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Author Topic: Model upside down and tilted  (Read 5524 times)

jailblazers

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Model upside down and tilted
« on: July 28, 2014, 08:08:50 PM »
I'm using aerial photos from a mini UAV in Photoscan Pro to make a surface model of a group of trees but the dense cloud keeps coming out upside down as well as tilted (rotated).

The flight controller on the mini UAV doesn't allow me to download camera position data, but I did lay out 10 GCP targets around my stand of trees that I took relatively accurate (~1m horiz/vert) GPS points with.  Have followed the Orthophoto and DEM Generation (with GCPs) tutorial quite closely to  align photos without camera positions, place markers on my GCPs, and load GCP coordinates, set coordinate system, etc...

I've checked several times and I'm quite certain that I haven't confused my easting/northing coordinates when I import my ground control coordinates text file.  I have also made sure that the red-colored side of my bounding box is located underneath my model.

Because of the height of the trees in the aerial imagery, in a few photos some of my GCPs on the ground are obscured by the trees. In these images, the marker in the Ground Control workpane for a certain GCP I'm working on will be on top of the trees. I'm starting to think that this might be contributing to why my model is tilted, but having a hard time understanding why it appears to be mostly upside down.

Should I be disabling the GCPs that have been obscured in some of the images, or disabling the cameras that have hidden GCPs in them?  Is there a way to delete a single marker point from a single camera when it's hidden by the trees?

Thanks in advance!

Alexey Pasumansky

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Re: Model upside down and tilted
« Reply #1 on: July 28, 2014, 08:13:45 PM »
Hello jailblazers,

For the GCPs that are not visible on the photos you shouldn't specify the projections, just leave gray flags and they would not be taken into consideration for the marker position estimation. To remove such projections just right click on it in the Photo view mode and choose Remove Marker option from the context menu.

If the problem is still there, please send the project file with aligned cameras and placed markers to support@agisoft.ru.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Ron

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Re: Model upside down and tilted
« Reply #2 on: July 31, 2014, 03:19:51 AM »
Hi Jailbazers,

I get the same problem when I use camera positions without co-ordinates. My method is to do as Alexey suggests and in addition uncheck the cameras (Markers checked), then align photos. This gives camera positions based on the ground control co-ordinates. This works fine for small projects (<100 images). Haven't tried this on large projects.

Cheers,

Ron