsession with LiDAR and terrestrial laser scanning (TLS) my fascination starts to feel more like obsession.

Case in point. With the help of Washington State Parks and Recreation (WSPR) and a long list of innovative technology vendors a team I put together convened at Fort Casey State Park near Coupeville WA to conduct a proof of concept using an impressive array of drone and ground-based sensors. These sensors included 2x DJI M300 RTK drones. One with the Emesent Hovermap, the other with the MicaSense Altum multispectral and thermal camera, a DJI Mavic 2 Pro, a DJI Phantom 4 Pro, a Skydio 2, and a FARO s350 terrestrial laser scanner.

Doing this kind of proof of concept puts a fine point on what inspires me as they, more often than not, result in innovative workflows, and/or on-site discoveries. I passionately want to explore possibilities, determine if there is any interest beyond my own, understand the value of any “eureka” moments, and collaborate with an amazing team.

Joining me in the field were Stephen Mangum and Gabe Median from MicaSense and Nate Smith with the City of Seattle.

WSPR was interested in three areas of the park. Two were specific to original building locations including a lighthouse. The third was an area specific to an endangered plant species known as golden paintbrush.

Historic Photo of Fort Casey and the lighthouse(s) of interest
Golden Paintbrush (castilleja levisecta)

The challenges began with the airspace which at first glance appeared to be impossible. 

The airspace over Fort Casey (red circle)

After corresponding with the FAA about the waiver it turns out the airspace is Class G below 300’ AGL. All I needed to do was to contact Whidbey Island Naval Air Station to ask for permission to enter the restricted airspace (R-6701) and to obtain the permission anyone is required to have to fly drones in Washington State Parks.

Then there was the challenge of unlocking a geo zone so the DJI drones would fly at the location. By default, DJI drones will not fly in controlled airspace. Pilots need to obtain authorization from DJI so the drones will fly. This is a good thing as it prevents non-authorized pilots from flying where they shouldn’t. New to me at the time was DJI’s Custom Unlocking procedure. After two hours of figuring this out in the field on an iPhone with freezing fingers we were flying. Now that I have done a Custom Unlock for 4x drones on site, in real time, it’ll be super-simple next time.

We began with the multispectral and thermal flights. Using multispectral imaging for archaeological surveys is not new and it does not get enough press. I first tried it in Hawaii in 2019 on my NatGeo series, Buried Secrets of WWII and it provided an actual, on-camera discovery of where an aircraft had burned on the tarmac after being strafed during the December 7, 1941 attack. I was confident we could identify locations of former buildings at Fort Casey because plants refract light differently over ground that has been disturbed. I was hoping that the thermal capability of the MicaSense Altum would provide a surprise as thermal imagery often does.

While the multispectral / thermal flights were underway I grabbed my FARO s350 laser scanner and headed for one of the two 10” disappearing guns that are a highlight of the park. Fort Casey was a part of the coastal artillery defenses at the entrance to Puget Sound from the late 19th to the early 20th century. I am a US Army artillery veteran so this site was of particular interest to me. That said I wanted to have TLS data to integrate with the LiDAR of these amazing artifacts.

The business end of a 10″ disappearing gun at Fort Casey

After Gabe and Stephen finished the multispectral and thermal flights – which the MicaSense Altum can do at the same time – I flew the LiDAR with the Emesent Hovermap followed by Nate and I flying the photogrammetry missions with Nate’s Phantom 4 Pro and my Mavic 2 Pro. As we finished the photogrammetry flights late in the day the sun finally appeared. Nate and I jumped at the chance to shoot some video of the sunset over the park.

The data took me a few hours to post-process. I used Pix4D & Pix4Dfields for the multispectral, thermal and RGB), Emesent & CloudCompare for the LiDAR, and FARO Scene for the TLS data. Integrating all of these datatypes together in ESRI ArcGIS Pro, I have to say, was all new to me. Chris Andrews and Sean Morrish from ESRI were incredibly generous in showing me the amazing capabilities of “Pro.”

As I had hoped the multispectral and LiDAR data showed the outlines of former building locations so right away I knew the project was a success. Right angles do not occur in nature. Identifying the endangered Golden Paintbrush plant is absolutely doable but we’ll have to wait until they are in bloom to get the results WSPR requires. It’s really a simple process. Enter in the “spectral signature” of the golden paintbrush blossoms and they will jump out of the multispectral data. I am really looking forward to doing this work in 2021.

Multispectral and LiDAR data – note right angles and linear anomalies

The thermal imagery didn’t provide any breakthroughs but it is still a valuable asset in terms of data layers. The obvious anomalies are the nice warm cars in the parking lot. MicaSense pairs multispectral with thermal for precision agricultural purposes. The thermal imagery is particularly useful for understanding irrigation. Adding that to the overall health of crops that multispectral imaging can provide and it’s a game changing one-two punch in terms of tech for agriculture.

Warm cars at the Fort Casey parking lot in the thermal imagery

The LiDAR and the RGB (photogrammetry), in this case, provides all of this data with elevation . . . the magical context the 3rd dimension provides. 

Fort Casey 3D LiDAR data
Fort Casey 3D Terrain Model with Contours

Draping multispectral and thermal data over terrain was a personal goal as I had not seen this done before.  That’s not to say it hasn’t been done before.  ArcGIS Pro made quick work of this.  Furthermore, the TLS data can be merged as well in Pro.  I had no idea.  ArcGIS Pro is loaded with capability for these kinds of projects. I continue to be blown away by Pro.

The data comes to life in ESRI ArcGIS Pro

After presenting all of the data to WSPR it was pretty clear there was excitement.  I am thrilled that the WSPR scientists and researchers agree that the data will provide value in ongoing archaeological and botanical research at Fort Casey.  Best of all we are talking about additional projects at more parks here in my new home state of Washington.

Multispectral and LiDAR data show numerous anomalies

I owe a huge debt of gratitude to WSPR, Emesent, MicaSense, ESRI, Pix4D, FARO, DJI and of course my friends & collaborators Stephen Mangum, Gabe Median, Nate Smith, Callum Scougal, Jeremy Sofonia, Chris Andrews, Sean Morrish, Jerry Hardy, Scott Diaz, and Rob Miller.  None of this would have been possible without the vision, cooperation, passion, and generosity of these great folks and their organizations. Thank you all so very much.

A 4 minute video of the project is HERE.

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