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Martian Cartography
karolp
post May 15 2006, 04:16 PM
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I have recently freaked out a little bit about Martian maps of all sorts. And finally I was astonished with those highly detailed beauties that I list below. Nonetheless. some of them have huge inconsistencies (crater names) easily noticed when we compare the surroundings of Gusev crater. Enjoy:

http://www.ralphaeschliman.com/
http://planetologia.elte.hu/1cikkeke.phtml...arsmapinte.html
http://pubs.usgs.gov/imap/i2782/


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Guest_PhilCo126_*
post May 21 2006, 03:26 PM
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http://marsoweb.nas.nasa.gov/dataViz/
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Phil Stooke
post May 21 2006, 04:21 PM
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karolp, I have looked at these maps, and I don't see any real discrepancy with the names - I only checked around the Gusev area, since you mentioned it.

The apparent difference is caused by the fact that these maps only use a selectuion of all available names. Each map has a slightly different selection. For instance, the multilingual map from Hungary does not include the name 'de Vaucouleurs'. You need larger scale maps to include all the names which have been assigned to Mars. The USGS set at 1:5,000,000 is a good start, but of course there is the problem of updating.

Phil


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Guest_DonPMitchell_*
post May 22 2006, 05:35 PM
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I like the second USGS map.

[attachment=5804:attachment]

Nice hill shading, nice subtle colors, not the usual fully-saturated acid-trip color schemes you see in a lot of NASA images. My one criticism is that the hypsometric color pallette should go from dark to light monotonically with altitude. It's a little confusing that you go from light brown to dark brown and back to light brown again as you head up the Tharsis rise. Things to keep in mind when making your own maps.

Here are two wonderful sites about map making, full of good ideas and wise advice:

The National Park Service: Shaded Relief

History and techniques: Relief Shading. Explore this site, check out the section on Cartographers and examples of their work. What a fascinating art.

For example, look at this amazing projection of a map of Europe designed by Heinrich Berann:

[attachment=5805:attachment]


(By the way, to yank pictures out of the annoying pdf files, you can use PDFExtractTiff by verypdf.com)
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chuckclark
post Nov 23 2007, 06:58 PM
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Here are two constant-scale natural boundary maps of Mars showing color topography.
CSNB maps are made by a geometrical method of my own devising. These of Mars were suggested by Rene de Hon at the 2003 ISPRS meeting in Houston.

The "Mars as a dale" CSNB map has as its edge the primary ridges of the southern highlands. It's the view from the top down, so to speak, from the edge of the map inward.

The Mars as a hill" CSNB map has as its edge the primary valley-lines of the northern lowlands. It's the view from the bottom up, relative to the edge of the map inward.

The dividing line of the crustal dichotomy thus occurs as a ring around the middle of each map.

The maps or as twins, mirrored points of view.

The accompanying cylindrical insets show the boundaries of the respective CSNB maps.

Cheers
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Guest_PhilCo126_*
post Nov 23 2007, 07:34 PM
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About three years ago, I've written an article on mapping the planet Mars and its Moons (with cylindrical projections of Phobos and Deimos provided by Philip Stooke wink.gif ), more specifically about producing 3D models of the planet (4 foot diameter globes) and the Moons (made by Ralph Turner). E-mail me if You wont those articles in .pdf format...
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Phil Stooke
post Jan 9 2009, 08:59 PM
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here's an interesting comparison if anyone's interested. It's a comparison of global cylindrical (that is, simple cylindrical, or equirectangular) projection maps of Mars from Mariner 9, Viking and MGS. The Mariner 9 one is the 1975 USGS map, reprojected into Simple Cylindrical. Viking is the global mosaic made by USGS. MGS is a composite of TES albedo mapping and the MOC wide angle geodesy mosaic, both with artifacts removed. Some problems remain in all of them, but you do get to see significant changes in the pattern of albedo markings. We tend to forget about them now, being so focussed on boulders and layering. It would be possible to make maps like these for every opposition since about 1840 - that would make an amazing animation!

Phil

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dvandorn
post Jan 10 2009, 05:22 AM
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Great comparison presentation, Phil. Very easy to compare the albedo features mapped by each team.

I do want to point out that the Mariner 9 map was prepared with far greater contrast than the other two maps, which attempt to present realistic-to-the-eye contrast levels. So it's easier to compare features between the Viking and MGS maps. Variations between the Mariner 9 map and the other two maps seem just as likely to be artifacts of the preparation as they are actual changes over time.

Also, I think it bears mentioning that Viking and MGS overflew the terrain at different times of day nadir LST. IIRC, MGS flew over terrain which, at nadir, was at roughly 2pm LST, and I believe Viking had a couple of different windows (with the two different orbiters) but saw nadir at generally lower sun angles (I want to say between 3 and 4 pm LST, but I just can't remember with confidence... *sigh*... ).

We all know albedo features can vary somewhat by sun angle, so at least some of the variations between the Viking and MGS maps may be due to different sun angles.

However, all of that said, there are obviously places where large gross changes (and also small, subtle changes) have occurred in the times between the three eras. And that is very definitely fascinating. Plus, I seem to recall that some people already have done analyses of albedo variations in telescopic images/drawings from oppositions since, oh, probably 1840.... smile.gif

In fact, I remember reading a book when I was a kid that presented Mars images from several successive oppositions, comparing the albedo features and noting observed changes. It might make a good thesis for some astrogeology postgrad out there to pull up all those old telescopic analyses and plug them into the patterns of changes we've seen from our orbiters from 1971 to present... wink.gif

-the other Doug


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Phil Stooke
post Jan 10 2009, 01:08 PM
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Very true, Doug. The top image was produced in a very different way. While the other two are spacecraft data, albeit manipulated, the top one is a drawing. It exaggerates small details more than the other two, and is more contrasty. My intention is to show surface changes, and it does do that well - look around Isidis and Elysium, or north of Tharsis, especially.

Actually I had another reason for making these. I'm preparing a set of maps to serve as base maps for my Mars atlas. As I go through the history of Mars exploration the base map I use will evolve to follow the growth of our knowledge, and then the changing appearance of the planet. Step 1 is the old ACIC map, pre-Mariner 4, with canals. They have to be converted to Simple Cylindrical so my software can reproject them into the azimuthal projection I will actually use in the book.

Phil


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tedstryk
post Jan 10 2009, 01:38 PM
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I have a set going back to I think the 1890s...If I can find it I will post it (that is a big if).

Ted


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AndyG
post Jan 11 2009, 11:36 AM
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Hi Don,

Mapping is an ancient art, and I'm a great fan of relief shading (my Dad's ancient cloth map of the UK's Lake District is a joy to behold). It's a shame that the technique's fallen out of popularity.

AndyG
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Phil Stooke
post Jan 15 2009, 08:53 PM
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Speaking of ancient art... here's a map of Mars made from the Mariner 6 far encounter images.

Phil

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Phil Stooke
post Jan 21 2009, 09:15 PM
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... and here's Mars seen by Mariner 7, far encounter only. It took a better set of images than Mariner 6. Next step - add the near encounter frames.

Phil

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elakdawalla
post Jan 21 2009, 10:14 PM
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Very cool. Mars comes in to focus. Thanks for posting these.

Does the shape of Mars and the variety of mapping conventions that have been used over the years cause problems with geographic features appearing to shift from one mission to the next? (Obviously, it's not the geographic features shifting, just the coordinate systems we use to represent them...)

--Emily


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Phil Stooke
post Jan 21 2009, 11:28 PM
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Not really - shifts between these mariner maps, and between them and the later maps I posted, are partly caused by registration errors (mariner 7 here is more carefully done than mariner 6 was), and partly by albedo boundary shifts - Syrtis Major especially has changed a lot.

Phil


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