Hi and thanks everyone for your interest. I’ve gathered my thoughts and am putting them down here. It’s a fair bit of detail straight up, I figured I may as well just get it all out there.
As mentioned I am planning a flyover of two properties to develop a carbon farming project. The site is 2000 Ha so I was looking at a Cessna flyover with a GoPro clone. The terrain is relatively flat with a couple of hills and a number of creeks and gullies.
I know after my reading of the posts and comments here that there is a rolling shutter problem with cheap action cameras, limited overlap and a moving camera. However I’m wondering if the problem can be resolved using the 2 layer flight plan from following recommendations from this post (Optimizing flight planning for calibration (or Self Calibration of Cameras from Drone Flights, part 4) – Smathermather's Weblog).
The approach would be to attach a 20 MP Campark X30 GoPro clone under the wing with a triple suction cup mount.
The camera can be controlled from the cockpit via an Android App to take 10 sec time delayed images. The resolution would be reduced from the 20 MP max to 13 MP.
I was planning to update the GPS data back in the office from a Android phone running the GPSLogger app (3m accuracy). The phone would be time synced with the camera and located on the dash of the plane . A consumer grade Garmin GPS would also be on the dash in order to have a cross check/backup. I have the option of setting up GCP’s.
The flight would be on a bright sunny day timed for midday at 120 km/hour (33m/sec). At this stage, if I get a clear ortho image with +/- .5m accuracy I’ll be very happy on my first run.
I’ve configured QGIS Flight Planner with the cameras current settings with a 30% frontlap, 60% sidelap, and a camera tilt of 80 degrees. The direction of the second layer of images would be offset by 20%.
This plan can be easily changed if needed. e.g. 80% sidelap. The Layer 2 config is shown below.
The two output layers from QGIS Flight Planner look like;
Layer1(Pink); requires a minimum of 95 images 1410m apart at ASL 903m.
Layer2(Red); requires a minimum of 571 images 475m apart at ASL 767m.
The best settings of the camera that I’ve found from taking photos in full sun are; Photo Resolution = 13M, distortion correction = On, ISO = 100, White Balance = Sunny, Exposure = 0, Sharpness = High , FOV = Narrow
Note: These settings translate to the following on the images properties;
Width: 4160 Pixels
Height: 3120 Pixels
Exposure time 1/3120sec
Focal Length 18.0(35mm film), 2.3(lens)
Sensor Size 8.46
Image size is 5 MB
This project will be run on a shoestring budget and the question at the moment can be boiled down to go/no-go. If its “go” then there are two additional questions in my mind;
- Are there better/recommended settings for this type of camera to work with WebODM?
- Can this flight plan be improved to overcome the rolling shutter issues at 120km per hr?
Thanks again for your consideration.