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  1. Justin Shaw

    Justin Shaw New Member

    MTO Aerial has posted a video showing a pair of white streaks traveling in parallel across the sky moving very quickly. First off, is there any known cause for this phenomenon? If not, I'd like to analyse the speed by comparing the difference in parallax of the two objects. Any thoughts?


    Source: https://www.youtube.com/watch?v=Oe-os6llmig

    upload_2018-8-28_7-58-35.
    upload_2018-8-28_7-57-49.
     
  2. Trailblazer

    Trailblazer Moderator Staff Member

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  3. Trailblazer

    Trailblazer Moderator Staff Member

    The video seems to increase in resolution shortly after the objects "launch", which makes it hard to see them for the first few frames. But it looks as though they originate from just below the curve in the road on the far shore. There is a wide parking area/viewpoint here, visible in the video as a light area where the objects seem to come from. Maybe someone taking a pot shot at the drone?

    upload_2018-8-28_14-7-33.

    upload_2018-8-28_14-4-15.

    Assuming the objects did come from here, that is roughly half a mile from the location of the drone, and the time from when they were first visible to when they passed the camera is about 2.5 to 3 seconds, which would imply a speed of about 600-720 mph. That is of course assuming that they were visible as soon as they left the road. A lot of assumptions!

    If we knew the shutter speed of the drone camera then the length of the streaks could also give an estimate of speed.
     
    Last edited: Aug 28, 2018
  4. Mick West

    Mick West Administrator Staff Member

    I dowloaded the full 4K video, they are quite clear in the first frame
    Metabunk 2018-08-28 07-32-24.

    I suspect that they are small rather than far away. The initial movement seems to me to suggest a ballistic trajectory from here
    Metabunk 2018-08-28 07-47-09.
     
  5. cloudspotter

    cloudspotter Senior Member

    I've been too distracted with trying to work out what's going on with the birds in the water in the foreground
     
  6. Mick West

    Mick West Administrator Staff Member

    Like:
    Metabunk 2018-08-28 07-53-46.

    There's several people walking around on there. Slingshot of white rocks? Dubious. The initial upwards apparent movement might just be a compression glitch.

    But it's a wide angle. That area is not as far away as it seems.

    It's three streaks, not two.
    Metabunk 2018-08-28 07-57-23.

    The top object is thicker, then the bottom object seems to be two smaller objects.
     
  7. Trailblazer

    Trailblazer Moderator Staff Member

    If you have the full resolution video, can you overlay it frame by frame to show the track of the objects? The forward motion of the drone will complicate that, of course, but the distant shorelines don't move much.
     
  8. Trailblazer

    Trailblazer Moderator Staff Member

    Yes, my eye was drawn to them first of all so I totally missed the "UFO". I think they are pelicans.


    Source: https://www.youtube.com/watch?v=JmobOctADis
     
  9. Mick West

    Mick West Administrator Staff Member

    Attached is a zoomed crop of the start region. The movement of the figure on the sand behind the rocks is consistent with kids running away after shooting rocks at a drone. It's also consistent with hundreds of other random possibilities.
    Metabunk 2018-08-28 08-11-59.
     

    Attached Files:

  10. Mick West

    Mick West Administrator Staff Member

    I exported as frames, imported as layers, used "Difference" blending

    [​IMG]

    Some of the irregularities are going to be due to the drone motion.
     
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  11. Mick West

    Mick West Administrator Staff Member

    It's 29.97fps, so you can just take the streak plus a gap as the movement in 1/30th of a second.
     
  12. Mick West

    Mick West Administrator Staff Member

    Consider where the midpoint of the path is. The three arrows here are the start, middle, and end of the visible segment in terms of time.
    Metabunk 2018-08-28 09-14-34.
    If we move the start and middle next to the end for size comparison:
    Metabunk 2018-08-28 09-18-01.
     
  13. Trailblazer

    Trailblazer Moderator Staff Member

    It doesn't look as if there's enough "up and down" movement to be a ballistic flight from that nearby spit of land, but that could be an illusion due to perspective I suppose? Edit: I see what you mean, if you take into account where the mid-point is, then it makes more sense.
     
  14. Mick West

    Mick West Administrator Staff Member

    What if it's a lot closer? It does not really seem to get much larger at the closest point. Maybe the path it takes is more like:
    Metabunk 2018-08-28 10-36-55.

    Metabunk 2018-08-28 10-37-21.
     
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  15. Trailblazer

    Trailblazer Moderator Staff Member

    That seems to make more sense if it was something launched from the spit, as the steeper upward part of the trajectory would have occurred before the start of the video, so the part we see is flatter. I wonder if there's a reason why the video uploader didn't include a few seconds more at the beginning? It would be useful.

    Something else that is puzzling me is that the objects seem to keep perfectly stationary relative to each other as they fly. If it was rocks fired from a catapult or something like that then I would expect them to diverge more than that. (Edit: and also the range to the drone location from the end of the spit looks to be 300-400 yards, which is surely beyond the range of a slingshot?)
     
  16. Mick West

    Mick West Administrator Staff Member

    What if it's tiny, like a couple of bits of white fluff just floating in the wind?

    Here I took a wide angle shot of a 120cm long piece of wood, with markings every 10cm

    Metabunk 2018-08-28 11-09-43. Metabunk 2018-08-28 11-10-49. Metabunk 2018-08-28 11-11-34.

    Middle arrow is the midpoint of the path.
     
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  17. DavidB66

    DavidB66 Member

    I have watched this several times at 1/4 speed on YouTube, and I find it very difficult to identify just where the 'UFOs' appear from. As far as I can judge, they are not coming up from the ground; they just materialise out of thin air. Also, I don't see it stated anywhere how high and how fast the drone itself is flying, but judging by its motion relative to the water below, it is going at a fair lick. The Phantom 4 drone (the type said to be used) has a max speed of over 40 mph, so if the white objects are in fact small and near, their apparently fast motion towards the end of the clip may be due mainly to the motion of the drone itself. Though I must admit this doesn't explain their apparent motion across the field of view.
     
  18. Justin Shaw

    Justin Shaw New Member

    This is beautiful. I think I can gauge the speed with this. It may be necessary to know the separation between the points.
     
  19. Mick West

    Mick West Administrator Staff Member

    There are there right from the first frame. Try watching in 4K, full screen. This is from the first frame.

    [​IMG][/QUOTE]

    Their movement is essentially linear, so could be entirely accounted for by the movement of the drone. More likely it's a combination. [Edit] On reflection, I think the objects actually have to be moving, as the drone seems to be moving along the camera axis.

    I'm leaning towards them being vastly closer to the drone than they appear at the start.
     
    Last edited: Aug 28, 2018
  20. Gerard

    Gerard New Member

    Note that in the YouTube description for this video it is stated "The video shows it twice, first at regular speed then in slow motion."

    In fact the entire event occurs between frames 1 and 97 (last regular frame in which the objects are still visible).

    It might be helpful if the original drone video could be obtained from the person who captured this footage. Since the objects only consist of a few pixels (except for the motion blur) compression artifacts may be making a significant contribution to their appearance and reencoding to VP9 certainly doesn't help.
     
  21. Mick West

    Mick West Administrator Staff Member

    This is the best quality shot I could get of the last frame
    Metabunk 2018-08-30 06-15-53.

    At first this looks like "rods", motion blur and hyper rapid wing flapping, the "flapping" is probably just be compression artifacts. And what flaps its wings 8 times in 1/100th of a second? 800 beats per second is ten times faster than the fastest hummingbird.
     
  22. Trailblazer

    Trailblazer Moderator Staff Member

    Could the "flapping" possibly be caused by an irregularly shaped projectile spinning rapidly? It seems to me that it could, but I agree they are more likely just artifacts.
     
  23. Mick West

    Mick West Administrator Staff Member

    Interesting suggestion:

    Source: https://twitter.com/TheOutThere2016/status/1035203468309352448


    Rolling shutter making the "motion blur". One thing I could not figure out was why the white would stay so bright with motion blur, and why the "wings" would be visible at all. But with rolling shutter it makes more sense.

    With rolling shutter, the pictures is scanned down one line at a time, so an object moving rapidly diagonally down would appear as a diagonal line from the time the shutter overtook the object to the time it got past it.

    However, I'm not sure it the length of the streaks works for this. It would seem like they would be shorter, as they only occupy about 1/10 or less of the vertical frame between streak starts, and 1/20th visible. Hmm...
     
    Last edited: Aug 30, 2018
  24. Trailblazer

    Trailblazer Moderator Staff Member

    Looking at the closer streak, in that close-up it seems to be not two separate white objects, but a single object with a dark/black centre and white either side.

    That could fit with the bird idea. The other birds visible in the foreground appear to be black and white (although if they are pelicans, they have white bodies and black wingtips, which seems "the wrong way round" to fit that pattern).

    Again, though, it could be compression artifacts, as there is a similar dark colour in the blocky areas around the streak.
     
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  25. deirdre

    deirdre Moderator Staff Member

    unless its two birds, one slightly below the other.


    upload_2018-8-30_13-56-15.
     
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  26. Trailblazer

    Trailblazer Moderator Staff Member

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  27. Mick West

    Mick West Administrator Staff Member

    The streaks seem to occupy about 1/3 a frame in terms of what portion of the path is visible. That means that the camera was approximately exposing the object for 1/90th of a second and not exposing it for the next 2/90th of a second. I can't quite see how that would work with a rolling shutter - but perhaps it's a combination of blur + roll.

    Here's a good one:

    Source: https://www.youtube.com/watch?v=g6RwVPoXVrQ


    Composite image
    Metabunk 2018-08-30 11-31-40.

    This shows that a reasonably bright object over a dark background can leave a fairly solid streak. In the golf video it's overcast, but the Bodega Bay video is bright sunlight.
     
  28. Justin Shaw

    Justin Shaw New Member

    Thank you Mick for capturing the locations. I found the center of the object in each frame for the last 17 frames and compared the positions to a straight line trajectory ensuring that the first and last points are the same and that the ratio of distantances is constant.

    Comparing the linear track to the recorded track shows a significant offset that I am interpreting as acceleration.

    The drone appears to be flying straight and level, but we could confirm that bu tracking a few ground points through the field of view.

    Justin



    Animation below shows red dot taken from object locations from the video frames, and blue dot showing the straight line constant speed trajectory. While the traces are almost identical, the red dot appears to be moving faster intially, then slowing near the end of the animation.

    https://photos.app.goo.gl/ZqnktyfNLLNMvpmA8
    image.
     
  29. Esdeve

    Esdeve New Member

    Well, slowing down because of air friction, isn't that what a projectile is supposed to do after being shot ?
    Maybe it would be the same visual effect if it were a ballistic shot from the camping like proposed earlier, not sure about that, if someone can finally discredit one or the other theory with that ... thought I already think it's coming from the shore near the road too.

    Maybe change of speed is what makes some people perceive them to appear out of thin air like said on this forum too.

    Would have been great if the drone pilot could follow them with the camera and be able to pick up them later if possible ^^'
     
  30. brentm

    brentm New Member

    Could it be artifacts from scratches in the anti-reflective coating on the lens of the camera?

    The objects are the same color as the drone shell. And it's a gorgeous day out there on the water with reflections coming in at all angles from below. The objects, when they appear on land, seem to stand still a moment before they streak across. It looks like they're moving very fast and there's no sonic boom.

    White fluff is a possibility too - but I'd think the propwash would shoot fluff downward.