To Fisheye or not to Fisheye

Hi All;

Apols if this has been asked before. I couldn’t find an answer.

Is it better to use the fisheye setting on a gopro 8 with the resultant 6 MB file or narrow with the 2.3 MB file?

Thanks in advance.

I’m not sure that the question has been asked, and if that has been asked, it hasn’t been for a long time.

My position on sensors is to always use the maximum information available when the algorithm can handle it. OpenDroneMap does a fairly good job filtering data and using best available. OpenSfM does a good job with fisheye lenses these days, so I’d lean toward using the full available data. The entire toolchain prioritizes better quality data, so data along the edges of a fisheye will be de-prioritized inherently, but there’s usually no value to throwing that data away a priori.

But, the best way to know beyond theory is an A/B test.

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I had images with distortion and WebODM couldn’t get a acceptable result.

Thanks for your comment. Was it anything like this?

No, less distortion but didn’t work well at all. It was from a DJI phantom.

Did you choose fisheye (if appropriate) as your lens type?

No, it was not that distorted.

You shouldn’t get distortion from a Phantom unless something weird is happening: a brown-conrady model (usually the one chosen in auto-mode) should be enough to fix distortion. Feel free to open a separate thread with the offending dataset if you are seeing distortion with a Phantom.

Edit: is it already discussed in this thread?: About the Website Feedback category

I’ll follow up on that thread later, but you can’t fix distortion with a single line of photos. You need 2 or probably 3 lines of photos to get good results in a corridor.

There’s a setting in the app that fixes the distortion in the drone. So I use that now

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For photogrammetry, I recommend never using in camera/in drone distortion correction, but let the photogrammetric application (OpenDroneMap in this case) do the correction. It seems counterintuitive, but if you use in device correction, you introduce errors that cannot be removed.

Most cameras have that adjustment built in so how do you go around that?

There’s of course some lenses that are built to creep straight lines straight.

You can only turn it off if the vendor lets you turn it off. Otherwise, the camera is probably not a good candidate for anything requiring accuracy.

So what drone candidates do you recommend? Haven’t seen a setting on my Mavic 2 Pro.

A lot do unfortunately. It is useful for making individual shots look better and terrible for photogrammetry. The ideal drone probably doesn’t exist at any reasonable price point. Mavic is among the best fliers. Phantom 4 Pro is among the best cameras, short of a global shuttered Sony.

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