Hi!
I made an inspeccion of the underneath part of a bridge, and wasn't able to georeference the images (GPS interference with the metallic parts).
Anyway, I was triying to make a ortophoto and can't do it because of huge distorsion of the images. The drone was flying close to the bridge (3 meters) and the overlap of the images is enough (between 40-60%). The problem is not the overlapping, seems to be very different orientation and distorsion for being so close to the infraestructure.
Has anyone do something similar? How can I solve it?
Thanks everyone in advance!!
Juan
Replies
Hi Juan,
This is normal, when you have high objects they generate a certain distortion in the image due to the perspective. Different softwares generate different results because of differences in the algorithm. In pix4d however you can choose which photo you want to use for that part of the orthomosaic, which will reduce the effect, but you may then have slightly inaccuracies where the edges are located (which will be somewhat inaccurate anyway).
I think for such flights a certain distance away from the highest point is a better way of reducing that impact. So if you have a bridge 20m high, you should go for at least 40m flight level, ideally somewhat higher. That does impact your GSD of course, but you should evaluate what's more important.
First of all, thanks for your answer.
The main problem is that the bridge is mostly 5-6 meters high, so we flew the drone 3 m. high to have a proper view of the underneath part of it and not fliying too close to it.
So, when we started to make the orthophoto we found the problem...and the logs of the drone doesn't help because the GPS didn't worked under the bridge.
Im finding that it's mostly impossible to fix it so we should repeat the work ( :( )
Thank you!!