1. Mick West

    Mick West Administrator Staff Member


    Source: https://www.youtube.com/watch?v=_TeJiwMAAgE
    Original video here.

    This video of the sun happens to catch a plane flying in front of it. You can see the heat from the engines distorting the image.

    20170817-212529-22a18.
    But a few seconds later you can also see another ripple pass over the sun. It's a quite thin local discontinuity, so I suspect it's the core of the wingtip vortices.
    20170817-212556-21ebl.
     
    Last edited: Aug 18, 2017 at 9:26 AM
  2. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Must try this myself as I am all tooled up for the solar eclipse and am not going to get much! Fujifilm S1 x100 with baader solar filter sheet. DSCF4689.JPG
     
  3. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

  4. Mick West

    Mick West Administrator Staff Member

    cak_colormap.
    https://www.nasa.gov/feature/ground-based-schlieren-technique-looks-to-the-sun-and-moon


    Patent here actually references what we are seeing in the OP:
    http://patft.uspto.gov/netacgi/nph-...9,599,497.PN.&OS=PN/9,599,497&RS=PN/9,599,497


    The idea in the patent is relatively simple:
    • Video the sun with a calcium-K optical filter to get a nice textured image.
    • Stabilize the video
    • Use some kind of change detection algorithm to detect changes between a reference image (a frame of the sun with no plane or shock wave) and each frame of the video.
    You could probably do a very simple version of the latter by just subtracting the reference frame from the video frame. We could do this with the OP videos.
     
  5. Mick West

    Mick West Administrator Staff Member

    Done!

    Source: https://www.youtube.com/watch?v=sCWRGM4YvNo


    Not a huge improvement though. The atmospheric distortion is rippling the image a lot, so you get a flickery ring around the sun.

    20170818-081434-lwthy.

    20170818-081538-g118q.

    Methodology:
    • Stabilize motion in Adobe After Effects using the sunspot as a reference point
    • In Photoshop, subtract a still frame from the video
    • Add a levels adjustment to brighten everything up
    20170818-082224-fhwr3.
     
  6. Clouds Givemethewillies

    Clouds Givemethewillies Active Member

    Reminds me of methods of obtaining an audio impulse response using noise and deconvolution. eg MLS.