...and other stupid sundial tricks.

Take a look at this NASA-calibrated sundial image:

http://tinyurl.com/create.php

Zoomed:



From that image the following RGB values are obtained:

Ambient light (direct + scattered): 200:210:207
Scattered light: 87:72:60
Sky color: 194:169:161

So the direct light (i.e., direct sunlight) would be 200:210:207 minus 87:72:60 = 113:138:147

Scaled to max brightness: 196:239:255 (Sun color)

Here's a graphic showing the sky color (194:169:161) vs. the sun color (196:239:255):



Who knew?

Joe

Well - it's very blue at sunset. Not sure on the maths of what you've done there but it wouldnt at all suprise me.

Doug

This is high noon--check the sundial.

Hey, y'wanna stare at the sun, here, and show us what it looks like?

IMHO, the sun is brighter, bluer than sunlight. Just it hurts to look...


Maybe you need to factor in the extreme Sun filters on L8/R8?

Oh - I know that - I was just saying that a blue coloured sun on mars isnt a new idea.

BUT - i do think you're jumping to conclusions. as we've found with many many sets of images on this thing - we dont really have any clue of the real colours we're actually seing - and you have to account for things like the huge white pillar supporting pancam and navcam a few ft from the sundial that will be casting light onto the dial etc etc.


Doug

Hi Doug,

Maybe you could point to some references on the blue sun on Mars? All I can find is reference to blue sky at sunset, caused by scaterring phenomena, not that the direct sunlight itself would be bluish.

As for the colors in that photo, it's NASA's calibration & so the best available.