Himawari Options

[scalbers]

Here is a real-time full color view of the Earth from the Himawari satellite, updated every half hour or so. This geostationary weather satellite is stationed over the longitude of Japan. The view is complete with orange sunglint off the ocean. You can click on the link to see the latest update.



http://www.jma.go.jp/en/gms/largec.html?ar...=1&mode=UTC

I previously posted this high resolution sample image in the Whole Earth Images thread. We can look around for the full resolution real-time data archive that would be about 11000 pixels wide.

[Dan Delany]

Hi all! Recently I have been experimenting with applying optical-flow-based motion interpolation to earth-observing satellite images - ie. guessing intermediate frames to make smoother videos with artificially higher framerates. I found two open source software libraries which estimate optical flow using different algorithms, and both seem to perform fairly well - slowmoVideo which implements the Kanade-Lucas algorithm, and Butterflow which implements the Farneback algorithm.

I downloaded all of the high-resolution full-disk images from the RAMMB link posted upthread and have been testing the two libraries on cropped regions and short timespans from this dataset. For each method, I started with a 6 FPS video generated from the underlying images. Then I applied a 0.5x speed stretch and motion-interpolated the results to 60 FPS, resulting in a "20x interpolation" - ie. 1 out of every 20 frames is a real image, the other 19 are interpolated.

Here is a comparison of the two methods, using one day of data which show the twin typhoons Goni and Atsani in the Pacific. The images used are 1920x1080 pixels, so make sure you force the quality to "1080p60" for best viewing: https://www.youtube.com/watch?v=Skk58D3waQg

As you can see, the results seem to be pretty comparable during the daytime, when lighting conditions are fairly consistent from frame to frame. However, the Butterflow (Farneback) method appears to handle the dynamic lighting conditions near the terminator around the time of local twilight much better than the slowmoVideo (Kanade-Lucas) method.

Note that the speed of rotation appears to "jump" a few times - this is because most original frames are taken once-per-ten-minutes but there are a few frames missing, and I'm not correcting for this. Next on my to-do list is to handle this more gracefully by generating interpolated frames for the missing frames before performing the full 60 fps interpolation.

Overall I'm quite happy with the results - they may not serve any scientific purposes but they sure are pretty. I think I will produce some more videos using the Butterflow library once I handle the missing-frames problem. I may also integrate it with typhoon track data to produce "typhoon tracker" videos centered on the typhoons as they move around, but this would require a method for getting pixel location from lat/long, which would require reprojection, which I'm not sure if I have enough data for. This is my first attempt at motion interpolation, so any feedback or suggestions would be greatly appreciated!