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Image distortions - Phantom 4
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4023 75 2016-8-10
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buscape
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Hello,
I've noticed something very weird in my videos!
Here is an example. Look at the square in which is the magnifier  

May I return my drone because of this?

Edit: I've added crop animation below.

Lens distortion

Lens distortion
2016-8-10
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Geebax
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I have looked at that clip several times. I have no idea what you mean by 'magnifier' and I also cannot see anything wrong with the image. Perhaps try again?
2016-8-10
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DJI-Jamie
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It's really hard to determine due to the darkness of your surrounding. Do you have another clip? To clarify, how long have you had this unit?
2016-8-10
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buscape
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Geebax Posted at 2016-8-11 01:23
I have looked at that clip several times. I have no idea what you mean by 'magnifier' and I also can ...

Magnifier is the marker actually, because I loaded image from internet which is larger than screen.
The square is in the second row, third column from right to left. In fact, few squares are affected.
2016-8-10
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buscape
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DJI-Jamie Posted at 2016-8-11 01:36
It's really hard to determine due to the darkness of your surrounding. Do you have another clip? To  ...

I can see the problem very well here in this video. But it's better to watch thru larger display. The darkness is not a problem. I've found the issue when I rotated the drone. Most of the time there is a sky in the affected areas and it's not visible. But when the gimbal is tilted down in way that sky is not visible and there are some objects and when I rotate the drone I see some kind of "waving". I removed even the UV filter, but no change. As I can see from another my videos this distorition is symmetric, i.e. there is a same distortion near the left corner, but in this video it is not visible.

I have this drone from the end of April 2016

I'm not at home right now and perhaps I have to prepare more videos and images describing the problem when I get home.
2016-8-10
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buscape
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Again, please look at the third column from right to left.  First two squares at the top. They are like breathing.  They are widening and narrowing!
2016-8-10
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Geebax
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buscape Posted at 2016-8-11 13:49
Again, please look at the third column from right to left.  First two squares at the top. They are l ...

Nope, I can't see a thing wrong with them, could be the monitor you are viewing it on.
2016-8-10
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buscape
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Geebax Posted at 2016-8-11 07:18
Nope, I can't see a thing wrong with them, could be the monitor you are viewing it on.

No, it's not the monitor. I'll make animated gif soon.
2016-8-10
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buscape
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buscape Posted at 2016-8-11 09:21
No, it's not the monitor. I'll make animated gif soon.

Here is the animated GIF

Animated crop

Animated crop
2016-8-10
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Geebax
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buscape Posted at 2016-8-11 16:47
Here is the animated GIF

Odd, I don't see that sort of distortion when I view it. Anyone else?
2016-8-10
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buscape
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Geebax Posted at 2016-8-11 10:02
Odd, I don't see that sort of distortion when I view it. Anyone else?

I can't believe that you can't see it....
The square with the marker (magnifier) gets narrower than surroundiing  left and right squares.And the square above this one is in even worse situation.

The problem almost disappears at the 5th row
2016-8-10
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OrlyP
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I had to watch it a few times to see what the OP was referring to. But it's there.

Very likely a lens aberration.

What's the model of the aircraft?
2016-8-10
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buscape
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OrlyP Posted at 2016-8-11 10:43
I had to watch it a few times to see what the OP was referring to. But it's there.

Very likely a l ...

It's Phantom 4
2016-8-11
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西子果王
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What's the point of magnifying it? Confused.
You convert Youtube to GIF.
2016-8-11
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buscape
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西子果王 Posted at 2016-8-11 12:23
What's the point of magnifying it?

No, I don't simply convert Youtube to GIF.
I focused the problem.  I hope you can see it even without animation.
2016-8-11
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DJI-Paladin
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buscape Posted at 2016-8-11 18:09
No, I don't simply convert Youtube to GIF.
I focused the problem.  I hope you can see it even witho ...

Buscape, I've passed this video to our developers. This is normal and acceptable. Don't worry.
2016-8-11
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buscape
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DJI-Paladin Posted at 2016-8-11 14:08
Buscape, I've passed this video to our developers. This is normal and acceptable. Don't worry.

Thank you!
I've searched on interrnet for videos shot with Phantom 4. But I didn't notice such issue.

2016-8-11
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buscape
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Here are more examples:



2016-8-15
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Aardvark
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That's interesting, am I right in thinking the firmware uses an algorithm to overcome the distortion in the wide angle lens ? This could be a result of it producing the best effort it can from the image (or smoothed out in some future update ?).
Your animation certainly helps, but I think unless you are aware and specifically looking for it then it's difficult to see. Have you tried this filming in 4k ?
2016-8-15
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buscape
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Aardvark Posted at 2016-8-15 12:10
That's interesting, am I right in thinking the firmware uses an algorithm to overcome the distortion ...

I made few videos in 4K when I bought Phantom 4. But there were some flickering issues. As I found, it was because of compression. I didn't research further. I've simply decided to shoot in 1080p.

But I think that, no matter how I shoot, the problem exists, even when I take photos.
2016-8-15
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buscape
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BTW, I haven't found such problem in any other videos on internet filmed by Phantom 4.
2016-8-15
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buscape
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DJI-Paladin Posted at 2016-8-11 14:08
Buscape, I've passed this video to our developers. This is normal and acceptable. Don't worry.

Hi again Paladin,
what did the developers say?

I'm afraid that the image quality is not acceptable for me. I've watched many videos shot with Phantom 4 on internet and I didn't find such problem.

Here is it again my P4:

I'm considering replacement of Phantom 4.
2016-8-24
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jmark_walton
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This may be due to firmware. On first images I took with P4 there was no issue but noticed recent images have needed adjustment to correct various issues as seen in the leaning buildings above.
If I have time over the weekend and weather permitting I may take some test shots then downgrade the firmware and repeat the same shots. This should give an indication if this is firmware related.
You get the same issue with DSLR wide angle lenses but once you load images into applications such as Lightroom they can auto correct this based on the lens information embedded in the image exif data.
2016-8-24
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DJI-Paladin
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buscape Posted at 2016-8-25 02:59
Hi again Paladin,
what did the developers say?

Sorry for my delay but please use "reply" button if you want to remind me of something. Could you please upload the original video file to dropbox and post the link here? The file cannot be edited or transcoded.
2016-8-24
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buscape
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DJI-Paladin Posted at 2016-8-25 04:32
Sorry for my delay but please use "reply" button if you want to remind me of something. Could you  ...

Hi again,
here are today's original videos:

http://aerial360.net/dji-support.zip

I've found that in 4K there are no such distortions?!?! ( DJI_0035.MOV is 4K )
Thanx Aardvark
2016-8-25
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DJI-Paladin
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buscape Posted at 2016-8-25 19:19
Hi again,
here are today's original videos:

Could you upload it to dropbox?I've tried many times but it is almost impossible to download this file. I'm sorry.
2016-8-25
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Crio
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I have the same problem in UL corner.
Im trying to not thinking that its there
Which is not an ideal solution anyway...
2016-8-26
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buscape
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DJI-Paladin Posted at 2016-8-26 10:20
Could you upload it to dropbox?I've tried many times but it is almost impossible to download this  ...

Sorry,
here is the new link:
https://www.dropbox.com/s/o259qauqr73ekm9/dji.zip?dl=0
2016-8-26
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buscape
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Crio Posted at 2016-8-26 11:31
I have the same problem in UL corner.
Im trying to not thinking that its there  
Which is not an  ...

Is it also Phantom 4?
UL = upper left?
Did you check the symmetrical corner for the same issue?
2016-8-26
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DJI-Paladin
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buscape Posted at 2016-8-26 16:49
Sorry,
here is the new link:
https://www.dropbox.com/s/o259qauqr73ekm9/dji.zip?dl=0

I've sent your videos to our FAE team and both the original unedited videos don't have obvious distortions.When a drone flies fast and record some complex scenarios, the videos will behave like this.
But in these videos, the gimbal shakes and tilts a little bit. But it works well when the view stops. I'd suggest you to calibrate the IMU and gimbal then try again.

2016-8-26
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buscape
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DJI-Paladin Posted at 2016-8-26 12:55
I've sent your videos to our FAE team and both the original unedited videos don't have obvious dis ...

For me, there are three unedited videos with obvious distortion (1080-01, 1080-02, and 1080-03).   Only the fourth video (DJI_0035.MOV) doesn't have obvious distortion or at least I don't see it. I think that we don't talk for a same thing.  May be I only had to put ND filter for smoother filming in this sunny day. But for me, the distortions are very obvious when I rotate the aircraft.  I admit that when I fly straight ahead, without rotation they are not visible.

I've made a grid animation, crop videos, I've put arrows showing distorted areas... I really don't know what I have to do more.

I don't talk about normal distortions at the corners which all wide lens do have. This is very weird distortion that I've never came across.

I've already written to the support http://www.dji.com/support/product/phantom-4 and they replied "I have checked you videos and there the issue is visible. It will have to be sent in." Now I prepare RMA. I have ticket digit. But I'm confused that the distortion is not visible for all. I don't know what I have to expect from your service in Germany in this case.

It's very strange that in 4K there is no distortion. May be this is a sign for something.
2016-8-26
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buscape
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Grid example unedited: https://www.dropbox.com/s/7ca72yspn68jj62/grid.zip?dl=0
2016-8-26
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Crio
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buscape Posted at 2016-8-26 10:04
Is it also Phantom 4?
UL = upper left?
Did you check the symmetrical corner for the same issue?

Yes its on P4,
Yes its in upper left corner
and..No, Im afraid to check the other corner
2016-8-27
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hummingbird.uav
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I've seen this in my P4 videos.  Usually shoot in 1080P.  Needs a complex subject to see it, ie not blue sky.  I occurs at both sides of the screen when doing a slow pan while hovering.  Easier to see when playback is on a large screen.
2016-8-27
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buscape
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hummingbird.uav Posted at 2016-8-27 17:26
I've seen this in my P4 videos.  Usually shoot in 1080P.  Needs a complex subject to see it, ie not  ...

Exactly,
thank you for sharing your experience!
2016-8-28
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DirtCreature
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I have the same issue.
Let me know if you need video.

$1,500 for lens distortions isn't sitting well right now.

Thanks!
2016-8-28
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buscape
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DirtCreature Posted at 2016-8-28 22:11
I have the same issue.
Let me know if you need video.

Thank you for your support!
Have  you noticed the same issue in 4K?
2016-8-28
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gmccurdy
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What you see looks like the effect of a rolling shutter that the P4 camera has, i.e. the top and bottom points of any given frame scan are not captured at the exact same moment, which is why images can appear skewed under certain circumstances.  Worse is the Jello effect which happens a lot and will destroy a scene much more than yours.

Look at this image of a harp player taken with a rolling shutter.  You see all sorts of distortions in the straight strings.



Most of the time the issue is some micro-vibrations to the camera's sensor that causes the video lines to skew a bit due to movement.  Some report a prop imbalance as a vibration cause so you might look there and try a prop balancer.  Others report using a slower shutter speed (ND filter) and slowing down their pans help a lot too.

Fwiw, this also happens even with a large Canon or Nikon DSLR in video mode when it resorts to a rolling shutter for capture - and some cost a lot more than the P4.  My Nikon D800E has done it at times when panning or shooting moving objects.  Just annoying effect of that type of shutter and not an indication something is broken in it.

An option is to repair it in post with some software.  After Effects CS6 has a nice tool to fix it.  Here:  http://tv.adobe.com/watch/cs6-cr ... -after-effects-cs6/

2016-8-28
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buscape
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gmccurdy@att.ne Posted at 2016-8-28 23:25
What you see looks like the effect of a rolling shutter that the P4 camera has, i.e. the top and bot ...

In my first post video, with the grid, I moved the aircraft manually without any props on it. And it was dark (i.e. I used slow shutter speed), so the  ND filter was useless.
2016-8-28
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gmccurdy
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With the grid video, you are very close and inside whatever distance the lens hyperfocal distance was set at the factory (I think that lens unit is glued on screw threads for setting focus?).  Factory may set them to an optimum of maybe 100 feet being a f/2.8 lens, so that accounts for the blurriness part.  The wavering movement is greatly exaggerated by shooting so close too hence the scan lines are wavering with the slow speed of the rolling shutter.

If your grid were farther away, better lighting, and a stable means of panning (Not handheld!) you likely would not notice anything.  One of my cheap (loose) tripods will do nasty things when I pan with it on the Nikon, but if I put it on a tighter fluid head it looks a lot better for video.  Photographing an airplane's propellers you'd think the plane's props were bent 180 degrees back and ready to break off!

You could try shooting stills of the grid and see how they turn out.  They will likely be aligned right with the exception of some edge distortion from being a wide angle lens, also correctable in post with software like Lightroom that has the DJI lens corrections in it with the DNG files.  Keep the drone stationary as well as the grid.  That would eliminate the video part in dealing with the shutter.  I think there is also a setting for the Hz scan of Auto, 50, and 60 in the menu.  Changing it off Auto to either 50 or 60 Hz might help too.  Less thinking (resources) for the camera to do.  I don't think I shoot anything in Auto on mine.
2016-8-28
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