Re: [APML] OT: "True Color" Mars Mosaic

["Bobby Middleton" <bobm@koyote.com>]

Very cool Chuck.
Bobby M

----- Original Message ----- 
From: "Chuck Vaughn" <aa6g@aa6g.org>
To: <astro-photo@seds.org>
Sent: Thursday, February 05, 2004 1:29 PM
Subject: [APML] OT: "True Color" Mars Mosaic


> List,
> 
> Here's my best guess at what the outcrop at the Opportunity site really 
> looks like.
> 
> http://www.goldrush.com/~aa6g/Images/outcrop_cal.jpg  (450KB)
> 
> Here's what was done:
> 
> 1) Assembled a tricolor with rover solar panels in the image and 
> calibrated the image so that the panels were neutral dark gray. They 
> look black in every photo we've seen so I assume that is correct. 
> Here's that image:
> 
> http://www.goldrush.com/~aa6g/Images/soil_calibration.jpg  (115KB)
> 
> 2) Sampled the soil to get the hue and saturation. If you don't get 
> these close the color will be way off.
> 
> 3) There's a bounce mark in the lower left corner of the outcrop image. 
> The JPL scientists have said that bounce marks are revealing the soil 
> under the hematite. They also said the hematite concentration is 
> extremely low where the rover is sitting. So I made a leap of faith and 
> said the soil at the rover is the same color as the soil under the 
> bounce mark. So the first image on the left was adjusted as such.
> 
> 4) Successive images were adjusted to match the first.
> 
> 5) The resulting sky was blotchy mess of oranges and pinks because the 
> original images have slight vignetting and adjusting the green and blue 
> channels accentuates the problem. So I chose  a representative sky 
> color at the horizon and at the top of the image and used the Photoshop 
> Gradient tool to create an even sky that becomes less orange as you go 
> up.
> 
> 6) Desaturated any blue rocks.
> 
> Maybe someday NASA will get around to making their own and I'll see how 
> close I got. The plains in the background do remind me of the those 
> large dark areas in images of Mars from Earth.
> 
> Enjoy!
> 
> Chuck
> 
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