image alignment of forested areas

[dowallin]

I realize that the alignment of images from forested areas is challenging. I'm wondering if anyone has any tips for getting more images to align. Specifically, in the "Align Photos" dialog, I'm wondering if using a lower accuracy or changing the Key point or tie point limits would help (and what settings for these options might help).

Thanks!
David
 

[PROBERT1968]

Yes it is, but what kind of imagery do you have ? I work with old historical aerial imagery and they don't have the coordinates. They were scanned from a contractor and they were in black and white. They are diffcult to find any features but you just have to do the best to find them.

I use Google Earth Pro to find the features there and input their coordinates into PhotoScan.


Let me know if you have any questions. I work with US Forest Service in Colorado, United States.

[dowallin]

Robert,
I am working with imagery collected using small quadcopters at altitudes of 300-400'. I've used the 3DR Solo quite a bit and just purchased a DJI M210 The images are usually geotagged (though some images lack geotag due to GPS glitches). These geotags are NOT precision geotags; probably +- 5 to 10 m. I use a variety of cameras; Parrot Sequoia, older Canon S100 and a new DJI X4.

I am a university researcher in Washington state.

Regards
David

[dowallin]

Robert,
And I neglected to mention that I generally fly with 75-80% sidelap and frontlap. Trees in my area generally 100-150' tall. I realize that a ground overlap of 75-80% yields a smaller overlap at the top of the trees.

D

[wizprod]

You probably won't have enough overlap with those high trees. Try and increase the overlap. Dronedeploy has some good tools for calculating this.

[PROBERT1968]

Yeah wizprod was right about that it would not overlap right... it needs to be to be in around 40-60 percent to be overlap or otherwise you will see gaps.. if you have a smaller Stereoplotter you would see two images overlap each other and you would see some features "raised"  It is the same thing with PhotoScan ...