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Distant vistas, Endeavour, Iazu, and beyond
pgrindrod
post Feb 3 2010, 02:04 PM
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QUOTE (djellison @ Feb 3 2010, 10:42 AM) *
Pete - chuck that Pathfinder demo of Viewshed in here as well ( I never got around to using it) - it demonstrates the power of the technique.


Yes boss! I'll stick it over in the HiRISE DEM thread.

Pete
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ngunn
post Feb 3 2010, 02:40 PM
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There are just great. Any chance you could extend the area S and SW to check out the potential visibility of Bopulu and 'south hill' from a little south of our present position?
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ElkGroveDan
post Feb 3 2010, 02:53 PM
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Did we all notice that the SW flank of Victoria should still be visible? ( with deference to the pinch of salt and all that)


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ElkGroveDan
post Feb 3 2010, 02:57 PM
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QUOTE (ngunn @ Feb 3 2010, 06:40 AM) *
Any chance you could extend the area S and SW to check out the potential visibility of Bopulu and 'south hill' from a little south of our present position?

If we were really greedy we would ask them to animate the sequence down the drive path so we'd see green features growing and shrinking in the view from above with an in-set image showing a red dot moving down the drive path. But that would take a lot of time and all we have to offer is boundless admiration and praise. wink.gif


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fredk
post Feb 3 2010, 06:50 PM
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QUOTE (pgrindrod @ Feb 3 2010, 11:00 AM) *
I've had a go at predicting what Opportunity can possibly see

This is really cool, Pete. I've got a couple of questions/comments. First, does this take into account the curvature of the surface?

Your results definitely look sensible along the inside of the far rim of Endeavour, presumably since the slope is quite large there. But in both plots, there are areas right adjacent to the observation point that aren't green. Why is that? I can see that the blotchiness of the green areas on the flatter areas makes sense, since the slopes there are extremely small. But it should still be green close to the observation point.

I see what you mean by the green areas changing quite a bit when you move the observation point around - again, since the terrain is so flat. I wonder if you could do a series of these plots, each time moving the obs. point around a bit (say within a 10 metre or even 100 metre region), and then take the union of all the green areas. That may eliminate the high frequency noise.
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pgrindrod
post Feb 3 2010, 07:40 PM
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Yeah I'm troubled by the lack of visibility around the marker point too. My gut feeling is that this is all coming down to the underlying HRSC DEM, which is 75 m/px. This is probably too coarse to do a viewshed at the scale that we're interested in. But I've got to admit that this is the first real time that I've played around with this method so I'm still learning the ins and outs. Now if someone had a CTX DEM of round here... smile.gif

So I'm going to have a bit of a play around and see how things change as the marker moves around. I've got a feeling that I might be 'overinterpreting the data' as they say (ie making it up!). But the idea of moving around and averaging is interesting, and if I come up with anything then I'll put it up. I might even try a little bit of MOLA as well, see if that improves things, as that's what Tim Parker's LPSC contour map used I think.

Pete
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Phil Stooke
post Feb 5 2010, 02:57 AM
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Here's an extreme vertical stretch of the hills with a bit of noise reduction from adding frames where possible.

Phil

Attached Image


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ngunn
post Feb 6 2010, 09:31 AM
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Something dark on the skyline in this view, though likely not at extreme distance. Is there another small crater in that direction?
http://qt.exploratorium.edu/mars/opportuni...66P2368L7M1.JPG
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Tesheiner
post Feb 6 2010, 12:37 PM
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Good catch, ngunn!
The heading is consistent with the next crater on the planned route. Here's it on Google Earth.
Attached Image
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Stu
post Feb 6 2010, 01:04 PM
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Wow, we've only just got here and we can already see where we're going next!

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Stu
post Feb 6 2010, 01:21 PM
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Concepcion and the Next Crater, seen at same scale, with the IAS viewer...

Attached Image


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ustrax
post Feb 6 2010, 04:03 PM
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QUOTE (Stu @ Feb 6 2010, 01:21 PM) *
Concepcion and the Next Crater, seen at same scale, with the IAS viewer...


Can't resist...stop me please... rolleyes.gif
I hereby name you...Double Dare! Aliki & Margot... smile.gif


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Nirgal
post Feb 6 2010, 04:22 PM
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As long as there is no HiRISE DEM yet ... here is a quick try at creating a single-image-DEM from the CTX image T01_000873_1780_XI_02S005W.
(with the whole DEM consisting of about 10 million polygons which is currently about the limit that my software's core math solvers can handle. So the next project I'm working on is to port and compile my sources into a true 64-bit application such that it can make use of the full 12 GB main memory under Vista 64 (I know, I know I should use a Mac, really wink.gif -> so maybe in the near future it will be able to generate DEMs with 50-100 million polygons.

some oblique views of the area between Victoria and Endeavour:

Attached Image

Attached Image

Attached Image


And the last image is how it might look like from the ground. However, I did not select a special viewing direction ... just played around with the camera position and rotation until it looked good ... ah yes, and the vertical height is somewhat exaggerated too wink.gif

Attached Image

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Tman
post Feb 6 2010, 04:40 PM
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Just at that twin crater we might get a better view to the south(west), i.e a sign of Bopulu crater and the hills eastward of its "promontory".

Oh my, very nice...good stuff, Nirgal! smile.gif


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fredk
post Feb 6 2010, 06:10 PM
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QUOTE (Tesheiner @ Feb 6 2010, 01:37 PM) *
The heading is consistent with the next crater on the planned route.

Early in this thread I suggested based on the navcams that this feature to the south was the hill far to the south. I agree it looks much too close to be that hill, which is farther than Iazu. But I'm not sure about your identification, Tesheiner. I'll call the close pair of craters you suggested Twin Craters (I guess they're not identical twins!). Measuring the angles each component (A and B ) would subtend at Conception, I find the Twins should look this big:
Attached Image

In other words, much bigger than the dark feature on the horizon. But looking closely, there are some dark features (black arrows) that could perhaps be one or both of Twin Craters somewhat closer than the horizon. In L2, these features look bright, which might be exposed bedrock on the rims?

Is there another feature somewhat farther than Twin Craters that the dark feature on the horizon could be?
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