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Author Topic: Axis Orientation  (Read 7032 times)

ChrisF

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Axis Orientation
« on: February 14, 2014, 02:29:04 AM »
Hi,

I suspect my problem may exist between the chair and the keyboard, but any guidance would be appreciated.

I am trying to create a orthomosaic and DEM to measure a volume. I have taken 200 or so photos with D800 from a multi-rotor at an average heigh of 60m above ground level, I am getting good overlap when I run the report function.

I have then used the GPX file from the UAV flight log, and the time stamps from the photos to identify the camera locations.

When I plot the camera coordinates in a graph excel they come out showing the flight pattern as expected, however when I load the txt file into Photoscan the points come out in a straight line.

Subsequently when I align the photos in PS the axis are not correctly aligned, the z axis appears to point in a random direction and x and y are not aligned to the horizontal ground plane. From reading the tutorials Z should be vertical automatically?

I think this is also effecting the scale of the model, as when I try to measure a volume the numbers produced are very small in comparison to what I would expect.

I don't have additional GCP for this model.

Any pointers would be appreciated.

Also, I am running PS on a new MacPro with 12cores 64GB of RAM and D700 graphics cards, so if someone can point me in the direction of a "standard" data set and settings, I'm happy to run a benchmark test and post the results.

Thanks

Chris

chadfx

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Re: Axis Orientation
« Reply #1 on: February 14, 2014, 02:41:02 AM »
Hi Chris, sorry I have no advice for your issue. (but hopefully some of the aerial experts here can help)

For the benchmarking, there is a thread here with a setup based on one of the PS sample sets:

http://www.agisoft.ru/forum/index.php?topic=651.msg3312#msg3312

Very curious to see if PS really hammers on those dual D700's. It doesn't seem like a lot of software really takes full advantage of them unless specifically coded to do so.

Cheers, -Chad

Alexey Pasumansky

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Re: Axis Orientation
« Reply #2 on: February 14, 2014, 10:15:12 AM »
Hello Chris,

Looks like the coordinate system has not been set to WGS84 in the Ground Control settings dialog. Could you please check that?
Best regards,
Alexey Pasumansky,
Agisoft LLC

ChrisF

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Re: Axis Orientation
« Reply #3 on: February 14, 2014, 10:38:20 AM »
Thanks Alexey,

I had set the coordinate system to GDA94/MGA55 which is the local coordinate system.

So when I change the coordinate system, the WGS84 it all lines up and the volume calculation works as expected.

When is it appropriate to select the local coordinate system, only for final output of DEM and Orthophoto?

Thanks

Chris

Alexey Pasumansky

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Re: Axis Orientation
« Reply #4 on: February 14, 2014, 11:41:51 AM »
Hello Chris,

In the Ground Control pane settings you need to specify the coordinate system corresponding to checked on camera/marker coordinates in the pane.

You can convert coordinates either using Convert button (if it is more convenient to operate local coordinates), or switch to desired system already in Export DEM/Orthophoto dialog.
Best regards,
Alexey Pasumansky,
Agisoft LLC