Portable Mapping Pod Update
As I have alluded to in earlier posts I have been working on a portable mapping pod system, over in my day job at Aerial Acquisitions. Designing, building, testing and refining the pods and sensors has been a long and on-going exercise. So it has been great to see the first versions of our systems taking flight around the country on various projects.
One of these projects was a forestry project in the wilds of Tasmania, which is turning out to be a great test of the system and our mapping pod concept. Now I have to admit to being a little nervous to sending a system to Tasmania, far away from technical support on one of its first major hit outs. Aerial survey tends to have an amendment to Murphy ’s Law and that is that if something can fail it will, and the likely hood of failure is increased with distance from home base. So far Murphy has been kind and only thrown us two small issues, both easily resolved.
Why Tassie is a good test for the mapping pod
Tasmania is a difficult place to capture imagery, due to really variable weather and lots of cloud cover. As the saying goes, if you don’t like the weather in Tasmania just wait an hour! Constant cloud makes capturing imagery difficult, and you may only get 2-3 cloud free days per month to capture imagery. Often you may only get ½ day clear either in the morning or afternoon. So this presents some interesting problems for image capture. It’s not economically viable to have a survey aircraft and crew sitting on the ground for 28 days per month watching cloud drift past from the comfort of a bar stool at the local pub (been there!). But to take advantage of the short gaps in cloud you need a local aircraft on the spot that can be mobilised quickly. So enter the portable mapping pod strapped to a local aircraft, using local aircrews that know the weather.
I thought I would briefly outline our methodology of our project in Tasmania, as its fairly typical of how I see our pods operating once released into the wild.
Getting there – Mobilisation
A major design feature of our portable pods is that they had to be completely portable. So we designed them to fit into a small pelican case, roughly the size of a small suitcase to make travel and shipping easy. All packed in its case ready to ship the system only weighs around 8kg, allowing it to be taken with you as luggage on a commercial flight, or sent via mail or courier. For this project my business partner and I opted to jump on a commercial flight and take the pod with us as luggage. As we wanted to train some local pilots on the system and oversee the initial install on a local aircraft. Now that we have a local aircraft and pilots lined up, for any future projects we will simply ship the pod down.
Being able to jump on a commercial flight with the system offers large savings over having to ferry our company survey aircraft down. I estimated that to ferry our company Cessna 172 from Sydney to Tasmania would have been around 15 hours return depending on winds and cost around $8k AUD including pilot wages and expenses. In contrast to this two of us were able to fly down on a burner for less than $1k. For future projects the savings are even greater as I can simply ship the system to Tasmania for a few hundred dollars. If I were to take on a project in Perth or Darwin the savings in mobilisation would be even greater.
Fitting to a Local aircraft
For this project we were able to find a local Cessna 172XP which we were able to fit our pod to in around 40 minutes. The 172 XP is a nifty aircraft it has a bugger donk than the standard 172, it also has a constant speed propeller and is fuel injected giving slightly better cruise and climb performance than the standard 172. Normally the increased performance of the XP would not really matter. But for this project a number of our coupes need to be flown at close to 10 000 ft above sea level, so the increased climb performance will come in handy.
We found a local engineer who was able to oversee the fitting of the pod in around 40 minutes to the aircraft. Fitting of the pod is really simple. Firstly the co-pilot step is removed from the landing gear leg by removing 3 bolts. Our pod then simply fits in place of the step, and the 3 bolts are re-fitted. Lastly a few cable ties are used to secure the single cable from the pod into the aircraft cabin. A single cable runs out to the pod from the flight management system in the aircraft cabin, this triggers the camera and records when the camera fires.
One of the reasons the system is so simple to install is that it does not require aircraft power to operate. Our mapping pods were designed to run independent of aircraft power. Once you start running cables with power out along wing struts, or landing gear legs engineers get understandably nervous and this starts to greatly complicate things.
Flight Management System (FMS)
Our systems are designed to be easily operated by a single pilot only, with no camera operator / navigator required. After hours and hours of flight testing we have finetuned our cockpit set up, to a simple system that works. This comprises of a small touch screen tablet that runs the flight management software, mounted in the eye line of the pilot. Tablet mounting is flexible to allow individual pilots to set up the system to their individual preference and allow easy access.
Once airborne the FMS acts like a big video game and gives the pilot guidance to fly the project. It also fires the camera at pre-planned photo locations, and records a GPS event for each photo. Because the camera is buried in the pod away from the pilot’s sight, the FMS also gives a confirmation on the tablet screen that the camera has fired. This saves the rather expensive exercise of the pilot flying around for hours with a camera that’s not working.
We were able to train our local pilot on our system who had never flown survey before in around an hour. After flying a number of test runs over the airport he was confident enough to head off into the wild blue yonder and have a go at some real projects. He has now flown over 30 small forestry areas without issue and has commented on how he feels comfortable with the system.
Once the aircraft lands the data card is removed from the Nikon D800 camera, and uploaded to me via the interweb for processing in Agisoft Photoscan. For our Tasmanian project the client only requires simple othrophotos to update their GIS, and our pods are proving ideal for this application.
Having been around in the good old days of aerial survey when we still used 250 ft long rolls of film, it still amazes me how seamless the whole process is now. When I started in aerial photography, turning data around quickly meant processing the film myself in a small tin shed on the airfield after landing. Once the film was processed I would then rushed the still wet film to the office so they could start on the photogrammetry overnight. This wasn’t too bad in winter but that tin shed was not much fun in summer in 36C heat!
I have to say I think it’s pretty cool that I can be remotely managing an active aerial survey project from a different state without leaving my office. Using our portable mapping pods and a local aircraft and crew to capture the data is proving to be very effective. There is still some fine tuning to be done on transferring data but overall it’s working really well. Next step is to integrate in some more sensor options, with multispectral and thermal coming soon.
What’s really exciting for me is that using portable mapping pods carried by local aircraft has the potential to slash data capture costs over traditional methods, delivering data at bargain basement prices. I see real potential here for our portable mapping pods to be used for a range of projects not just commercial mapping work. I would love to see some of these systems deployed on environmental projects, rapid response events, and humanitarian projects.