I’m learning all the time about new methods of forensic investigation.  And, for my readers, hopefully increased understanding of the nature of forensic engineering investigation.  For example, aerial video from a drone of a failure or accident in the built environment has been a real eye-opener for me and my clients in recent years. (Ref. 1)

It struck me recently while walking my dogs in a forest that spring and fall are good times for taking aerial video during a forensic investigation.  Winter too before the snow falls. On a sunny day you can see through the leafless trees to the brightly lit forest floor below.  I can see my dogs off at a distance in the leafless forest why not the forest floor from above?

Even as I draft this blog I’m learning.  It occurs to me that a cloudy day would be even better – no shadows to confuse what you’re seeing on the ground.

For example: I flew over a leafless forest in the spring during a road safety assessment that included a staged road accident for the first time and got excellent aerial video.  You could see a piece of gravel the size of a golf ball from 100 feet.  The video was a dispute-resolution maker.

To be upfront with you though, it was later seeing my dogs running in the leafless forest that made me realize why I got good aerial video during the road assessment.

Another example: I had another case, a fuel oil contaminated site, that was in a dense hardwood forest that was a prime candidate for this type of aerial video.  It didn’t come to pass – the case went off on another tack – but I was ready to capture good video through a leafless forest.

Aerial video of fuel oil contaminated sites in recent years has been a game-changer for me in treeless terrain – why not in leafless terrain too?

Why am I telling you this?  Because, if you’re processing a dispute or insurance claim that involves an accident or failure in the built environment, get aerial video of the site.  If there are leafless trees on or near the site, get aloft in a hurry.  COVID-19 is no problem because it’s easy to keep your distance outdoors.

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Well, it finally happened to me early this spring, a deliberately planned aerial video of a site from a drone through a leafless forest. Plus some testing of forest floor visibility through the leafless trees. I couldn’t get on site fast enough.

And, as turned out, unexpectedly finding a surface feature that added to my understanding of the cause of a problem.

The aerial video was all part of the standard terrain analysis of a site during a forensic investigation. You identify the surface features characterizing the site and how these might shed light on the cause of the problem you’re investigating.

(Terrain analysis with aerial video is also used in basic engineering design and construction. For example, a firm I was with in Australia used terrain analysis to select the initial route of a road through a jungle in Indonesia)

Terrain analysis today involves:

1. Checking Google Earth photography of the site,
2. Studying stereo pairs of black and white and coloured aerial photography of the site – taken from 6,000 feet up, and all we had in the past, but still useful today,
3. Looking at topographic and surficial geology maps of the site,
4. Walking and visually examining the surface of the site – the boots-on-the-ground task,
5. Taking eye-level photographs of the site, and, today,
6. Getting and studying aerial video using a drone flying at altitudes up to 400 feet.

(A little aside. If nothing else, drone photography plus eye-level photography gives you that 3D view of your site. We didn’t have that prior to drone photography – only eye-level, 2D views. I’ve hired planes to get aerial photographs of a site in the past but that was expensive and not as effective)

I did all the bulleted tasks during my deliberate investigation this spring plus set out markers – sheets of white paper on the forest floor – to check visibility. Visibility was good through the leafless trees – no surprise. I also set out red traffic cones a measured distance apart to give scale to a drone photograph.

I studied the aerial video of my client’s site and discovered a feature off the site that contributed to the problem on the site. This feature was not visible during the boots-on-the-ground task.

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It’s been an exciting two years as I discovered new ways of getting the most from aerial video taken from a drone:

• Leafless aerial video,
• 3D photography of a site,
• Virtual aerial video of a site
• Staged accidents to assess road safety, and,
• Pre-planning aerial video with Fly Litchi app + Google Earth

I’m looking forward to summer like the rest of you, and I’ll get good aerial video of my sites, but I can’t wait for fall and winter and that leafless view.

Maybe I’ll let my dogs, Lily and Rosie, run free in the leafless forest during a drone flight. They deserve a treat for alerting me to why I get good aerial video in the shoulder seasons.

References

1. A Bundle of Blogs: Aerial video of insurance and forensic sites taken with cameras mounted on drones. Posted October 31, 2019

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada May 31, 2021 ejorden@eastlink.ca)