Looking for photogrammetry advice

Posted by Jay Johnson on June 21, 2013 at 1:14pm
I am interested in using a UAV to generate orthophotos.  I'm a GIS/mapping guy and amateur robot-builder.  I'm trying to figure out a good entry point (hardware, software) into the world of UAV mapping. 
 
I'm not a afraid of a little R&D, but I'd really like to find a solution that I can get up and running reliably and I don't see any reason to reinvent the wheel.
I'm considering the Ardupilot Hexa-C.  From what I can tell there are free software solutions, notably including Mission Planner and Palentier, to collect and process the raw photos into a seamless orthophoto.  (Basically an orthophoto has been geometrically corrected to remove inherent scale distortions, so that measured ground distances within the photo are consistent.)
 
Anyone out there doing this that can offer adivce for someone just getting into it?  Mainly, I don't want to spend $1000 and then 1 month later realize I should have gone a different way...
 
Any opinions based on actual experience would be greatly appreciated!
Thanks,
Jay Johnson
 

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Replies

  • Jay Johnson June 22, 2013 at 10:33am

    Excellent points all - I'm really encouraged to see quality responses to what was, admittedly, a rather general question.  Sign of a very healthy user community!

     

    I definitely hear the comments regarding optimization of the platform via round carbon fiber tubes, etc. to extend flight time, but my preferred development path is going to be to buy something that at least works off the shelf and then pursue customization once I've earned my wings with that. 

     

    Thanks all -- I'll be posting as I make progess.

  • Developer
    Bill Bonney June 21, 2013 at 5:35pm
    I think what you need to consider is area covered. Copter carry a camera have fairly short flight times in the order of 10mins. A plane you can get 40+ mins. There is also the tech pod airframe that can achieve over 2hrs.

    A plane is cheaper. A bixler RTF is $50. Then add APM/battery/RC control. You should be good for $400 depending on choices.
  • MR60
    Forrest Frantz June 21, 2013 at 5:32pm

    Choose your ship carefully.

    • When flying a good camera, you want to protect it.  Hex is OK, but Octa is best.  Lose a motor and the octa will still land even towing a camera.
    • When taking photos, stability is key.  Hexa is noticeably better than a quad.  You might research the difference between an octa and hexa.
    • Ending up with the right lifting amps per motor for the size copter you will need is critical for efficiency.  An octa will deliver the sweet spot.
    • For photographing areas, flight time becomes important.  That means weight is critical.  Most off-the-shelf ships aren't that efficient.  For example, my octa is 1 pound lighter than the mikrokopter octa.  That translates into 30% more flight time.
    • Your camera will be pointing straight down, so you don't need an octa V, H, or other odd shape.  Stay with a regular octa.
    • The most difficult part of the ship is tuning the PIDs.  There are PIDs for acro flight, then stable flight, then GPS flight, then altitude flight ... Learn that well and spend time getting that right.  Even an off-the-shelf copter will need tuning when you add a camera and change it's CG and mass.
    • Custom building a copter is the easy part if you take advantage of this forum.  Tuning and what you do with it is the hard part.  If you are interested in building a high performance octa, I'll direct you to where you can find info on this and support your efforts.
    • Custom building a copter won't save money.  A high performance custom octa will still cost about $800 to $900 excluding the batteries, 8-channel radio, and camera. 
  • Dennis Collins June 21, 2013 at 4:19pm
    Hi Jay.

    I've done a bit of mapping, although not via the standard Esri channels. Bought a hexB a few monthe ago with the idea to fool with some mapping. Not having been in the RC hobby before, it was a learning curve. My work has been in GPS navigation, and my goals are to put that and mapping together.

    I'd like to talk to you about mapping and copters, if you would ping me at email dcollins at fourpeaksnavigation dot com.

    Take a look at the web site at fourpeaksnavigation.com. I've fooled around with digitizing old maps. I've also begun work on some custom mapping auto-geo-referencing software, although I have no doubt that someone in the profession full time can put their hands on better stuff than I could write.

    The last few years I have flown NDVI missions over cotton fields in Arizona and Texas in a full sized airplane. The mapping goal is to do that with copters, but there are some things to solve, both on the copter side, and the mapping side of that.
    Four Peaks Navigation
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