Map Features Overlays on a Cylindrical Projection |
Map Features Overlays on a Cylindrical Projection |
Jan 28 2012, 07:25 PM
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#1
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Greetings,
Thought I'd mention I'm starting a mini-project to make map feature overlays for planets and satellites. These are set up on a cylindrical projection so they can be displayed with Science On A Sphere, Celestia, and the like. The key is that text for feature names has to be "pre-distorted" so it looks correct when viewed on a sphere. This is especially important at high latitudes. The overlays are for now in the form of transparent PNG images. So far I've started with Mars and Enceladus. The programming language is IDL, and the lat/lon info for the feature names is from the USGS Map-A-Planet Gazeteer. I'll try to post some results once they are a little better. Enceladus is a special case, since the map I had put together is in planetocentric coordinates, and the feature lat/lons are in planetographic. So a conversion of one or the other would need to be done. Steve -------------------- Steve [ my home page and planetary maps page ]
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Feb 9 2012, 09:20 PM
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#2
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
Someone should make a map with 0 Longitude going down the center instead of the equator. At least then we would have correct perspective on the tiger stripes.
-------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Feb 14 2012, 04:28 PM
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#3
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Hendric, yes that would be an interesting presentation, basically rotating the data 90 degrees around the X or Y axis when making the cylindrical projection. The labels should look OK if the map in post #10 is so transformed.
Meanwhile, the general intent with these feature maps is to view them with a program such as Celestia, so one can see the features and labels with a proper perspective hovering over the location of choice. In the case of Celestia the tiger stripes and labels have the correct perspective, though the well-known Celestia polar pinch effect shows up here. -------------------- Steve [ my home page and planetary maps page ]
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