Re: Mir images, (off topic)

From: Thomas A. Troszak (
Date: Mon Jun 25 2001 - 08:07:36 PDT

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    Jonathan T Wojack wrote:
    > Are the two images of Mir depicting the slain space station in the same
    > orientation (just curious) ?  The orientation of the dots seem to be the
    > same in both images.  Or is it the same image twice, with the one of the
    > left with enhanced contrast and brightness?
    Dear Jonathan,
    It is the same image twice.  The good image on the left is the original,
    excellent image sent to me by Bob Citron.  The worse looking one on the
    right is the same image with the brightness and contrast turned DOWN.  I
    purposely degraded the image to demonstrate that on lesser quality
    original images (like mine, for example) parts of the station may not be
    visible, thereby potentially confusing attempts to positively identify
    the attitude of the station.
    Bob's image shows amazing detail, and is due largely to the extreme
    sophistication of his equipment and technique.  If I had attempted and
    image at the same time and place with my basic equipment, I would have
    been very lucky to have acquired an image more like the one on the
    right, or perhaps just a blob of light, due to the complex appearance of
    the station in that particular position and lighting conditions.
    In my attempts to positively identify the attitude of Mir or ISS in my
    own images I aquired a couple of the plastic models of Mir, and even
    went so far as to construct a basic  "tube and cylinder" 3-d model of
    Mir in Autocad 2000.  I found that poor seeing conditions combined with
    the drastic effects of ever-changing conditions light and shadow on the
    station in various attitudes can easily cause large parts of the station
    to disappear, while others appear prominent.
    The photo on the right  was adjusted by less than 20 percent, and notice
    how one of the solar arrays disappears completely.  The remaining array
    could then easily be mistaken for the "boom" which would then cause the
    interpretation to be off by 90 degrees in two axis.
    The results of my studies indicate to me that capturing any satellite in
    a favorable lighting condition and attitude is potentially more
    important to the final image than the quality and sophistication of the
    imaging equipment, meaning that if one were to "get lucky" with a
    favorable pass one could acquire good images with very little equipment,
    and this has been demonstrated recently with some amazing photos taken
    with a webcam:
    Notice how the favorable orientation makes the features of the station
    distinctly visible, and how if the station had been turned 90 degrees,
    it would have been reduced to a simple streak of light due to the fact
    that most of the features of the station are fixed in the same plane.
    Tom Troszak, Technology
    Asheville, NC, USA
    35.601 N, -82.554 W
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