[UW-GIS-L] Best projection for measuring distances across theWestern Hemisphere?

[Phil Hurvitz]

Hi Tristan, you might consider PostGIS, which supposedly calculates 
great circle distances. This is a good synopsis:

http://workshops.opengeo.org/postgis-intro/geography.html

-P.

**************************************************************
     Phil Hurvitz, MFR | PhD Student, Urban Planning | CBE
         1107 NE 45th Street, Suite 535 | Box 354802
University of Washington, Seattle, Washington  98195-4802, USA
phurvitz at u.washington.edu | http://gis.washington.edu/phurvitz
"What is essential is invisible to the eye." -de Saint-Exupéry
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On 10/21/2010 10:55 PM, Jin-Kyu Jung wrote:

> I think It should be one of equal-distance projections. In ArcGIS, Azimuthal Equidistant, Equidistant Conic or Equidistant Cylindrical can be a good option. I am a little bit surprised that ESRI help site suggested conformal, equal area (e.g. sinusoidal) or even compromised Robinson projection to measure an accurate distance, though. Please, someone correct me if I am wrong. Thank you!

>

> Jin-Kyu Jung

>

> On Oct 21, 2010, at 10:30 PM, Keven Bennett wrote:

>

>> World Robinson is the best I know of.

>>

>> Keven

>>

>> -----Original Message-----

>> From: uw-gis-l-bounces at mailman1.u.washington.edu

>> [mailto:uw-gis-l-bounces at mailman1.u.washington.edu] On Behalf Of Tristan

>> Nunez

>> Sent: Thursday, October 21, 2010 8:58 PM

>> To: uw-gis-l at u.washington.edu

>> Subject: [UW-GIS-L] Best projection for measuring distances across

>> theWestern Hemisphere?

>>

>> Hi GIS folks,

>>

>> Do you have any suggestions on the best projection to use to measure

>> distances in km (using the Euclidean distance tool in Arc 9.3) ranging

>> from 0 km to 1000 km, across the Western Hemisphere? The map is

>> currently in GCS_WGS_1984.

>>

>> Sources on the web and in ESRI's help site suggest that the Bipolar

>> Oblique Conformal Conic projection was useful for this purpose, but

>> ArcMap 9.3 doesn't have it in its coordinate systems library. From the

>> ArcMap 9.3 help files, it seems like a sinusoidal projection centered

>> at 90 W, a Robinson projection, or doing North and South America

>> separately in a Lambert Conformal Conic projection would be the best

>> compromise.

>>

>> Any thoughts would be highly welcome.

>>

>> Many thanks,

>>

>> Tristan

>>

>> --

>> Tristan Nuñez

>> Master of Science Candidate

>> Landscape Ecology and Conservation Lab

>> University of Washington

>> tristan.nunez at gmail.com

>> c. 503-819-5884

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