[OT] Mars Rover pictures
[OT] Mars Rover pictures
- Subject: [OT] Mars Rover pictures
- From: Tom Beckenham <email@hidden>
- Date: Tue, 20 Jan 2004 15:32:43 +1100
Completely off topic but interesting if you're into color science.
Have any of you been following the "color of mars" issue?
They are a camera they call the "PanCam" on the Mars Rover. It is using some
form of CCD camera with filters that take spectral readings from 400nm to
1100nm. Read about the PanCam here
http://athena.cornell.edu/pdf/tb_pancam.pdf.
I found the description of the calibration of this camera a little
interesting, especially comparing it to how we calibrate Digital Cameras on
earth.
From the PDF above: "Radiometric calibration of both Pancam cameras will be
performed with an absolute accuracy of 7% or better and a relative precision
(pixel-to-pixel) of 1% or better."
Does that mean that there is an error of up to 7%? Surely I have that wrong?
Secondly "Calibration will be achieved using a combination of preflight
calibration data and in-flight images of a Pancam calibration target carried
by the rover. The Pancam calibration target is placed within unobstructed
view of both camera heads and will be fully illuminated by the Sun between
at least 10:00 AM and 2:00 PM local solar time for nominal rover
orientations."
Surely they need a consistent light source to be able to calibrate a camera
like this? Can anyone explain this?
Also check out
http://www.atsnn.com/story/30048.html. There are some links
to some B/W JPEG images that are generated from individual filters on the
PanCam. These correspond to a spectral range. They have instructions of how
to combine the images in PhotoShop to get an RGB composite. NASA have always
said that they were not terribly interested in RGB composite images of Mars,
but I reckon there would be some of you out there that could figure out a
better way to combine these to get a better RGB composite. Have a look see.
Regards
Tom
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