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Author Topic: Photos keep aligning on 2 (or more) intersecting planes  (Read 1837 times)

bevenro

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Photos keep aligning on 2 (or more) intersecting planes
« on: May 30, 2016, 10:21:43 PM »
HI forum,

Another UAV-survey related question. I've got this UAV survey with about 3,000 images, which I'm now doing in chunks (to troubleshoot, more than anything else).  Each chunk represents a somewhat-systematically acquired part of my survey area, and contains 100-200 photos.  Some of the chunks align very well (not perfectly, but 90-95% alignment), and I've been getting some nice dense point clouds/orthophotos.

In other chunks, I may get 80-90% ailgnment, but the point cloud is generating points along intersecting planes (or in some cases parallel planes).  To troubleshoot, I"ve selected some of these points, run a Filter Photos by Points to isolate the offending images and remove them, then I try to realign those images.  But I get the same thing.

Now I'm going to try adding some markers prior to the alignment stage, and place them on 4-6 photos (with GCP coordinates).

So my questions:

1.) what tends to cause this intersecting plane issue?
2.) can setting a few markers in advance help this?
3.) does it matter if I used generic, Ground Control, or disabled point selection?  (I"m thinking that when I use the Ground Control pair-preselection it is using the UAV GPS coordinates which aren't all that accurate--maybe that's causing a conflict somewhere?

Any thoughts woudl be appreciated!

bevenro

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Re: Photos keep aligning on 2 (or more) intersecting planes
« Reply #1 on: May 30, 2016, 10:25:03 PM »
update: may have solved my own problem--I set 3 markers (with DGPS coordinates), then shifted from Ground Control to Generic.  Seems to have fixed the intersecting plane problem  8)