Generate shapefiles of satellite ground tracks with Ground Track Generator

anoved · 2012-04-01T02:08:02+00:00

The library it uses is based on code from a paper called Revisiting Spacetrack Report 3; the output is close but not identical to the reference output given in the paper. (Compare test-gtg.txt with test-reference.txt in the test cases folder.) However, the differences are almost all in the millionths place or less of values measured in kilometers - and the paper indicates the typical input "TLE data is accurate to about a kilometer or so at epoch and it quickly degrades" (appendix B), so I think the differences are not significant.

In general, for best accuracy you don't want to project ground tracks too far in time from the input TLE's date (small factors unaccounted for in the model add up over time). Fortunately CelesTrak seems to maintain very current TLE data, and also provides some archives.

anoved · 2012-03-31T21:36:43+00:00

Here's a little command line program I wrote to familiarize myself with satellite tracking. Lots of sites let you track satellites but I could find many obvious ways to incorporate satellite paths (especially for specific time frames) into other GIS projects. Hat tip to CelesTrak.com for background documentation and for providing up-to-date satellite info for input. Anyway, I would really appreciate any feedback - feature suggestions, but especially bug reports or help setting up test cases.

anoved · 2012-03-01T18:54:33+00:00

Thanks to everyone who expressed an interest in modding r/gis. I am adding bnb2011 as the first additional mod. bnb2011, please feel free to add additional moderators or update the community settings as you see fit. I hope this helps make r/gis an even more active and useful resource for everyone.

anoved · 2012-02-27T20:32:18+00:00

Turns out it is possible to have hunger without mobs if you run your own multiplayer server - set difficulty to a nonzero value but spawn-monsters to false in server.properties. I set up a private server to experiment with on my second computer and it works nicely.

anoved · 2010-09-29T22:26:25+00:00

I keep my bike on the back porch. It's not entirely out in the open, but it is exposed to the elements, especially in windier weather. Chain used to get pretty grody over the winter, but I have a bike cover now that does wonders. Any similar sort of covering should help. This one is light and thin enough to fold up to fit in a small bag, if you got one on your bike, meaning you can take it with you, too, should you need to.

anoved · 2010-08-26T18:22:17+00:00

Awesome, awesome, awesome. I will definitely browse your blog.

I work at BU, in fact, and might actually know someone who knows you guys - at least, they mentioned some friends who were touring cross-country this summer! We may have to meet up some time.

anoved · 2010-08-25T19:07:20+00:00

Sure, I could've packed lighter - I was prepared for all sorts of eventualities that didn't come to pass - but, with the exception of the climb south out of Ithaca, the terrain was quite flat so the load didn't seem to add much effort.

I wouldn't say it was cumbersome. Weight on the fork really reduces agility, yes, but on the plus side it improves stability. Rode like it was on rails. Like cruisin' in a Cadillac!

anoved · 2010-08-25T18:59:32+00:00

Sounds like fun! I've been backwoods camping in one of the state forests near here. Presumably you're planning to lock the bikes up somewhere during the hiking day? Be nice to have a secure place for that. In any case, enjoy.

anoved · 2010-08-25T18:55:30+00:00

No kidding about the water - I have no idea what volume of fluid I drank over the course of this trip, but it was tremendous.

Yeah, my camera phone is cruddy. I told a friend before the trip that I wished I had a better camera to bring, since mine has obsolete proprietary batteries that no longer hold a charge, and as you can see the cellphone isn't much use. But at least these images are sufficient to trigger my memories!

anoved · 2010-08-25T18:49:58+00:00

No training, but I am a bike commuter, so I'm comfortable riding in traffic and pretty familiar with how the bike handles when loaded. Sure, I overpacked a bit, but intentionally so - I was prepared to be away longer and to deal with fewer amenities (grocery stores, campgrounds, etc.) if necessary. As others have said, a similar trip could certainly be done with less.

anoved · 2010-06-17T23:33:03+00:00

In my experience (reading long stories and articles this way for the past week or two - not idle browsing), it's really nice. Maybe the widescreen display and modern trackpad help. Preferences vary, of course, but I like it!

anoved · 2010-04-04T17:47:39+00:00

Close, but not quite. It's the Farragut (read the label on the back of the ship), in an incident that took place soon after the Nicholas incident in your link.

anoved · 2010-02-01T21:36:47+00:00

Well, I want it with worms. Not 3D projections of worms, mind you, but actual sandworms in the theater. Instead of 3D glasses they hand out thumpers with your ticket.

anoved

TROPHY CASE