Wow, I'm really impressed with what you're able to do with the black and white images with no color information. You both certainly have a good artistic eye for this!
I'm struggling with how best to present the sky images with context as to where they're looking, and where the sun is at that point in the day. As Doug mentioned in another thread, we really haven't seen images of the whole sky, but they do take repeated sequences of 2 or 3 images aiming at certain points in the sky, over multiple sols.
We've got millions of pixels of horizon sky, and much less looking up at various angles, and various times of day. One way to present what we do have might be a polar projection centered on the zenith with the circle representing the whole sky. Any thoughts on what would be helpful for you in your imaging work in this regard?
The changes over the course of the mission, for both rovers, seems to be fairly significant as well. Between seasonal changes, and dust levels dropping as the missions progressed (at least over the first 270 sols), the gradient appears to become much sharper (very bright near the sun, and getting dark quickly as you move away from the sun). For sols 180-270, the images of the horizon facing away from the sun for both Spirit and Opportunity show a sky darker than the ground. It is quite a striking and somewhat foreign concept. I'm hoping the projections of the sky will present this effect more clearly than I can with words.
Finally, a word of caution with regards to the colors I have on my site for the sky. I have less faith in them than I do with the colors of ground objects for a couple reasons. First off, the 3 filter formula I'm using are 'trained' to get as many pixels right as possible, and since the sky isn't imaged as much, the training doesn't weight them as heavily as the ground objects. I'm hoping to get something worked in shortly that'll lessen this effect, by training different equations specifically suited for the contents of the image. With that, I'll be putting up a large number of other sky images which aren't there already, the L3 L5 L7 combos. As of right now, they're coming out quite bizarre so I didn't post them up at all.
Secondly, those images which are very close to the sun end up being rescaled automatically for brightness. Spectrally, the sun itself and the area around it turns out heavier in the blue spectrum than any of its surroundings, but in reality the human eye looking at that part of the sky would bleach the colors to white. Images like
this don't deserve to have a hue at all in terms of what we'd actually perceive, so take them with a big grain of salt.
, but quickie it wasn't possible else.
