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Fixing Mavic Air video lens distortion in post
2810 15 2018-9-19
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jetto black
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Hi all,

I Googled this issue but didn't come up with any solutions.

After upgrading from a Spark to a MA, I've noticed a pretty severe "moustache" shaped lens distortion in the MA's recorded video. It is most apparent when you have the horizon about 1/3 from the top of the frame and do a yaw or horizontal pan. It's much less objectionable when the horizon is on the vertical center or below. There are several threads here related to this, and it appears to be "normal" for the MA.


I've tried some video editing software with lens distortion correction filters, but they seem to assume the lens will have constant distortion across the frame (either barrel, pincushion, or fisheye distortion), while the MA's lens distortion is more complex and not constant across the frame.


There are some photo editing software that can remove this distortion in the DMG files shot by the MA, but I haven't found anything for video files.


Has anyone found a video editing software or filter that can remove this distortion?

Thanks.


2018-9-19
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HereForTheBeer
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i do not have such severe lens distortion, when i look ta my DNG raw file for photos (no in camera/body correction applied) the only distortions i seen were on very far corners.  

can you post same images of something symmetrical like a brick wall that taken on the mavic air with said distortion... take the  photo in DNG raw on mavic air then export it on your computer to .JPG and post it here.. i can and others maybe able to comment better, and point you the right way..
2018-9-19
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jetto black
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HereForTheBeer Posted at 2018-9-19 12:10
i do not have such severe lens distortion, when i look ta my DNG raw file for photos (no in camera/body correction applied) the only distortions i seen were on very far corners.  

can you post same images of something symmetrical like a brick wall that taken on the mavic air with said distortion... take the  photo in DNG raw on mavic air then export it on your computer to .JPG and post it here.. i can and others maybe able to comment better, and point you the right way..

Here's a short video. You can see the horizon has a slight "mustache" shape (lower at the center, higher to the left and right of center, and lower again at the edges of the frame). As the camera pans you can watch the buildings seem to move up and down like an ocean wave. Not everyone will notice this on first glance, but once you notice this, it's very hard to un-see it.



You can't see at all it in the JPGs saved by the MA because it corrects the distortion in stills. The DNGs have lens profile data inserted by the MA so most programs will use that to correct the distortion. You can only see it in the DNGs if you view them in a program that can disable the automatic lens correction profile.
2018-9-19
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HereForTheBeer
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jetto black Posted at 2018-9-19 13:16
Here's a short video. You can see the horizon has a slight "mustache" shape (lower at the center, higher to the left and right of center, and lower again at the edges of the frame). As the camera pans you can watch the buildings seem to move up and down like an ocean wave. Not everyone will notice this on first glance, but once you notice this, it's very hard to un-see it.


i know applications like Lightroom you can import DNGs and disable any profiles then save as a .JPG  i cannot confirm any other applications other than lightroom and photoshop where you can do this in..but i am sure maybe some other options...

the reason im asking for a still frame facing a symmetrical pattern like a level even brick wall is it makes it far more apparent what is really going on and distortion is.  i can sort of see it in your video to me looks like your lens distortion is more bowing the image, like upper center looks closer to frame than the rest.   but it makes it much easier to see the way i asked for to identify total distortion..  you may have a lens fitment issue from the factory, some early mavic airs had this issue where either unfocused spots or bowing

2018-9-19
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jetto black
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HereForTheBeer Posted at 2018-9-19 13:24
i know applications like Lightroom you can import DNGs and disable any profiles then save as a .JPG  i cannot confirm any other applications other than lightroom and photoshop where you can do this in..but i am sure maybe some other options...

the reason im asking for a still frame facing a symmetrical pattern like a level even brick wall is it makes it far more apparent what is really going on and distortion is.  i can sort of see it in your video to me looks like your lens distortion is more bowing the image, like upper center looks closer to frame than the rest.   but it makes it much easier to see the way i asked for to identify total distortion..  you may have a lens fitment issue from the factory, some early mavic airs had this issue where either unfocused spots or bowing

Here's one, not taken by me, but from the Mavic Pilots forum:

DJI_0011.JPG

Link: https://mavicpilots.com/threads/mavic-air-lens-distortion-creating-awareness.35548/

At first it looks like barrel distortion only, but the center of the picture is also pinched inwards, like pincushion distortion.

Again this is easy to fix on still images so it's not a big deal, I'm looking for a way to fix this in videos (without having to export the video as a sequence of stills!).

2018-9-19
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HereForTheBeer
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jetto black Posted at 2018-9-19 13:35
Here's one, not taken by me, but from the Mavic Pilots forum:

[view_image][view_image]

yes this example is very aggressive barrel distortion and edge fall off..extremely in fact.   yours from looks of it from video doesn't experience so much fall off  but you do have pin cushioning and barrel distortions to some degree.   mine is very level i just put mine up in the air and checked my horizon and see if i have distortion and its very level and even compared to even your video example.

the issue you are having mostly affects early models of the mavic air, and in my experience early models can still be in warehouses and circulation. you may have just gotten one before revision where made..

i suggest you contact dji support directly tell them the issue,give them examples and pictures.. if you are within store return/exchange period.. do that instead...  if not then request dji warranty it...
2018-9-19
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devilsBastard
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Hi jetto black.
In the video editing software Premiere Pro and After Effects there are several distortion filters that may help you. If I remember correctly, there a some preset filters for DJI drones. I am satisfied with the results. You can correct the settings manually.
2018-9-20
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jetto black
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HereForTheBeer Posted at 2018-9-19 15:04
yes this example is very aggressive barrel distortion and edge fall off..extremely in fact.   yours from looks of it from video doesn't experience so much fall off  but you do have pin cushioning and barrel distortions to some degree.   mine is very level i just put mine up in the air and checked my horizon and see if i have distortion and its very level and even compared to even your video example.

the issue you are having mostly affects early models of the mavic air, and in my experience early models can still be in warehouses and circulation. you may have just gotten one before revision where made..

Hi HereForTheBeer, I was under the impression all MAs had this distortion, but your post gives me some hope (or worry) that some are worse than others.

Could you do me a favor and post a short video like mine from your MA?
* Video mode
* Horizon at 1/3 from the top of the frame (this is important because the distortion doesn't happen at the center of the frame)
* Some buildings or other objects that make it easy to see the distortion
* Pan left or right like in my video

If yours is truly less distorted then I'll use this as evidence to get DJI to fix mine.

Thanks!
2018-9-20
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HereForTheBeer
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jetto black Posted at 2018-9-20 07:59
Hi HereForTheBeer, I was under the impression all MAs had this distortion, but your post gives me some hope (or worry) that some are worse than others.

Could you do me a favor and post a short video like mine from your MA?

ya, sometime this weekend when im less busy ill try to get a video like your asking for.  if nothing else ill get a snippet of video i already have or one i can quickly do.

edit: what resolution and frame rate?   i just pulled up a 1080P 60fps video i did today (by mistake) and has terrible warping moving left to right on all 4 corners in same way yours does but a bit more agressive infact!  but i checked my 4K 24fps videos and completely gone or unnoticable in handful of clips.....  

this is getting more interesting, tomorrow or sunday imma try to get a few videos to figure this out.  appears for me atleast 4K 24fps little to no warping but 1080P is almost broken levels of bad


2018-9-21
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HereForTheBeer
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mine does appear to have some minor barrel distortion which i havent noticed before so im curious to figure it out... but its far less in 4K 24fps vs 1080p 60fps.. i wonder why.   

2018-9-22
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jetto black
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HereForTheBeer Posted at 2018-9-22 14:10
mine does appear to have some minor barrel distortion which i havent noticed before so im curious to figure it out... but its far less in 4K 24fps vs 1080p 60fps.. i wonder why.   

https://www.youtube.com/watch?v=5gscKwKalaI&feature=youtu.be

Thanks for trying it, but to me it looks about the same as my Air. I think it's less obvious in your shot just because the buildings in yours are more flat and the mountains obscure the horizon line.
2018-9-22
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HereForTheBeer
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jetto black Posted at 2018-9-22 16:38
Thanks for trying it, but to me it looks about the same as my Air. I think it's less obvious in your shot just because the buildings in yours are more flat and the mountains obscure the horizon line.

yes, but i see it as obvious as day now, but i never noticed it before..  i wonder why...

can you do a 1080P video and compare it to your 4K video?  dont need to upload or anything, just to your eye.    on mine my 1080P looks really bad warping on my computer.. 4K looks way better still there but less noticable.  if that's true on yours as well, maybe an issue with where focal point is on the lens since lower resolution is sampling less of the sensor, and smaller and smaller point in the middle.
2018-9-22
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Rob_S
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Thanks for making me aware of this.
2018-9-22
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user740dacf6e5
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HereForTheBeer Posted at 9-22 16:48
yes, but i see it as obvious as day now, but i never noticed it before..  i wonder why...

can you do a 1080P video and compare it to your 4K video?  dont need to upload or anything, just to your eye.    on mine my 1080P looks really bad warping on my computer.. 4K looks way better still there but less noticable.  if that's true on yours as well, maybe an issue with where focal point is on the lens since lower resolution is sampling less of the sensor, and smaller and smaller point in the middle.

Hi, how do you solved the problem? I have the same issu .Thanks

2018-11-6
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HereForTheBeer
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user740dacf6e5 Posted at 11-6 14:53
Hi, how do you solved the problem? I have the same issu .Thanks

for me it is less noticeable in 4K 24 fps, its more noticeable in 1080P 60fps.  


i think you will have to edit the video afterwards and run some lens correction, in maybe adobe premier..
2018-11-6
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jetto black
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I finally found a good free solution that I'm happy with.  The free version of Davinci Resolve 15 (or 16 beta) works fine for this correction. In the Fusion tab, add a Lens Distort node (under Effects Library > Tools > Warp), and change these 2 values:
Distortion: -0.062
Quartic Distortion: 0.088

Leave the other values as-is.

You may also want to crop the video slightly to hide the blank canvas areas created at the edges. I added the Transform node and set the Size to 1.01.

Resolve is a really nice editor, especially for a free program that works on Windows, Mac, & Linux.
2019-4-17
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