Aerial mapping: first results
Hi all,
I want to share with you the first results obtained with my Bixler-UAV. I had never flown a RC plane before but must say that this little hobby quite gets into your skin once you get familiar with all the basics. So I started with an Bixler ARF kit and made must adaptations according to this guy:
Make sure to read all about CG before your first test-flight, or you’ll be climbing trees to get back your precious toy. Needless to say that the learning curve was steep..
Today was a calm day (7km/u wind), perfect to make the first flights with a camera.This is the setup:
Airframe: Bixler - Still my first one. Unbelievable tough and when you brake something, there is always the CA glue to the rescue. I moved the ESC outside so it cools down easier and you can connect the battery without moving the mounting platform with all the electronics. I also cut out a hole below the nose of the plane for the camera to fit. Foam along all sides of the camera should reduce the vibrations
Autopilot: APM1 with GPS, airspeed sensor, magnetometer and 2.4GHZ Xbee. Except the X-bee, everything is mounted on the Bixler electronc chassis. Works like a charm, just as described by all the great people here at the site. I used the bixler.param file posted by Chris and played around with some of the PID settings. Now with the camera integrated I have to do some more twitching with the extra weight.
Camera: Canon IXUS 220HS with CHDK interval meter. Just like these guys from conservationdrones.org/. Fits perfect in the nose
Morning flight
Camera setup: Focal length: infinity; ISO:auto; Shutter time: 1/500
Average Altitude: 100m (still to verify)
Average Ground Speed: 12m/s (still to verify)
Number of images taken: 260 (did the track twice). I had many blurred images and had to remove 140 images before stitching. Shutter time was set to fast.
Evening flight:
Camera setup: Focal length: infinity; ISO:auto; Shutter time: 1/1000
Average Height: 100m (to verify!)
Average Ground Speed: 10m/s (to verify!)
Number of images taken:194. I had only 6 blurred images, but overall scene was too dark. Next time I will fly with better illumination conditions.
The stitching was done with Microsoft ICE, I will also be looking into software which include the GPS/IMU information into a real map. Comments, suggestions,.. always welcome!
cheers
Dries
Replies to This Discussion
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Permalink Reply by Jeff Taylor on -
Nice job Dries, your map looks great!
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Permalink Reply by Airfoto.se on -
Well done, great result. I ´m doing mapping to buth with the Zephyr II
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Permalink Reply by Dries Raymaekers on -
Thanks!
@JP, the ICE software took 20min for the stitching and 30min extra to write the full resolution jpg file. You see that towards the edges the stitching was not quite successful. Would your processing chain (dronemapper) do a better job with the XY/RPY information provided?
@Braker, the MicMac program appears not to work on my home pc. Will give it a try on linux! Do you have good experience with this software?
I calculated some statistics about the second flight based on the output kml file. This is the waypoint pattern, together with the flight track. You can already guess from where the wind came..
Is this kind of pattern normal for my kind of plane (Bixler) or can this be improved with tuning PID further? Next pattern I will try to fly parallel to the wind!
Some more statistic about the flight (extracted from the kml):
Height: average 116m with min/max values of 111m and 121m. Height above surface was set to 100, home location height was “set this time” to 15m. “This time”, as it has the habit to change from flight to flight (range from 10 to 60m). I would think this is height above the WGS-84 datum, but this would be more in the range of 60m. Anybody a clue on why this is?
Speed: I projected the latlong to UTM and calculated the speed over a 5 seconds interval. Average speed is 12m/s with min/max values of 30m/s and 6m/s. From this you can see the difference between (ground) speed with and against the wind. I would think this would be handled better with the airspeed sensor I installed, but apparently not... or not installed properly.
Roll/pitch/Yaw: as you can see a pretty bumpy ride. In the straight sections of the path roll varies from -10 to 10deg. Pitch is more constant, around 4 degrees down. Yaw .. is the yaw .. rudder is not very active in the bixler I am afraid.
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