Aerial images stitching

[Jonathan]

Hello, we have a set of aerial images captured by an UAV, and we would like to stitch them together to have an aerial map, we have tried using hugin but the generated stitches tend to be distorted, our images are taken at the same altitude, have an overlap of ~70% and have gps information regarding the photo location (latitude and longitude), among with altitude and camera info, is there a way to make hugin use the position data to align the images so we can have more accurate stitches? please take in mind that we want to be able to do this through the command line in the future.

kind regards

[Terry Duell]

Hello Jonathon,

Your UAV is flying at constant altitude, but is the ground surface planar,
i.e. flat?
You are essentially collecting images to stitch in mosaic mode, in which
case the surface should ideally be planar, but that does depend on the
altitude and the variation in elevation of the surface.
If the variation in elevation is small and altitude is large, stitching in
mosaic mode should give a reasonable result.
Others who frequent this forum have done quite a bit of work in perfecting
methods of stitching shots of large maps which are not exactly flat due to
creases from folds. Some of the experience with that may be applicable,
not sure.
A tutorial on hugin's mosaic mode is here
<http://hugin.sourceforge.net/tutorials/Mosaic-mode/en.shtml> if that is
of any help to you.
An alternate approach is to use a GIS, such as GRASS, which has features
specifically for your work.

Cheers,
--
Regards,
Terry Duell

[bugbear]

Terry Duell wrote:
>
> Your UAV is flying at constant altitude, but is the ground surface planar, i.e. flat?
> You are essentially collecting images to stitch in mosaic mode, in which case the surface should ideally be planar, but that does depend on the altitude and the variation in elevation of the surface.
> If the variation in elevation is small and altitude is large, stitching in mosaic mode should give a reasonable result.

Unless the UAV is maintaining a perfect horizontal position you may need to optimise
all of X,Y,Z,Pitch,yaw,roll.

Doing this in a stable fashion is more difficult than you'd like.

> Others who frequent this forum have done quite a bit of work in perfecting methods of stitching shots of large maps which are not exactly flat due to creases from folds. Some of the experience with that may be applicable, not sure.

Indeed.

BugBear

[Alex Mandel]

As others have pointed out, use of Hugin for this purpose requires quite
a bit of manual labor tweaking settings, etc...

Another OpenSource product to try is OpenDroneMap
https://opendronemap.github.io/OpenDroneMap/

Also see slide 17 of this talk I helped with.
http://www.slideshare.net/MicheleTobias/the-drone-alternative-multispectral-kite-aerial-photography-photo-processing-workflow

Thanks,
Alex