Aerial Mapping with multicopter

Hello all, I've been toying around with the MikroKopter Hexakopter as a tool for aerial mapping and photogrammetry. After a few weeks of learning the ins and outs of the system, I finally had some time on the weekend to test the system for mapping.

In short, we placed Ground Control Points (GCPs) around a man-made ponding area at roughly ten meter intervals (~40 x 30 m in total area). The GCPs were shot in with a deferentially-corrected GPS (~0.1 m horizontal and ~0.2m vertical resolution) and with a Total Data Station (>0.03m vertical and horizontal resolution). We then flew the Hexakopter at 40m above the ground surface in an east-west grid pattern with a photograph being taken straight down every 10 m or so. The camera used was an off the self Canon A540.

The photographs were processed to remove most distortion and dropped into a photogrammetry program. A 0.05 m resolution DEM and 0.02 m photomosaic was created from 22 images. It took about two hours to collect the photographs, and shoot in the GCPs with both the DGPS and TDS. Processing of the imagery was nearly flawless and took about two hours as well. This time can probably be reduced to an hour or less.

Compared to doing this same process with a kite or blimp, I am very impressed with the Mikrokopter (and multi-copters in general) as a platform for high resolution, low altitude mapping. Let me know what you think.

Over the next few weeks, I'll be testing the same process in at a couple of archaeological sites in the southwestern US. I'll share some of those results when they are complete.

Can't wait to play with the truly opensource Ardupilot!

-Mark

Paul, I'm still trying to figure that out but it is really a function of the resolution of the data you need. The higher the craft is flown, the more area you can cover with each photograph and the faster you can travel between points and still get good overlap with the images. The higher you fly the less resolution you've got in both the DEM and photomosaic.

I'll be flying at a large archaeological site that is 1.1 by .4 km in size later this summer. That should really test the boundaries of the machine and technique. This should give the best evaluation of the process using the hexakopter. I've also got a Hawkeye setup with ArduPilot. Hoping to see how it does also.

Using the hexakopter there really aren't any bottlenecks (other than the learning curve of LPS which is very steep) in the post-flying workflow. The largest bottle neck is the flight time (about 18 minutes) and self-imposed limitations of the Hexakopter (maximum flight radius is 254 m).

If you compare the time (and cost) it would take to collect the same sort of data with LIDAR, from a manned aircraft, or via traditional ground survey, it's very and fast.

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Gary Mortimer June 15, 2010 at 6:34am

not above 400' ;-)
Mark Willis June 15, 2010 at 6:17am

@Rory, it might be pushing it to map a 40 acre area quickly with a multicopter. What is your typically flying height?
T3

Rory Paul June 10, 2010 at 8:31am

@Abey

I believe that quads although slower and with less endurance will offer a more flexible platform for mapping applications. The fact that they can stop and hover in an exact location to take the required imagery makes it an interesting proposition (definitely for small scale farms).
abey June 10, 2010 at 7:22am

@Paul: could you elaborate on why your thinking of going from the CropCam to quads for this type of agricultural work?
T3

Rory Paul June 10, 2010 at 7:18am

Mark

Thanks for the reply. The reason I ask is that I am using a fixed wing UAV (CropCam) for agricultural work and I have been thinking of trying a quad.

My concern is the endurance of the platform typically a 40 acre shoot may have a flight path of 9000 - 12000 meters at 5-6 cm resolution and 75-100 images with 50% overlap. A flight of this type would only take 25 or so minutes.

Good luck with your mapping project please let us have an update!
Mark Willis June 10, 2010 at 5:59am

I also have PhotoModeler Scanner and use it in close-range photogrammetry on rock art sites. Unfortunately, it will only work on very limited numbers of stereo pairs and crashes often. Photomodeler Scanner is great if you only have a handful of images to work with.
OpticalFlow June 9, 2010 at 9:26pm

I'm not familiar with Leica Photogrammetry Suite but I was wondering whether this could be done in PhotoModeler Scanner? This software package would still be more expensive than the Hexacopter itself but maybe it is cheaper than the Leica package (for which I haven't seen a price tag). It would be nice to see an open-source photogrammetry package but it would be huge task.
Mark Willis June 9, 2010 at 12:40pm

I just noticed a storm had knocked my server offline. It's back up now if anyone was having problems downloading the KMZ. Here is the link again:
http://70.114.149.18/~mwillis/Hexakopter_3D_Mapping.kmz (~13.2 Mb)
Mark Willis June 9, 2010 at 9:05am

Paul, I'm still trying to figure that out but it is really a function of the resolution of the data you need. The higher the craft is flown, the more area you can cover with each photograph and the faster you can travel between points and still get good overlap with the images. The higher you fly the less resolution you've got in both the DEM and photomosaic.

I'll be flying at a large archaeological site that is 1.1 by .4 km in size later this summer. That should really test the boundaries of the machine and technique. This should give the best evaluation of the process using the hexakopter. I've also got a Hawkeye setup with ArduPilot. Hoping to see how it does also.

Using the hexakopter there really aren't any bottlenecks (other than the learning curve of LPS which is very steep) in the post-flying workflow. The largest bottle neck is the flight time (about 18 minutes) and self-imposed limitations of the Hexakopter (maximum flight radius is 254 m).

If you compare the time (and cost) it would take to collect the same sort of data with LIDAR, from a manned aircraft, or via traditional ground survey, it's very and fast.
T3

Rory Paul June 9, 2010 at 8:44am

Mark

What is your estimate on the largest area that could be mapped using this method and where are the current bottle necks (flight duration, processing time on the back end)?

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