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jumpjack
2007-Oct-02, 10:56 AM
How can I know the direction from which the sun light comes in this photo?

http://lc84.altervista.org/marte/imm...ake-2-edit.jpg (http://lc84.altervista.org/marte/immagini/mars-lake-2-edit.jpg)

The PDS label (http://hirise-pds.lpl.arizona.edu/PDS/RDR/PSP/ORB_004800_004899/PSP_004847_1745/PSP_004847_1745_RED.LBL)only specifies vertical angle: what about the horizontal one?!? Does the light come from left, right, down, downleft...?

And how can I know the spacecraft longitude with respect to the crater? Was it to the left or to the right of it while taking the picture?



All of these data are needed to properly estimate hole's data (dept, slope,...)



Any help?

StupendousMan
2007-Oct-02, 12:32 PM
How can I know the direction from which the sun light comes in this photo?

http://lc84.altervista.org/marte/imm...ake-2-edit.jpg (http://lc84.altervista.org/marte/immagini/mars-lake-2-edit.jpg)

Any help?

The light is coming from the lower-left corner of the photograph. Evidence: the lit-up and shadowed portions of the low ridges in the landscape outside the crater, the brightly lit rim on the right-hand side of the crater, the sunlit portion of the interior of the crater's wall on the right-hand side.

NEOWatcher
2007-Oct-02, 12:53 PM
The light is coming from the lower-left corner of the photograph....
The link worked for you?

I end up with the following address (like it's redirected) to http://images.altervista.org/images/void.gif

a1call
2007-Oct-02, 01:23 PM
NEOWatcher,
It didn't for me, I right clicked > copy link location and pasted in address bar and now it works.

jumpjack,
Wonderful image. Please post the link to the original image.

schlaugh
2007-Oct-02, 01:54 PM
jumpjack,
Wonderful image. Please post the link to the original image.

It's from the HIRES site...

http://hirise.lpl.arizona.edu/PSP_004847_1745

The image page also describes a fair bit about the image, sunlight angles, etc.

NEOWatcher
2007-Oct-02, 02:11 PM
NEOWatcher,
It didn't for me, I right clicked > copy link location and pasted in address bar and now it works.
Weird...it works both ways now...Maybe it was a temporary thing that I was unlucky enough to hit.

Thanks anyway (and to schlaugh too, for the extra link)

01101001
2007-Oct-02, 03:49 PM
Weird...it works both ways now...Maybe it was a temporary thing that I was unlucky enough to hit.

Consolation: you weren't the only one.

jumpjack
2007-Oct-03, 12:08 PM
Consolation: you weren't the only one.
It's not your fault, guys: simply, altervista server do not like direct links...
But, once yousuccessfully download the image (by pasting address in url bar), you'll be always able to see them.

Anyway, I DON'T wanto to determine sunlight direction FROM picture! I want to do exactly the opposite! I need sunlight direction in degree, to better understand the picture.

A guy from Planetary Data System suggested me to download file EDRCUMINDEX.TAB (http://hirise-pds.lpl.arizona.edu/PDS/INDEX/EDRCUMINDEX.TAB) from this folder (http://hirise-pds.lpl.arizona.edu/PDS/INDEX/), but it's HUGE (55 MB!), I didn't do it yet... Any volunteer? :whistle:

Download (http://hirise-pds.lpl.arizona.edu/PDS/INDEX/EDRINDEX.LBL)fields list for file EDRCUMINDEX.TAB.

Interested on other photos of mars holes? Take a look to my two articles (sorry, only italian):
http://lc84.altervista.org/marte/buchi marte.html (About first image, lots of links)
http://lc84.altervista.org/marte/buchi-marte-2.html (about updated image)

[edited wrong links]

jumpjack
2007-Oct-05, 12:54 PM
I downloaded the full data file; this is an excerpt, containing just data about the two "mars holes" images:
http://www.planetmobile.it/jumpjack/buchi-marte-dati-completi.txt

Can anybody help me determining the exact direction of sunlight in degrees? I'm really confused by "sub_solar_longitude" and "sub_solar_azimuth" parameters, which appear not to be matching with the "local_time" parameter.

Where the he** was the sun?!? Left or right of the hole??? :mad: