[OpenDroneMap-users] How to troubleshoot orthophoto

[Dennis Baldwin]

Team,

I've opened an issue here and will continue to investigate. Any insight is
much appreciated.

https://github.com/OpenDroneMap/OpenDroneMap/issues/350

Thanks,
Dennis

On Thu, Jul 28, 2016 at 1:24 PM, Dakota Benjamin <
dmb2 at clevelandmetroparks.com> wrote:

> So I don't see in the exif where AGL is but it looks to me like the GPS
> Altitude attribute is AMSL, and that is the line taken from exif to
> determine Z. In fact, the extract_utm command parses from a jhead output to
> extract the line containing the string "GPSAltitude" from the jhead
> output.
>
>
>
> [image: http://sig.cmparks.net/cmp-ms-90x122.png]Dakota Benjamin
> Geospatial Developer
> clevelandmetroparks.com <http://www.clemetparks.com/>
>
> <http://www.clemetparks.com/>
>
> ------------------------------
> *From:* Khyale Nascimento <khyale at hotmail.com>
> *Sent:* Thursday, July 28, 2016 1:29:06 PM
> *To:* Dakota Benjamin; opendronemap-users at lists.osgeo.org
> *Subject:* RE: [OpenDroneMap-users] How to troubleshoot orthophoto
>
> The exif data is attached. I will check the point cloud.
>
> ------------------------------
> From: dmb2 at clevelandmetroparks.com
> To: khyale at hotmail.com; opendronemap-users at lists.osgeo.org
> Subject: Re: [OpenDroneMap-users] How to troubleshoot orthophoto
> Date: Thu, 28 Jul 2016 13:29:28 +0000
>
> Are you both seeing the same warping in the point cloud as well? If so
> then this is an OpenSfM issue.
>
>
> > manipulation of focallength and ccd width
>
>
> From what I know OpenSfM uses ccd_width for initialization of the process
> and so inaccuracies shouldn't mess it up too bad. I don't remember if it is
> the same for focal length as well. Are you doing camera calibration on top
> of this image manipulation?
>
>
> My suggestion would be to open up an issue on GitHub and document your
> process with as many specifics as possible. I will ping the OpenSfM dev to
> see if they have insights into the issue at hand.
>
>
> Khyale, you bring up an interesting point. I'll look into the code and see
> how it extracts altitude information. Can you upload an image with this
> exif or paste the output of exifread/jhead?
>
>
> Thanks all,
>
>
> Dakota
>
>
>
> [image: http://sig.cmparks.net/cmp-ms-90x122.png]Dakota Benjamin
> Geospatial Developer
> clevelandmetroparks.com <http://www.clemetparks.com/>
> <http://www.clemetparks.com/>
>
> ------------------------------
> *From:* OpenDroneMap-users <opendronemap-users-bounces at lists.osgeo.org>
> on behalf of Khyale Nascimento <khyale at hotmail.com>
> *Sent:* Wednesday, July 27, 2016 9:08:19 PM
> *To:* opendronemap-users at lists.osgeo.org
> *Subject:* Re: [OpenDroneMap-users] How to troubleshoot orthophoto
>
> Hi,
>
> I have the same problem reported by Dennis. Large regions in my orthophoto
> may be skewed or distorted. I used the same set of images in pix4dmapper
> and it works well. I used 65 images captured from Inspire 1. The value of
> altitude extracted from exif data may interfere in the reconstruction?
>
> In reconstruction, should I use the Absolute Altitude (AMSL, altitude
> Above Mean Sea Level) or Relative Altitude (AGL, altitude Above Ground
> Level)? The image's exif data gives me both. In Inspire 1, the 'Relative
> Altitude' is calculated from the barometer sensor data. And I note the ODM
> uses the altitude AMSL in the their processes.
>
> Thanks,
> Khyale.
>
> ------------------------------
> From: db at unmannedairlines.com
> Date: Wed, 27 Jul 2016 15:59:49 -0500
> To: s_mailinglist at geraschs.de
> Subject: Re: [OpenDroneMap-users] How to troubleshoot orthophoto
> CC: opendronemap-users at lists.osgeo.org
>
> Simon, thanks for the suggestion.
>
> My GPS EXIF data is all accurate from my testing. I've run it through
> Photoscan multiple times and have tried ODM a few times over the past
> several days. If you want to see the dataset you can find it here:
>
> https://www.dropbox.com/sh/zyuxr73df4ozitu/AABixfPR-nmOHU5yL_1MOmyka?dl=0
>
> This includes the source imagery (95 files) plus the output geotiff from
> Photoscan.
>
> On Wed, Jul 27, 2016 at 3:33 PM, Simon <s_mailinglist at geraschs.de> wrote:
>
> Hi Dennis,
>
> have you used the georeferencing option in one of the two ways possible?
> Could be related to wrong GPS info in the exif tags, or in the GCP-lists
> file...
>
> Regards, Simon
>
> On 07/27/2016 09:55 PM, Dennis Baldwin wrote:
> > Hi,
> >
> > I've been working with some aerial imagery that I shot over the past
> > few months. Basically doing a comparison of ODM output with my
> > Photoscan results. Unfortunately with the latest codebase I've been
> > getting some pretty strange results when generating an orthophoto. You
> > can see what I'm talking about here:
> >
> >
> https://www.dropbox.com/sh/extsb6o6jaoq8t2/AADRvkeINPydFVwKDaheZtzSa?dl=0
> >
> > You can see the intended results from Photoscan (after running through
> > gdal2tiles) here:
> >
> > http://www.unmannedairlines.com/dev/tiger_stadium
> >
> > My question is what is the best way to go about troubleshooting these
> > results? I have all of the log output, but am not sure of the best
> > place to start. This imagery was generated with a Phantom 4 so I did
> > have to do some manipulation of focallength and ccd width just to get
> > ODM to run. Perhaps I botched something there.
> >
> > Any insight of where to start would be much appreciated.
> >
> > Thanks,
> > Dennis
> >
> >
> > _______________________________________________
> > OpenDroneMap-users mailing list
> > OpenDroneMap-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/opendronemap-users
>
> _______________________________________________
> OpenDroneMap-users mailing list
> OpenDroneMap-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/opendronemap-users
>
>
>
> _______________________________________________ OpenDroneMap-users mailing
> list OpenDroneMap-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/opendronemap-users
>
> _______________________________________________
> OpenDroneMap-users mailing list
> OpenDroneMap-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/opendronemap-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/opendronemap-users/attachments/20160731/10bfcc3f/attachment.html>