Hi All,
I've been requested to produce geo-referenced, single framed images take from a UAV. I'm successfully able to create ortho mosaics but am unsure how to automatically generate individual geo-referenced frames. Any suggestions for the most efficient way to do this for a series of photos. The attached images demonstrate how the individual frames would appear. Thank you!
Replies
Interesting question. Not sure what purpose it serves, but let's try to answer this.One thing that's important to understand is that your pictures hardly ever make nice rectangles on the earth due to issues like barrel distortion, oblique imagery and of course differences in terrain elevation. So if you want to fathfully represent the parts of an image, you need to project your source images against a DEM of some kind as well, or you may overproject things and then your pictures look very skewed.
1. You can always use qgis to load your final ortho and each separate image to georeference each image with the georeferencer plugin and export as a geotiff file. For many files, this is certainly a bore.
Unfortunately doing this automated is quite complicated, most tools work forward towards an orthomosaic, not backwards.
So I can't give you a direct answer, but here are some thoughts on how you can approach the problem:
1. if the original source images are allowed to be changed for the purposes of rectification, then you can look into hugin in an effort to rectify your images first, then project them: http://wiki.openstreetmap.org/wiki/User:Balrog/Aerial_Imagery/Recti...
2. Another interesting try is to use the export of camera calibration and position information that many photogrammetric tools can export. This gives you very accurate attitude and position info for each camera, which you can use to reproject your source images against your DEM. Unfortunately I don't know which tool would be able to do this *and* provide georeferenced information in the photo.
3. The final approach I can propose is to find tools that allow you to co-register your source file against the final orthomosaic. Here it simply looks for pixel data that matches. If your orthomosaic is georeferenced, then it may be possible with some tool to transfer the coordinates of this "projection" or "match" into your source image.
Hi Gerard,
Thank you for taking the time to leave such detailed feedback regarding this inquiry! Since making this post I have confirmed that this task is possible when using Agisoft Photoscan, pix4d and MosaicMill. I'm sure other software can produce similar results too. Thanks again for your response!