Re: [postgis-users] Distances off in the Southern US

2011-08-15 Thread Mike Hostetler
I'll try to answer everyone's suggestions: I didn't know that Yahoo's service was in 4326. That did change things up a bit. And, yes, I did copy the value from Birmingham to Miami twice. Sorry about that. . . My customer was comparing my results to a different source but it seems close to Googl

Re: [postgis-users] Distances off in the Southern US

2011-08-15 Thread Paul Ramsey
You're using polar stereograpic as your projection? http://nsidc.org/data/atlas/epsg_32661.html Well, yes, the farther south you go, the more over-determined your distance will be. Use the geography type, as suggested below, or the st_distance_spheroid() function, or just use a projection that i

Re: [postgis-users] Distances off in the Southern US

2011-08-15 Thread Dan Putler
Hi Mike and Nicolas, The fact that Mike's two calculations resulted in the same value to 12 decimal places is more that a little fishy. I seem to remember a similar issue coming up on this list sometime ago (roughly a year ago is my, faulty, memory). The difference between southern and norther

Re: [postgis-users] Distances off in the Southern US

2011-08-15 Thread Nicolas Ribot
On 15 August 2011 12:50, Mike Hostetler wrote: > Hello, > I'm somewhat new to GIS and I have a problem that I thought appeared to be > simply using a wrong projection or datum, but it seems to be a bit more > subtle than that. > I have a table of cities in the US and I'm trying to find distances b

[postgis-users] Distances off in the Southern US

2011-08-15 Thread Mike Hostetler
Hello, I'm somewhat new to GIS and I have a problem that I thought appeared to be simply using a wrong projection or datum, but it seems to be a bit more subtle than that. I have a table of cities in the US and I'm trying to find distances between them. When I use a city that is in the northern U