May 23, 2007, HiRISE release |
May 23, 2007, HiRISE release |
Guest_AlexBlackwell_* |
May 23 2007, 04:01 PM
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#1
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May 25 2007, 09:01 AM
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#2
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Thinking about the possible pattern of illumination in the cavern made me think again of that wonderful Pantheon photo. The patch of sunlight in this case might be falling on a horizontal floor, but more likely somewhere part way up one sloping side of the tunnel, thus preferentially illuminating the opposite side with scattered light. I have a sketch of the geometry which could produce the apparent slight grading in interior illumination that may be showing on that image, but unfortunately no easy way of posting it here.
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Guest_Oersted_* |
May 30 2007, 10:55 AM
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#3
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Thinking about the possible pattern of illumination in the cavern made me think again of that wonderful Pantheon photo. Good one thinking of my photo, I didn't even do that, but yes, there are definitely similarities in the spatial lay-out! The patch of sunlight in this case might be falling on a horizontal floor, but more likely somewhere part way up one sloping side of the tunnel, thus preferentially illuminating the opposite side with scattered light. I have a sketch of the geometry which could produce the apparent slight grading in interior illumination that may be showing on that image, but unfortunately no easy way of posting it here. Something like this? My "Pantheon - Earth and Moon-page": http://www.dalsgaard.eu/Pantheon/ |
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Jun 4 2007, 09:55 AM
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#4
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Good one thinking of my photo, I didn't even do that, but yes, there are definitely similarities in the spatial lay-out! Yes, and thanks for the additional image. The only difference between this and my sketched geometry is that I have replaced the spherical internal shape of the Pantheon with a horizontal cylinder representing the inferred lava tube. The internal illumination pattern then depends on the azimuth difference between the illumination direction and the cylinder axis, as well as the sun's altitude. |
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