The Agribotix team is in New Zealand, flying our UAVs over Tasman Glacier to help researchers at Victoria University of Wellington make a digital elevation model of the glacier. Today, we flew the twin boom Sky Hunter over 100km in transects across the glacier. We've mounted a downward facing camera in the fuselage, which takes photos every 3 seconds. Using these photos, and programs such as Agisoft Photoscan Pro, we can construct an accurate 3D model of the glacial surface, useful for a variety of research applications, including estimates of glacier velocity and the change in glacier volume over time.
Read more about our flights today, and check out our progress at: Glacier Flights
Comments
@Tom. Yes, the gimbal game is quite interesting. My experience with photogrammetry is that "subduing" roll in fixed-wings is important. Modern software can compensate for a lot, but I believe one will achieve more consistent accuracy if ones camera is as near nadir as possible. I've been experimenting with brushless gimbals using alexmos boards and I'm really impressed. Pitching my gimbal around in my office I can stay within a few tenths of degree of Nadir. The Skyhunter has room for both roll and pitch, but I'm thinking I'm going to focus on a very simple and lightweight roll axis gimbal, integrated with good vibration dampening. Right now I'm working on making a mount that hangs from the canopy area of the Skyhunter. I'm hoping to start flight testing in the next week (mornings are still -25C !!).
In regards to software I will be testing a slew of software: agisoft, Correlator 3D UAV by SimActive, BAE Socet GXP and even some of those online processing tools.
I'm assuming crashes, so I have a few extra Skyhunter kits in the ready!
@Michal Rus. The details of our Sky Hunter build are listed here: http://agribotix.com/blog/2014/3/28/sky-hunter-components
@Michal Rus. We reviewed the flight logs and determined that the crash of our Sky Hunter was due to a motor failure, not a downdraft that we first thought. Although it was extremely turbulent near the crash site. I'll be putting up details of our build on the blog at Agribotix.com in a day or two.
@Peter. No, our camera was not on a gimbal. Besides not wanting to carry the extra weight it's not clear that a gimbal would improve the ultimate image mosaicking and orthorectification. I'm not all that familiar with the mathematics of it, but Brian Anderson, our NZ glaciologist is into the guts of the software -- and he gave an equivocal answer to that question.
We are using the Agisoft Photoscan Pro software and Brian uses Visual SFM (VSFM has a non commercial license clause so Agribotix can't use it). The images are still being crunched through the computers now so we don't have a head-to-head comparison between the two products.
Yes, the Sky Hunter is a sweet platform for this project. It tracked the mission like it was on rails. Unfortunately we had a motor failure on our 6th mission and the plane is now resting on an extremely unstable moraine wall above the glacier. Recovery of the plane would playing Russian roulette so it's going to stay there. Fortunately we have a RV Jet with us as a backup.
We are posting more details on the blog at Agribotix.com.
"As we tried to steer away from the cliff and give the drone full throttle in an attempt to gain elevation, the drone instead started spiraling down towards the surface. Too soon, it became clear that we had crashed into the ground. "
This happened to me as well with Bormatec Maja 1.8m wingspan. I lost the plane due to stall speed and after pulling the throttle full it went to spiral and down crashed.. I suspect this is the same or similar to your case..
Else I have now Skyhunter too and after 6 months of building and configuring I'm almost ready for testing. It would be nice if you could share your setup details, mainly motor, esc, propeller, battery and payload configuration. I have 4 cameras onboard, 2 x 5000mAh 4S zippy compact, NTM 35-48 900, 60A esc, Pixhawk, FPV and OSD, 3 servos, Graupner RC which gives me 3.5 kg MTOW which should be max for this frame. I do not use gimbals for 2 of my cameras but would be nice to see if it makes difference for verticals (with and without). I use 2 x Canon SX260 for verticals, one of them is hacked by MaxMax for NDVI. So I have RGB and NDVI of the same flight without the need to swap cameras on the ground. The other 2 cameras are for FPV and FULLHD video record. I have also custom 433mhz antennas to get better range for telemetry. Then I use also 2 x patch antennas for 5.8ghz FPV and diversity receiver just arrived so I will do lot of testing in upcomming weeks. I have now a range of different 12x6 and 10x6 propellers and not all of them seems to be pusher type so I have to test again. So what's your setup then ? Is 10x6 giving you more flight time ? Are you using Pixhawk ? And AUX pin with hacked upcurrent for RC-USB cable to control camera shutter ?
I'm specialised in archaeological UAV applications but now I want to do precision agriculture too as the nature of my workflow is essentially the same..
Thanks
Michal
Slovakia
Awesome! My Skyhunter is sitting built on my table and getting ready for some similar mapping projects in the Yukon. Just waiting for better Spring conditions to get going. Did you use a gimbal system? I'm currently have a 2-axis servo system and am working on a 1 or 2 axis brushless gimbal using alexmos. I think the Skyhunter is a very good platform as a mapping beast!
What software are you going to use to generate DEMs?
Looking forward to following your project and results.
Thanks for the feedback. Hugues, we'd be happy to share our mission scripts and flight maps -- we'll put them up on our website and send you a message when they're there. And Gary, thanks for the heads up about the wiki page! We sadly lost one of our drones today (http://agribotix.com/blog/2014/3/21/sky-hunter-down), but we should be back in the saddle soon.
Nice project
Great post, Randy has just started the mapping wiki page with the help of the last T3 round crew http://planner.ardupilot.com/wiki/common-3d-mapping/
This is great to learn from. Can you share your auto mission scripts? And screenshots of your flight maps?