Tilted model

I’ve encountered a recurring problem on some of my projects - the reconstruction is generally fine and flat without significant bowling (camera is calibrated) but the whole model plane gets tilted somewhere between 10 to 40 degrees relative to the horizon. This results in a significantly skewed and distorted othophoto. What I’ve found is that the tilt is constant within a single flight but when creating maps from two or more flight photos the reconstruction may create several planes (the whole model then resembles an open book). This way part of the map may be perfectly fine while another will get misaligned and skewed. I fly DJI Mavic Air - it’s just a hobby for me so nothing professional. Here are a few pictures from my latest project combined of two flights. There seem to be some bowling present - or maybe not - there’s an abandoned quarry in the middle and each of two flights is tilted differently so it’s hard to say for sure. I’ve used 10 GCPs - 9 around the edges and 1 in the middle. The settings were “Buildings” with DTM and DSM enabled.


Having the same issue here, everytime I try to use pictures from more than one flight the resulted model gets tilted, Here are the results, I inserted a height measurement for comparision.

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Do you have Ground Control Points?

How far apart are the two collections?

Have you checked DOP values for your GPS before each collect? Things can and will shift (sometimes wildly, especially in height axis) over time with non-corrected GPS.


No GCP, first flight was in 22/09 and the second was yesterday (27/09) 5 days apart.
I’m very new to WODM so I don’t even understood your third question, and I wouldn’t know how to correct it.

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Your flight recording should likely have the DOP recorded somewhere.

You could also use something like Trimble Planning Online to get an idea of what the DOP and GPS accuracy should have been like in that site at those times.

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where can i find these flight logs? can i use them to perform PPK operations? I also use a Mavic Air

Flight logs should be in your ground control station. PPK depends on if your sUAS outputs the right Rinex messages in the gps telemetry log.

I use a DJI Mini 2, and I’m all lost with these infos, have no idea what they are, and where to find, could you show me a forum topic, or a website for me to understand this better?

Trimble GNSS Planning

So you would use this website to find where you were surveying at the exact date/time you were there, and it will show you what the Satellite constellations looked like and give you estimates for the DOP (Dilution Of Precision) and other metrics. This will give you an idea of how reliable/correct your GPS measurements were at that site at that time. It does not take into account solar radiation events or other site-local issues, but it can help.

(For context, I relied upon the desktop version of this app to help me plan times to collect data when I was doing Agricultural Field Survey as some of the places I was going had very small windows where GPS-only satellite coverage was any good.)

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