OpenStreetMap
For starters, everything, and I do mean *everything*, is maybe 500 meters misaligned from the satellite photo. :(
Then we're missing a bunch of recently added roads - although there are at least some good GPS traces.
And then there are some lines that basically look like someone scribbled roads on the map, and the editor doesn't want to show me its "help" page in Firefox, so I can't figure out how to delete them.
Thankfully, it's a finite space; the island is smaller than Connecticut (if only just barely) and sparsely populated, so with a little dedication and a lot of free time (and maybe some others here working on it) we could have a top-notch dataset.
But for now? Ugh!
Diskuse
Komentář od lyx z 24. 01. 2009 v 08:50
Well, if *everything* is misaligned from the satellite photo then the satellite photo is probably misaligned. Try to get good GPS data of some locations that are clearly visible on the photo and use them to correct the image position.
Komentář od davidearl z 24. 01. 2009 v 12:52
If you're using Landsat, then yes, the images are misaligned in JOSM. The amount varies from place to place, though 500m is quite a lot. There is a button specifically to correct them.
Komentář od birchall z 24. 01. 2009 v 13:50
Thanks for the comments!
I'm using Potlatch, not JOSM (I suppose I should get JOSM now), and the misalignment is between the overlaid street map and the underlying displayed Yahoo satellite imagery.
I did, however, overstate the misalignment by a bit; I checked using gmap-pedometer and the straight-line misalignment of my home address is only about 445 meters, not 500. Still, an entirely different neighborhood of town, and of course we're coastal so some other neighborhoods show up as being in the ocean... ;)
Komentář od birchall z 24. 01. 2009 v 14:08
Oh, I forgot, in "view" the underlying grey terrain/blue ocean is also misaligned with the street map.
Komentář od birchall z 24. 01. 2009 v 14:18
I got JOSM, grabbed my local area including a GPS track from someone. The GPS track conveniently goes out on a peninsula and "stays within the lines" of the underlying coastline; the road map doesn't.
davidearl, I'm obviously a newbie and don't see a button to correct this - can you point me to it? :)
Komentář od es_ka z 24. 01. 2009 v 15:52
Dan, do you have "wmsplugin" in JOSM enabled? Then you will find a button with dark green background and four little white arrows on the left side of JOSM. Just put your mouse pointer over the button it the tooltip says "adjust position of WMS layer".
BTW, welcome onboard and happy mapping!
Komentář od robx z 25. 01. 2009 v 07:37
The scribbled lines might have to do with the TIGER import? Maybe you could post a link to the relevant area?
By the way, it is quite possible that the data is indeed misaligned. Especially if the GPS track supports this.