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Mar 28 2012

Forest Fire Videos Captured with a Hexakopter

Here are links to two videos we collected of the forest fire we flew in early March in New Jersery.  Stephen had posted previously, post here, about our experiences getting the payload to fly on the Hexakopter, a repeat of similar work from last year.

Taking video was an afterthought for the project so we only had an SD4000 on hand for filming.  I think the video quality would have been a lot better if we had the GoPro.  Despite the wiggle and bluriness of the video, it is still possible to see the smoke lines set by the fire managers (see images at left) and there are places in the afternoon video where I think you can even see fire.  Note that these videos were taken pointing about due west, so I believe the shots from later in the day appear darker due to exposure compensation.

Video from about 12:45 - 12:55 local time: http://youtu.be/q3S3V3212bo?hd=1

Video from about 15:45 - 15:55 local time: http://youtu.be/GQHh2LX_ad8?hd=1

Oct 14 2011

Mikrokopter and Computer Vision/Photogrammetry used for Landslide Modeling

Researchers at the Universität Stuttgart, Institute for Geophysics in Stuttgart Germany, have used manually flown Mikrokopters and semi-automated photogrammetric software to generate high resolution photo mosaics and digital terrain models of a landslide area for tracking terrain displacement.  

An article published this spring in the journal Engineering Geology demonstrated the value of using remote controlled aircraft and off-the-shelf digital cameras for high resolution digtial terrain modeling.  The researchers used photogrammetry and computer vision software VMS to make 3D terrain models with aerial images and compared the results to aerial LIDAR and TLS terrain models.  A network of ~200 GPS measured ground control points were used to assist with image registration and model accuracy with good results.

The authors appear to agree with our sentiments that RC based aerial photography and 3D scanning has the benefits of low-cost and repeatability compared to traditional fixed wing or satellite based data collections.

Unlike our research, the authors of this study were interested in only the digital terrain model (DTM) and vegetation was considered noise to be removed for more accurate surface modelling.

Again...just one more reason for me to get cranking on that next paper!

Image source: http://commons.wikimedia.org/wiki/File:Super_sauze_landslide.JPG

Jul 29 2011

Multirotors on the Colbert Report

Check out multirotors on the Colbert Report!!!  The clip starts at about 15 minutes into the program.

The researcher, Missy Cummings Associate Professor from MIT, is developing better human multirotor interfaces to help people steer the units using only a smart phone, which makes me wonder how different it is from the Parrot AR.Drone.

 

http://www.colbertnation.com/full-episodes/wed-july-27-2011-missy-cummings

Seeing this video reminded me of something I noticed when flying the Hexakopters on campus with Tom Allnutt last week, see his post here.  Many people stopped and asked, ‘What is that?’, as usual, while we were out practicing in the Quad at UMBC.  But almost everyone asked if we had put a camera on it, as if that was the obvious thing to do with such a cool device.  I explained to them our research and that we do usually fly with cameras and thought to myself that something is different now then when we were practicing last year.  In September 2010 when people asked us what we were doing they never asked if we were putting cameras on the devices and thought it was an odd thing to do when we told them about our work.  Now it seems that the practice is even expected.  I hope this signals a shift in perception about autonomous vehicles as useful tools for research and for recreational aerial photography and not just greater public awareness about the other uses of such devices.

UPDATE: I've been thinking about this post and in all fairness, the researcher is discussing the use of multirotors by the armed forces.  I posted for the sake of noting the signifcance of the devices in pop-culture.

Jul 15 2011

First Altitude Controlled Hexakopter Flight!!!

 

This past week I've been working on flashing the new firmware to fly altitude controlled waypoints. As it turns out there was no need for the newest hardware to use the latest firmware (FC 2.1ME, BL 2.0 required). After working out some compatibility issues with the old version of MKtools, I finally was able to connect to the Hexakopter. Today we were able to do a flight test, check out the video for yourself (best in full screen hd).

Next week I plan to flash the new firmware on to the other 2 remaining Hexakopters.

 

                                                                                        Why are you reading this watch the video!

Oct 19 2010

Flight Telemetry Data and Monitoring the Flight

We recently learned about the robust telemetry data that the Flight Control board creates when a MicroSD card is plugged into the onboard slot.  Since then we have always flown with the card in to capture the telemetry data and it is proving to be an invaluable part of the post-flight assessment process.

The next steps will require a *simple* GIS workflow to evaluate whether the actually flown path sufficiently matches the pre-planned path to provide the necessary image sidelap and endlap for 3D reconstruction.  

We have already seen first hand how deviations in the fight plan tracks result in gaps in the vision reconstruction and also how mis-aligned platform orientation results in gaps as well.  At a flight at SERC the platform and camera where oriented 90 degrees from the path of travel, resulting in no sidelap between parallel tracks, link to Photosynth.  At a recent flight in New Jersey the wind blew the little guy around a lot and even though the camera orientation was spot on, the width between some parallel tracks exceeded our flight plan for achieving side lap, again resulting in large scan gaps, link to Photosynth.

So what does this mean?  It is necessary not only to have spot-on preparation of camera orientation and flight planning prior to flight, but it will be necessary to run diagnostics in the field to evaluate whether the route flown was sufficient for 3D reconstruction.  I wrote a simple python script to translate the Mikrokopter GPX telemetry data into a text file for use in a spreadsheet or GIS program.  By doing this we can look at characteristics of the flight system through time (e.g., battery voltage vs. flight time) or space (e.g., Navi-Ctl status messages at each GPS point along the flight path).  The Python script that translates Mikrokopter GPX telemetry data to a text file is located on our Coding Corner page.

Sep 21 2010

You've got to let the little guy's leash out!

This afternoon I worked with Nisarg to better understand how to setup a path for collecting aerial photos with the Hexakopter.  We quickly found that doing so would not be difficult and that adding our own custom waypoint list to the Mikrotool was straightforward.  However, during the fligh test we learned about an important setting to be aware of in the Navi-Ctl that really limited our test today.  By changing the settings as described below, we should be out flying over the entire Knoll in no time!  I think Nisarg is going to post later about the Mikrotool Map software that he was working with that provides an easy system for getting a Google Earth image into the Mikrotool OSD.

 

In testing our waypoint options, Nisarg was able to create an output text file (a .wpl file) of the Mikrotool OSD waypoints.  The file looks like this:

[General]
FileVersion=1
NumberOfWaypoints=10
[Waypoint0]
Latitude=39.253988
Longitude=-76.71177
Radius=10
DelayTime=1
[Waypoint1]
Latitude=39.251826
Longitude=-76.711718
Radius=10
DelayTime=1
[Waypoint2]
...
...

I looked at that and thought, “Well I can make that!” and set about generating a waypoint file over a route we wanted to fly for the Knoll site on campus in ArcGIS.  We had been discussing flight strategies and how to achieve image overlap and I showed Nisarg and Garrett a little bit of the kind of map making and simple spatial functions that can be done in ArcGIS: Garrett seemed more impressed than Nisarg.  I have been consulting Elements of Photogrammetry a lot recently for flight planning and also some simple calculations I made of the amount of overlap and area observed by a camera at a given height above the ground surface. I will be posting more about that later.

Anyway.  We came up with the a simple parallel grid track for the Hexakopter to navigate over the Knoll with 50m spacing between tracks.  I estimated that at about 70m altitude from the ground (@ Home) I would achieve the desired overlap even over the Knoll and trees. We went outside with the gear, climbed up to the top of the parking garage and went for it.  We also had a Garmin Edge GPS attached to the top of the dome to provide a track of where the little guy was going: not sure if the MKGPS can record tracks.  From the beginning it seemed like something was wrong.  It was kind of flying in the correct pattern, but it did not seem like it was going far enough across the forest.  We brought it back down and took a look at the GPS track.

As you can see in this somewhat messy image, the little guy did not go exactly where we wanted him to. 

A brief legend:

  • - Blue lines are the intended route
  • - Green dots are the intended waypoints given to the Mikrokopter
  • - House symbol is flight home
  • - Large yellow arc is a 250m buffer around the quad, more on this below
  • - Small yellow circle is a 100m buffer around fight home

So what happened?  The Hexakopter tried its best to fly those waypoints, but kept hitting an invisible wall and was forced to come back.  The units come preset with a GPS maximum range of 100m.  So our guy was flying his path, hit that 100m mark and was deflected along his route without hitting all the points.  Through a bit of research we came across the issue on the forums, http://forum.mikrokopter.de/topic-13563.html, and the solution on the Wiki (linked from the forums): http://www.mikrokopter.de/ucwiki/MK-Parameter/Navi-Ctrl_2 .

The units still will not fly beyond 250m with GPS with the current setup.  We thought that this was the default setting and hence set up our route to fly at max 250m across the Knoll from an intended Home in the quad, that is why the larger yellow arc is not centered. 

From here we are going to update the Navi-Ctl setting to allow us to fly to the max 250m from home and I am going to put together a small script in Python to turn an ArcGIS point file table into the waypoint format needed for the Mikrotool…but maybe not by Friday!

refs: Wolf, P., DeWitt, B., 2000. Elements of Photogrammetry with Applications in GIS 3rd Edition, McGraw Hill.