Judder and drone speed connection?

[so low still grounded]

This question is related to frame rate issues and the camera moving.
What I would like to know from the folks who fly and film a lot is.

Does GPS lock affect the drone/camera speed over time. For example if I fly manual in a straight line then the drone speed should be exponential over time getting faster as the motion escalates? the same as a car freewheeling downhill.
With the GPS on does this in effect keep the drone linear speed constant?

The reason I am asking is when I fly and film by the seat of my pants at certain points I get scan line judder so this has to be motion related because the judder is not constant. When the GPS is on I DON’T SEE THIS. or when I fly at certain speeds GPS ON I also see the scan line judder top to bottom. This then has to be a frame rate and camera motion speed …that is not shutter speed issue but a camera motion speed issue creating scan lines.

Also when you see the scan judder and you then turn the drone 90 degrees the judder immediately disappears because the motion is not across but down as in moving forward filming front and moving forward filming side so the motion is right to left on the clip tells me at certain drone speeds the cam judders . what the speed is I have no idea but would be nice to know.

 

[IrishmanPDX]

1: For example if I fly manual in a straight line then the drone speed should be exponential over time getting faster as the motion escalates? the same as a car freewheeling downhill.
This is only true if your drone is falling from the sky, only then will it exponentially accelerate over time. In level flight however the drone will only accelerate to the limitations of what it's motors can provide. So it's more like a car driving along a freeway. You can only go as fast as the car engine will allow you to. I'm not sure the GPS has any affect on speed, otherwise in the speed settings you would probably be able to select a min to max speed in knots or mph or kph. However you'll notice your speed choice is basically a measurement of slow, medium and fast. With Open Solo there may be barometer feedback so when flying at a fast speed in "Follow me" mode, your drone won't trade off height for speed and fly into the ground trying to keep up with you.

Your "Scan line judder" sounds more like a tearing issue (or jello issue. with can be related to frame rate or an unsteady gimbal. however what you should do is post a clip to youtube so you can let people see what you're describing and see for themselves. A gimbal will offer you nice smooth shots at slow speed, but the faster you go, the more winder buffering it will encounter and have to contend with. With a low frame rate this could add to visual tearing. (again without video to see the issue, it's hard to say).

 

[so low still grounded]

1: For example if I fly manual in a straight line then the drone speed should be exponential over time getting faster as the motion escalates? the same as a car freewheeling downhill.
This is only true if your drone is falling from the sky, only then will it exponentially accelerate over time. In level flight however the drone will only accelerate to the limitations of what it's motors can provide. So it's more like a car driving along a freeway. You can only go as fast as the car engine will allow you to. I'm not sure the GPS has any affect on speed, otherwise in the speed settings you would probably be able to select a min to max speed in knots or mph or kph. However you'll notice your speed choice is basically a measurement of slow, medium and fast. With Open Solo there may be barometer feedback so when flying at a fast speed in "Follow me" mode, your drone won't trade off height for speed and fly into the ground trying to keep up with you.

Your "Scan line judder" sounds more like a tearing issue (or jello issue. with can be related to frame rate or an unsteady gimbal. however what you should do is post a clip to youtube so you can let people see what you're describing and see for themselves. A gimbal will offer you nice smooth shots at slow speed, but the faster you go, the more winder buffering it will encounter and have to contend with. With a low frame rate this could add to visual tearing. (again without video to see the issue, it's hard to say).

Thanks IrishmanPDX your direction and experience is much appreciated.
Will do, let me hunt for a few clips then isolate the issue I am referring to.

 

[RichWest]

Thanks IrishmanPDX your direction and experience is much appreciated.
Will do, let me hunt for a few clips then isolate the issue I am referring to.

I'd be curious to see a video example as well...

 

[so low still grounded]

thanks guys. It appears when solo is going down or up and turning . its almost as if the foreground and background judder back and forth

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[RichWest]

Are these clips post stabilized? Seems that they are as some references in the shot are stable.

When the GPS is on I DON’T SEE THIS. or when I fly at certain speeds GPS ON I also see the scan line judder top to bottom.

GPS OFF (Fly Manual), it doesn't happen and when GPS ON (FLY) it does...is that what you meant? If so, FLY Manual flight will be the smoothest since the gps is not correcting to the location of X&Y.

First blush and disregarding the above thoughts, it appears the gimbal is bouncing on either the front or back dampeners. Curious if you've applied any additional dampening material to the gimbal....i.e. moon gel, ear plugs or other...

Another thought, after market lens? Almost like you have a lens element that is moving.

Strangest effect I've ever seen if not post stab'd or dampened further.... I was impressed that it was 25fps along with the epic scenery... I live in the flat lands....

 

[David Boulanger]

thanks guys. It appears when solo is going down or up and turning . its almost as if the foreground and background judder back and forth

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Can you give more information regarding camera settings? And, like rich said, is there any post stabilization added.

 

[IrishmanPDX]

Hi Folks, watch the clip from about 8 seconds onwards and keep an eye on the rock in the left hand corner. At first glance it seems that the drone is either flying forward or slowly panning left. Then tt looks like the background is getting closer but that rock is staying in the same location. It's almost like there's a digital zoom being applied as the drone is flying backwards. Like a reverse dolly shot. In which case, is the judder we're seeing actually a result of how the clip is being rendered in post? Like it's dropping frames or there's no frame blending between the digital zoom being applied. On the right hand side of the frame the clouds are moving past as if the drone is flying forwards or the scene is being zoomed in, but the rock stays in the same location. If the drone was flying forward, a zoom effect being applied, or the drone was panning to the left, I'd expect movement on both sides of the screen. However at 8 seconds is looks like the rock on the left stops moving while the background and background right are moving towards the camera. If you look at the background left, (the cliffs and clouds) they seem to be moving towards the camera, but not the rock in the foreground. It's like the dolly effect seen in this clip at 5 seconds in is being applied.

If post stabilization is being applied wouldn't that possibly give the same effect?

I think what we need to see is the original footage straight off the card, not something done in post.

 

[RichWest]

I saw the same zoom effect, why I questioned post stab initially. Seems it either rendered some very rough footage or was over-tweaked. The plot thickens.

 

[IrishmanPDX]

I saw the same zoom effect, why I questioned post stab initially. Seems it either rendered some very rough footage or was over-tweaked. The plot thickens.

Thank god, I don't need (new) glasses. My video editing skills are right up there with my hardware skills (duct tape, lots of duct tape), so I hoped what I was saying made sense. Hoping we get an answer on the above or at least some of the original footage for comparison.

 

[RichWest]

I let YT stabilize a video way back when, it was slightly jumpy prior. It looked like it had been placed in a blender once rendered... That was a couple of years back, I rendered a clip recently and it actually improved the results...surprised.... I think it's voodoo magic....

 

[so low still grounded]

thanks so much folks …that’s what it is. Stabilizing issue.

Standard gopro 3.

Being a very lazy video editor I batch encoded and resampled using a separate app with pre-set
Stabilising to a workable h264. Prodrenalin..So I see this is a big mistake with drone footage. I have to encode and resample drone clips like all the other clips. It’s always the short cuts that bleed the most.

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[David Boulanger]

If what you are saying is every individual video clip needs to be stabilized differently I would agree. I have done test where a certain stabilization amount is good for one part of the flight but way over done for other parts.

 

[so low still grounded]

Yes David that’s what I am saying. I would appreciate any direction and some basic insights you may have. I bought a drone because I wanted to add another perspective or aspect to my projects. I have only had my drone less than a year so all the quirks that comes with the footage I will also have to get my head around.