I continue to be excited about using drone photography during forensic investigations. The engineer and former land surveyor in me loves the wealth of accurate data in photographs taken a few 10s to 100s of feet above a site where a structure failed or a person was hurt.
We’ve always had photogrammetry in engineering – using photographs taken from airplanes flying many 1,000s of feet above the earth to identify and measure features on the ground.- but we get more and better data from drone photos and get it quicker and cheaper. The potential uses are something else:
Use #1: Investigating traffic accidents: An engineering colleague routinely sends a toy drone aloft, a 100 feet or so, and takes a photograph of a traffic accident site that he is reconstructing. (Ref. 1) He sees his site from this angle right away and it guides his investigation as he does his field work. He can also get a print of his drone photo for his engineering report..
Use #2: Conferring with clients: I conferred with a client a few months ago while both of us had a CD of aerial video of his property uploaded on our computers. I had mailed the CD to him a few days earlier. He commented on features on the ground relevant to my investigation of his failure.
In one case he gave the history of the ground at one location – cows drank from a former dug well there in the past – that was important in confirming the depth to the ground water beneath the site. At the time I couldn’t quite believe what i was hearing about the cows and the dug well – there was no evidence of this when I was on site..
Use #3: Getting data on a site: I emailed a drone photograph to a client recently and asked him to identify the location of buried structures on his property. Structures like two underground fuel oil storage tanks (USTs), – which leaked oil in the past – a drilled water well, two dug wells, a septic tank and a disposal field. He did this then emailed the marked up photograph back to me a few hours later. He used Paint, a program on PC computers. It was all so quick and inexpensive.
Use #4; Getting BIG Data:: The height or altitude of the drone above the ground when a photograph was taken has always been of interest to me. Robert Guertin, Halifax who takes my aerial video, found a program that gives a wealth of data on each photograph. The data includes the height of the drone when the photograph was taken, angle of the photo shot below the horizon, bearing of the view with respect to North and the GPS location, all important data in forensic work.
Use #5: Getting low cost data: I get the scale of drone photographs now from the known size of objects in the photographs. Like the length and width of a building or the distance between the lines on a highway. The scale of the photograph I sent to my client a few days ago that he marked up with Paint is 1″ = 40′.
I can check the scale of a drone photograph by setting out ground control before taking drone photographs, like photogrammetry-of-old. Ground control is nothing more than points set out on the ground a known distance apart and height above sea level. I used sheets of white paper to mark points on a site I was investigating in Cape Breton.
Use #6: Photographing hard to get at damage: I recently suggested to a firm who needed an expert that we could record the condition of a damaged wall with a drone photograph. Later I could measure and analyse the damage in detail and get an idea of the cause – measuring like I do now of the ground but of a vertical surface rather than a horizontal surface. No step ladders, staging, labour and lots of expensive time needed. .
Use #7 Replacing expensive site surveys: The drone photograph with a known scale is certain to replace the need in the future for a site survey by a land surveyor, and be far more detailed, less expensive and quicker. Site surveys measure the size, location and elevation of objects and features on the ground. Conventional site surveys can be time consuming and expensive.
Use #8: Seeing a site in 3D: I’m working with Robert to see if we can get a stereo pair of drone photographs of a failure site and using these to view a site in 3D like we’ve always done in photogrammetry-of-old. Software likely exists now for viewing drone photographs in 3D. If it’s out there we will find it and I will use it during my forensic investigations. In the meantime we’re trying to do it ourselves.
(A stereo pair are two photographs overlapping by about 60%. When viewed with a stereoscope – sort of like eye glasses – the site appears in 3D)
What more do you want from simple drone photographs? Name it and the potential for getting it.is almost guaranteed. Honestly, with all due respect, you or your expert would be remiss if you did not get drone photos of your site. Your expert would not be conforming to the changing forensic investigative standard of care.
- A kid’s toy drone can photograph the site of an engineering failure, a personal injury or a traffic accident. Posted September 12, 2018