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Re: [Paparazzi-devel] platform for agricultural multispectral imaging?


From: Troy Benjegerdes
Subject: Re: [Paparazzi-devel] platform for agricultural multispectral imaging?
Date: Fri, 3 Aug 2012 10:48:19 -0500
User-agent: Mutt/1.5.20 (2009-06-14)

I was starting with video because then there's a continuous recording
and hopefully more information to stitch things together. The 'not
invented yet' is some software that takes a video from an overflight
and then converts it into a super-resolution image, using some sort
of post-processing like what is described here:

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1203208&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F79%2F27099%2F01203208.pdf%3Farnumber%3D1203208


I think the timestamp problem would get a lot better with 15fps video.
What I think is needed to really solve that is some embedded linux
platform that's got a CCD directly connected, like this chipset:

http://www.grain-media.com/html/8128_26_25.htm

(which is what is in the Alfa IP camera I mentioned below)

On Fri, Aug 03, 2012 at 05:10:57PM +1000, Chris Gough wrote:
> Troy,
> 
> In the simplest case, "multi spectral hacking" typically involves 2
> (cheap) point and shoot cameras, not a video camera. One is modified
> to physically remove the NIR filter (and possibly insert some dark red
> glass).
> The images from both cameras are post-processed and stitched together
> on a workstation after the flight, to create one big mosaic.
> 
> Videos are more complicated, probably not what you need to find weeds
> or allocate water / fertiliser. Fixed wings take more photos per
> dollar. I'm starting a project arround christmas to surveying invasive
> species in native bushland, I'll probably be using a ~2kg hexacopter.
> ARDrones are pretty small for carying any external patload.
> 
> Open question: How to get good time synchronisation between images
> (payload linux computer / USB camera) and telemetry (AHRS, fed to
> payload linux computer over UART/FTDI)? I assume the telemetry
> timestamps are accurate, and that the linux computer is doing an OK
> job of keeping time. The problem is that the filesystem timestamps by
> on images to have variable delays (~1s), possibly due to scheduling,
> congestion and I/O buffering. We figure it's adding ~30m error to our
> search and rescue application, which is a significant portion of our
> total error budget.
> 
> We don't have enough processing power to try a computer vision /
> photoprogrametric refinement (It's a realtime application,
> post-processing isn't an option). We have already given the camera
> driver a very high priority on the OS schedule. Are there any other
> "tricks of the trade"?
> 
> Is this something custom camera firmware could help with? I thought it
> might be possible to get the camera to log accurate timestamps
> (perhaps using an external interrupt from PPS on the GPS?). We don't
> have open firmware for our current camera, but maybe with a different
> camera (running e.g. CHDK) this would be possible?
> 
> Chris Gough
> 
> On Fri, Aug 3, 2012 at 2:39 PM, Troy Benjegerdes <address@hidden> wrote:
> > Too many choices ;)
> >
> > What I really liked about the ARdrone was the hardware integration, and that
> > there's a linux kernel running on it.
> >
> > I saw a demo of the Quadshot (thequadshot.com), and I'm quite impressed, and
> > thinking the best way to go might be to strap one of these to the bottom:
> >
> > http://www.alfa.com.tw/in/front/bin/ptdetail.phtml?Part=AIPC120M&Category=106193
> >
> > ... but then I don't quite have a clue where I'd start to to the 
> > multispectral
> > hacking. At this point I think I just want to fly the camera and record
> > 1280x1024 video and then see if it's usefull for determining if I need to
> > actually walk out and pull weeds.
> >
> > On Fri, Aug 03, 2012 at 10:11:12AM +1000, Chris Gough wrote:
> >> Hi Troy
> >>
> >> check this out:
> >>
> >> http://mechatronics.ece.usu.edu/yqchen/paper/08/08C30_igarss_4051FinalPaper.pdf
> >>
> >> Some things have moved on a bit since then, but the "hackeds cam
> >> packed a foam wing" approach is probably a good place to start.
> >>
> >> Chris Gough
> >>
> >> On Fri, Aug 3, 2012 at 2:36 AM, Troy Benjegerdes <address@hidden> wrote:
> >> > I'd like to find out what sort of configurations (airframes, camers, etc)
> >> > other paparazzi users have used for multispectral imaging. I've got a 
> >> > farm
> >> > and for what it would cost me to get a single satellite image, I could 
> >> > put
> >> > together quite a nice RC/uav setup with a camera.
> >> >
> >> > I've played with an ARdrone1 a little bit, but the ultrasonic altitude
> >> > sensor gets kinda confused by 5 foot tall corn, and the built-in camera
> >> > resolution is pretty low.
> >> >
> >> > I might be interested in hacking an ARdrone2.0, and pointing the HD 
> >> > camera
> >> > toward the ground, but only if I can get Paparrazi running on it instead 
> >> > of
> >> > the stock firmware.
> >> >
> >> > Any other thoughts, or comments from someone who's done this?
> >> >
> >> >
> >> > --
> >> > ----------------------------------------------------------------------------
> >> > Troy Benjegerdes                 'da hozer'                address@hidden
> >> > 7 elements Farm                                         TerraCarbo 
> >> > biofuels
> >> >
> >> > An Engineer is a man who can do for a dime what any fool can do for a 
> >> > dollar.
> >> > -anonymous
> >> >
> >> > If you're going through hell, keep going. ~ Winston Churchill
> >> >
> >> > The challenge in changing the world is not in having great ideas, it's in
> >> > having stupid simple ideas, as those are the ones that cause change.
> >> >
> >> >
> >> > _______________________________________________
> >> > Paparazzi-devel mailing list
> >> > address@hidden
> >> > https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> >>
> >>
> >>
> >> --
> >> .
> >>
> >> _______________________________________________
> >> Paparazzi-devel mailing list
> >> address@hidden
> >> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> >
> > --
> > ----------------------------------------------------------------------------
> > Troy Benjegerdes                 'da hozer'                address@hidden
> > 7 elements Farm                                         TerraCarbo biofuels
> >
> > An Engineer is a man who can do for a dime what any fool can do for a 
> > dollar.
> > -anonymous
> >
> > If you're going through hell, keep going. ~ Winston Churchill
> >
> > The challenge in changing the world is not in having great ideas, it's in
> > having stupid simple ideas, as those are the ones that cause change.
> >
> >
> > _______________________________________________
> > Paparazzi-devel mailing list
> > address@hidden
> > https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> 
> 
> 
> -- 
> .
> 
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel

-- 
----------------------------------------------------------------------------
Troy Benjegerdes                 'da hozer'                address@hidden  
7 elements Farm                                         TerraCarbo biofuels

An Engineer is a man who can do for a dime what any fool can do for a dollar.
-anonymous

If you're going through hell, keep going. ~ Winston Churchill

The challenge in changing the world is not in having great ideas, it's in
having stupid simple ideas, as those are the ones that cause change.




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