Recommended camera angle when collecting photos from drone in grid flight pattern

RE: Recommended camera angle when collecting photos from drone in grid flight pattern

Oto — Thu, 26 Jan 2023 11:02:39 GMT

Better some answer as no answer as often questions are left without any answer.

[quote userid="1299809" url="~/products/3d_imaging_and_point_cloud_software/f/contextcapture-descartes-pointools-forum/240880/recommended-camera-angle-when-collecting-photos-from-drone-in-grid-flight-pattern/750700"]A 15 minutes mission with our drone suddenly rise to 55-60 minutes going from only nadir in lawn mower pattern to oblique in grid pattern.[/quote]

That unfortunately is expected. You could lower overlap but risk that some photos may be lost but in your case it may not be problem if possible to fly again as normally it is not easy possible to go back to the site. Your drone is not well suited for covering larger areas you would need to use fixed wing drone or with high resolution camera so can fly higher and cover larger area.

When flying at 100m may work with less overlap as trees doesn't mess so much with aeortriangulation at least if not windy. When flying lower like 50m and missions take too long time the moving shadows also start to cause issue with AT.

RE: Recommended camera angle when collecting photos from drone in grid flight pattern

Anders Theodorsson — Wed, 25 Jan 2023 20:05:59 GMT

Thank you Oto, quick response - as always! I'll stick with the grid pattern, it will be too time consuming running circles over the whole town. Maybe try that on some important objects where higher resolution might be wanted.

Also I'll try creating the orthophoto from the 3D-model as suggested and compare with one made from nadir photos or a mix of oblique and nadir. I might even run a set of photos in Agisoft to compare the orthophotos.

Do you - or anyone else have a recommendation regarding overlap between photos in the grid? I think a final overlap of 70% in one direction is quite much. It reults in the need of 85% overlap when running back and forth! A 15 minutes mission with our drone suddenly rise to 55-60 minutes going from only nadir in lawn mower pattern to oblique in grid pattern.

RE: Recommended camera angle when collecting photos from drone in grid flight pattern

Oto — Wed, 25 Jan 2023 19:05:50 GMT

Double grid with camera angle between 60-70 gives the best result and no need for Nadir at all. You can generate orthophoto from 3D process then but orthophotos from 2.5D process from Nadir only could look slightly better(trees, building corners) also 2.5D is easier to retouch. Unfortunately Contextcapture doesn't produce best looking orthophotos even in 2.5D at least for me.

Also Bentley now recommends overlapping circles missions(some planning apps has such) as it gives better calibration but I would recommend stick with good pre-calibration anyway and overlapping circles may not be easiest to get consistent coverage.