File:Juno's Perijove-04 Jupiter Flyby, Reconstructed in 125-Fold Time-Lapse, Revised.webm

English: On February 02, 2017, NASA's Juno probe successfully performed her Perijove-04 Jupiter flyby. From JunoCam's raw image data, and SPICE navigation data, the movie reconstructs the two hours and 15 minutes from ISO time 2017-02-02T12:00:00.000 to 2017-02-02T14:15:00.000 along Juno's trajectory in 125-fold time-lapse. JunoCam is the Education and Public Outreach camera of NASA's Juno spacecraft. Juno's major science objective is looking beneath Jupiter's impressive cloud tops. In addition, JunoCam gives us a first close look at Jupiter's polar regions at wavelengths of visible light.

The reconstruction makes use of the 13 raw JunoCam Perijove-04 RGB images #97, #99 to #109, and #111. In steps of five real-time seconds, one still images of the movie has been rendered from at least one suitable raw image. This resulted in short scenes from one to about 13 seconds. Playing with 25 images per second results in 125-fold time-lapse. Resulting overlapping scenes have been blended using the ffmpeg tool. In natural colors, Jupiter looks pretty pale. Therefore, the still images are approximately illumination-adusted, i.e. almost flattened, and consecutively gamma-stretched to the 4th power of radiometric values, in order to enhance contrast and color. There are some considerable time gaps between consecutive raw images. This required reprojections of portions of raw images close to Jupiter's limb to a perspective as if the camera would have been above this surface area of Jupiter. This resulted in a degraded quality of some portions of the movie.

The movie starts with a resonstructed in-bound sequence approaching Jupiter from north. Then the orbit approaches Jupiter down to an altitude of about 4,000 km near the equator. This is followed by a transition into the outbound orbit, during which Jupiter's south polar region comes into view. Rendering the still images of the movie took about four days on one up to three virtual CPU cores running in parallel. The rendering software for the stills is proprietary. Trajectory data were retrived from SPICE kernels with the SPICE/NAIF tool spy.exe. from For combining stills to movie files, the tool ffmpeg has been used. Blending may result in feature-doubling in overlapping scenes due to reprojection inaccuracies, and to some fast shifts of quality and/or color. Most repetitive bright and dark camera artifacts are patched. Due to the intense radiation near Jupiter, some additional bright pixels occured, visible in the stills the movie is rendered from, at least. Those aren't patched in this animation. In rarer cases, lightnings on Jupiter might also show up as bright pixels. Sometimes, the edges of the raw images show up as black triangular areas in some corners of the movie rendition. During blending, features may be doubled due to alignment inaccuracies of the blended scenes. Some of the very close-ups show block artifacts as a result of lossy compression within the camera, which has been necessary due to limited storage. Cloud motions are probably too tiny to be perceptible from this distance, and within the short time. Any residual issues in the movie are due to imperfect image processing.

The movie may nevertheless provide you an idea of Juno's Perijove-04 flyby.