Mars Image: Person standing on cliff?

I want to demonstrate how slope and surface irregularities interact with shadows from objects. I made a simple irregular valley shape to imitate the terrain in the photo. I added objects at various points on the slope and one on a flat portion of the surface. The objects are cubes with rounded corners and are of equal height, depth and width.

I used the information from Internos to match the sun angle with the camera looking down as in the satellite image.

Notice the varying lengths of the shadows, depending on slope, as well as the irregularities in shape. The object on the bottom right is sitting on a flat regular surface as a control.

Even though these are basically cubes, they produce very long shadows with the sun at the same angle as the satellite photo's and while sitting on a slope.

I did this so people could better understand shadows and what they do or don't mean about the shape of the object. The object in question is likely sitting on a steep slope and is probably not much taller than it is wide or deep. In other words a rock or outcrop.




[edit on 6/27/2008 by Blaine91555]

Thanks, Internos, for pointing my this thread, although I think I do not have much more to add.

Originally posted by Chonx
Also, whats the scale on this picture, do you know? Might give us a clue as to how big this thing is.

At 52.2 cm/pixel, as this is more or less 20 x 16 pixels when seen at 100% zoom, it has a size of something like 10 x 8 metres.

Originally posted by babylonstew
i think i read somewhere the cameras have a resolution of 12m per pixel and 120m per pixel or something liek that?

The resolution depends on the distance to the ground, when closer to the ground the resolution is around 25 cm/pixel, when farther away from Mars (it does not have a circular orbit) the resolution drops to around 50 cm/pixel, as in this case.

Originally posted by AGENT_T
Nothing else seems to be casting much in the way of a shadow except this.

Everything is casting shadows in the same direction, look with more attention and you will see it.

Also, if you look around you will see more things like that (rocks?) casting shadows in the same direction.

Originally posted by schrodingers dog
And the shape of the shadow is one of something really thin and tall that is not consistent with the rest of the landscape.

The shape of the shadow only shows the width of the object, the height can not be known, even if we know the angle between the sunlight and the horizon (the measurement Internos posted, 19º), because we do not know the angle between the ground and the horizon, a shadow projected on a wall is not the same as a shadow projected on a downslope.

Originally posted by saturnus1962
The "shade" is pointing the wrong direction! Look at the other things, the light is clearly coming from the northwest side of the picture. The "shade" of the object is pointing the same way!

The shadow has the right direction, I wonder why you don't see that.

Look to all the smaller rocks on the image Internos posted, all the shadows point to the same direction, and they all are consistent with the Sub-solar azimuth value, 48.5º

(A 48.5º Sub-solar azimuth angle means that the angle, clockwise, between a reference line from the centre of the photo to the right edge of the photo and perpendicular to the right edge is 48.5 º.
It would be something like this:


)

Anyone really interested in this (or in any other photo) should work with the best version available, and in this case that is this image, a 234.0 MB JPEG2000 file, compressed without loss of detail.

The next best thing is using the quicklook version, a smaller (118.2 MB) JPEG2000 file with very little loss of detail, or use the IASViewer version, that can be streamed online just to show the area with are looking at without downloading the whole image.

IASViewer is available here.

[edit on 27/6/2008 by ArMaP]

reply to post by Blaine91555


Excellent post, I have seen so many people forgetting that the shadows are not always projected on flat, vertical or horizontal, planes that it makes me wonder if those people see anything around themselves during all their lives.

Not sure if this been asked.. but why are the craters being illuminated from the sun which if we take the upper page as north, the sun is NNW.. while the shadow in question looks like its being illuminated SSE?

reply to post by Willbert


Why do you say that the Sun comes from what would be NNW (if the photo had the North at the top, which is not the case)?

To me its clear that the Sun comes from the bottom right corner, as I pointed in the image I posted, and that is consistent with the shadows and the illuminated areas.

And what craters are you talking about?

Very thoughtful work. Flagged.

Many times you have to stand back and really think. At first glance these objects are out of place, yet the shadows make it quite odd. The slope theory is a good sound explanation, but the surface reflective being so different from the regolith is still mysterious.

I used to see many strange and out-of-place geology such as this when in my Earth exploring years. I used to do weeks in wilderness in Death Valley where without forests gives you incredible views of geology in motion. Sometimes a much different type of rock is exposed as the surface is eroded away. Could be rock at a lower level just being exposed. I don't think this is that however.

There are no impact remnants from these rocks being thrown to position, but could be from impact ejecta millions of years ago and now being exposed by erosion. A second image of the area with alternate lighting or detail might give us some insight.

Quite worth our invest of thought I think. Bound to learn something.

GMM

marsrovers.nasa.gov... I expect other angles will bring this face into clearer view. Look for the backwards NUMBER 4 shadow as reference to the location of faces.

reply to post by vze2xjjk


Are you sure these images are for this thread?

They have nothing to do with the image from the opening post (the only thing in common is that they are both from Mars).

It is interesting that the object does not appear in previous images of the same spot. Nasa is getting sloppy, likely due to cut backs they are struggling to keep up with demand in the airbrushing facilities.

At the risk of going off topic, I would like to ask those who are so obsessed by faces in the OP's pics what they think about this one:




Obviously, faces are not particularly difficult to find no matter where you look....even pizza is suspect. Of course mars has faces, your mind is very adept at finding them.

That being said, I do believe that the Cydonia face will one day be proven to be an anomalous formation, as far as the rest of the 'rock speculations', they are likely to be a product of the mind...either that, or the same forces that shaped mars are at work on earth shaping pan pizzas worldwide....

reply to post by SystemiK


Not only you spotted an alien into a pizza, it is even a well known one :


Lol, i swear that im not drunk, but i see it clearly

reply to post by Loke.


There are those things with a round white ball on top again! I pointed out on another thread, one of these, in a completely different location, and to me this looks like the same thing I saw there, only longer. Cool.

Originally posted by internos
reply to post by SystemiK

 

Not only you spotted an alien into a pizza, it is even a well known one :

Lol, i swear that im not drunk, but i see it clearly

Oh man, this had me laughing my ass off.

close up pics wtf lol

reply to post by Anonymous ATS


100% zoom and "auto Dynamic Range Adjustment" in IAS Viewer, wtfed and loled back to you.

reply to post by Willbert


I agree!!!! I have posted it on the second page as well, but no answer, i don't get it how the shade can go 2 (opposite!) directions.

It is unmistakeble the sun is coming from the same directions as the shade point; conclusion: no shade but rather a trail....

I can not see the sun coming from the direction that most of the posters think, an (official) statement on that?

reply to post by saturnus1962


Well, I have asked more than once why people think that the Sun is coming from the top left of the picture, because the Sun is coming from the lower right corner, as I pointed in this post and is visible in every place of the picture that has shadows, but nobody explained why they think that the Sun is coming from the top left.

reply to post by ArMaP


Sorry to respond so late, I am in a different time-zone and I had exams Yesterday. My point is that the ridges, clifs, hilss or what ever you like to call them have "suncast" from the north. I agree with you that the objects which are clearly to see in Internos post. Have opposite "shades", because that is impossible, i like to hold to the northside of the sun because of the hills, etc. I hold the other shades as trails as after you have thrown a hand full of pebbles in to the sand into one directions.

Just my 2 cnts

reply to post by jenny52


I can upload my images now - found 4 altogether. The 'heads' and 'people' on the cliff top are most likely tricks of light and shade but I find the 'tunnel entrance intriguing.



I hope the link is correct - it's my first time.

It seems they will only let me have one of the images but this is the one that I find intriguing.