Tom - Mars Reconnaissance Orbiter question

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18 years 7 months ago #10445 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rderosa</i>
<br />Assuming this type of situation, would the feature be seen clearly from the MRO camera?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, the camera resolution is much better than that of a human eye. But if the feature is too big, MRO might only take in part of it at a time. It would have to assemble the whole image as a mosaic. -|Tom|-

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18 years 7 months ago #10446 by rderosa
Replied by rderosa on topic Reply from Richard DeRosa

<i>Originally posted by tvanflandern</i>
Yes, the camera resolution is much better than that of a human eye. But if the feature is too big, MRO might only take in part of it at a time. It would have to assemble the whole image as a mosaic. -|Tom|-

Tom,

Is it possible for the resolution to be "too good" to see the feature in my example. In other words, can you see a scenario where the high resolution camera resovles so much detail as to obscure the feature in question? Sort of like my analogy of looking at the Mona Lisa through a microscope?

rd

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18 years 7 months ago #17261 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rderosa</i>
<br />Is it possible for the resolution to be "too good" to see the feature in my example.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No. You can always reduce resolution. -|Tom|-

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18 years 7 months ago #10447 by rderosa
Replied by rderosa on topic Reply from Richard DeRosa

<i>Originally posted by tvanflandern</i>

No. You can always reduce resolution. -|Tom|-

Hmmmm. Either I'm way out in left field on this one, or I'm not able to communicate what I'm getting at. Let me see if I can approach it from a different point of view.

Suppose an ancient civilization was capable of "drawing" or "etching" images or artwork in the planet's surface. Also, suppose they did it from very far away, and their resolution was very large, because it was intended to be seen from far away, or from some unknown distance. Maybe they discolored boulders the size apartment buildings, separated by no markings the size of city blocks. So, viewed from these vast distances, the images could be seen clearly. Maybe people saw, eyes, nose, mouths, groups of people,a city block etc. But then, we come along and get a glimpse of one of these things, but it's faint and blurry.

Ok, then we say, "we have to get closer look at this". So we use our normal approach and get higher resolution images thinking where going to "fill in the blanks" and see the whites of their eyes, the blouse they're wearing, windows in the building, etc. But when we take these high res images all we see between the discolored boulders that this ancient civilization rendered with lasers the size of the boulders, is the natural terrain, and we conclude "natural origins". In other words, increasing the resolution makes it harder to see the original intent of the artists, not easier.

Can you see any possibility of that at all?


rd

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18 years 7 months ago #10448 by Larry Burford
Here is my take on an answer to your question.

Some images are made of dots (like wire photos in news papers, or text on a monitor). If you get too close, all you see is dots, but from the minimum distance or greater the dots merge into a "smooth" image.

Suppose such an image was taken of an object that was only as large as a dozen or so dots. You would not be able to see any real detail, but you could see that there was definitely something to see. Your first inclination would be to enlarge the image to see the object better. But becaues of the way the image is built that would not work. You would only get dots.

===

An object that was originally smooth (such as a very large sculpture of a humanoid face) might come to resemble an object that was "dotty" if pieces of it were removed (for example by random bombardment with many small objects over a long period of time).

In such a situation the best you could do is observe the object from a distance that shows it as if it were a small number of merged dots. Much like your example feature that can be seen from 50 km altitude, but not more and not less.

I sure hope we don't find ourselves in such a situation ...

LB



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18 years 7 months ago #10449 by rderosa
Replied by rderosa on topic Reply from Richard DeRosa

<i>Originally posted by Larry Burford</i>

It is a safe bet that everything within 10 kilometers of the surface will be in focus.

Larry,

Is it that everything within "10 km of the surface will be in focus" or everything beyond 10 km of the camera all the way to the planet's surface will be in focus? Huge difference. Remember, in my original question I asked if a small craft hovering 50 km above the planet's surface would also be in focus at the same time as the planet's surface. I think Tom's answer tells me it's the latter.



rd

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