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Hyperlapse issues

hedbonker

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Last Sunday I went out to a local farm where I fly on occasion that borders a freeway. My intention was to fly a path parallel to the freeway over the corn field with the freeway as my primary subject and do a waypoint hyper lapse of the freeway. The framing would include the rows of crops beneath the drone as well as crops on the other side of the freeway. I flew to 211' AGL and over to the first spot for the hyper lapse and set that as a waypoint. I then flew to the last location and set that waypoint.

The camera was set to automatic, 12MP JPG. The total number of images would be 600 and since the 1st waypoint was about 500' away from me and the last one around 1300' from me and the time estimate to shoot the timelapse was about 20 minutes I decided to swap the battery for a fresh one, so I flew it back to me and swapped it out then flew over by the first waypoint and triggered the mission. When it was done, I did an RTH and wrapped things up. Looking at the final assembled hyper lapse at home, it looked decent enough except that the crop fields had an annoying amount of flicker associated with them.

I used a de-flicker plugin in my NLE, but it was no good. Nothing I did would mitigate the effect. I dismissed the issue as being related to auto exposure. I ran exiftool on all the images and generated a CSV with just the exposure data in it (love exiftool) so I could see quickly how much exposure variation was occurring. And, while there was a lot of variations it was not a wide range of settings. Nonetheless I assumed that was the issue.

During the week I did another flight and I noticed that the FLY app had saved the hyper lapse mission for me, so I decided to return to the farm this morning and re-run the mission with a slight variation in that I set the exposure to manual and shortened the duration of the hyper lapse by 2 3rds. I flew the drone over to the area where the hyper lapse would start at the same 211' AGL of the original and told the fly app to run the mission. The done flew to the starting point as expected but then it ascended to 400' and just sat there. NO idea what that was about so I decided to delete that mission and start fresh which I did, and I ran that, and it ran fine.

Looking at the results at home the exact same flickering issue was present. So, the issue is not auto exposure. My questions are:

Why did the drone fly to 400' and then just sit there when I launched the old, saved mission?
Should I use 48MP and raw instead of 12 and JPG? Would that help mitigate the flicker?
Is there a post-production trick I can try to mitigate the flicker? Doing the old trick of offsetting a duplicate of the clip by 1 frame and adjusting the opacity just made it worse.


Thanks!
 
Last edited:
Are you talking about the flicker in the movie produced by the drone?

Or did you use the shots to make the movie in some other program?

Or is the corn field issue more moire?
 
The movie produced by the drone. And, no, it's not moire.
 
The issue is the fine detail between the rows of crops - That is the only spot that has the flicker and it's because of the specific subject matter. I did another one without the farm fields and it was perfect. But this still leaves the question of why it went off the deep end when I tried to replay the old waypoint hyper lapse that I did the week before and had saved.
 
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I don't see anything wrong with that video. Looks completely fine to me.
 
Can you turn the camera sharpening settings down any more?

Was this output to Youtube to 1080?

Looks like a combination of over sharpening made to look worse due to down sampling to to a lower resolution then YouTube compression the heck out of the uploaded file.

Does the original files look the same?
 
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It is aliasing. Look it up, that will explain it better than I can. It IS a type of Moire.
+1

This is due to the fact that the drone has too much sharpness out of the box. OP should go into the settings and reduce sharpness to at least -1, but I would reduce sharpness all the way if you edit your content and can sharpen the content to your liking in editing. This will likely fix issues such as the aliasing mentioned here.
 
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