> ----- Original Message ----- > From: "Randy George" <[email protected]> > To: <[email protected]> > Sent: Thursday, April 02, 2009 3:49 PM > Subject: Re: [OSM-newbies] projection question in Hawaii > > > > Hi, > > Perhaps the island is offset. This test case lets me show OSM over > VE: http://www.web-demographics.com:8087/ The offset appears consistent > around the Island. Yahoo and VE align. Also the intersection locations > align > on Google Earth > > The cyan tracks in this test are from GPS: > http://www.web-demographics.com/Exacter/test.html and you can use the > infor > check map click to get the GPS record behind any of the points. > > The offset seems consistent around the coast. > dx= -0.002608 > dy = 0.003020 > > randy >
>From when I worked on the improving the coastline data around Hawaii I got the impression that the TIGER import was offset from reality. http://wiki.openstreetmap.org/wiki/TIGER_fixup#Accuracy:_Offset_from_reality However not being based on HI I had no way of confirming this with actual GPS measurements. Your track data seems to confirm the offset, and I would suggest that all data imported from TIGER needs shifting. I'm not aware of an easy method of achieving this shift however. A similar problem existed on Guam, and I advised that importing the island into JOSM and dragging all the data would allow the correction, but I think that for HI the size of the data might swamp JOSM. David > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of swanilli > Sent: Wednesday, April 01, 2009 6:49 PM > To: [email protected] > Subject: Re: [OSM-newbies] projection question in Hawaii > > Maybe this is evidence of a wider problem with Pacific Islands that > are close to the International Dateline. > > I have noticed that the location for the country tags for both Fiji > and Tonga are a long way from their true location. > > For Fiji the country is located on OSM at > http://www.openstreetmap.org/?lat=-28.08334&lon=-179.99&zoom=15. This > is probably a typing error (someone hit tie 2 key instead of 1) and > probably was meant to be > http://www.openstreetmap.org/?lat=-18.08334&lon=-179.99&zoom=15 which > would put it in the middle of the Fiji group of islands). > > I would have fixed these errors except that I don't know how to move a > country. > > Any suggestions on how to fix this? > > > > 2009/4/2 Iván Sánchez Ortega <[email protected]>: >> El Miércoles, 1 de Abril de 2009, Randy George escribió: >>> I also checked against Google Earth by locating LL -155.136552, > 19.68534 >>> on OSM and on GE. GE shows this point at the road intersection of Akolea > Rd >>> and Kaumana Dr, while in OSM it's shifted off the road? >>> >>> I assume I am doing something irregular. Are the OSM tiles >>> sphericalmercator EPSG:900913? Or some other EPSG? >> >> Yeah, OSM uses 900913 for rendering. Internally (for editing) it uses >> unprojected WGS84 (AKA EPSG:4326). >> >> >> Maybe the OSM data for that zone is just wrong (badly surveyed, maybe?) > and >> needs to be fixed. Have you checked (with a GPS) that zone? >> >> >> Cheers, >> -- >> ---------------------------------- >> Iván Sánchez Ortega <[email protected]> >> >> Un ordenador no es un televisor ni un microondas, es una herramienta > compleja. >> _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
