The information connecting numerical coordinates to actual locations on the earth.
35
votes
7answers
2k views
What strategies, criteria, or rules to use for selecting coordinate systems?
What strategies, criteria, or rules do you use for selecting coordinate systems for
(a) storing,
(b) analyzing, and
(c) displaying GIS data?
(I humbly offer my reply to a related question ...
89
votes
8answers
16k views
What's the difference between a projection and a datum?
What's the difference between a projection and a datum?
14
votes
1answer
493 views
How accurate is approximating the Earth as sphere?
What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them.
Are ...
17
votes
1answer
2k views
Is WGS84 itself a Coordinate Reference System?
I was wondering the difference between WGS84 and EPSG:4326 (see this).
Can then WGS84 on its own be defined as a Coordinate Reference System?
Or is it just a datum so that a Coordinate System must ...
5
votes
1answer
406 views
How to reproject a raster file in QGIS with datum transformation?
I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
4
votes
1answer
622 views
Determine the UTM zone/hemisphere in a particular datum
I'm using GDAL to convert coordinates from one system (geographic or projected) to another.
Assume I want to convert geographic coordinates (latitude and longitude) in the WGS84 datum, to UTM ...
4
votes
2answers
3k views
Basic proj4 conversion UTM grid -> longlat and back
I'm a GIS novice, and am struggling to understand how to drive proj4 to accomplish what seems like a simple thing. I've googled for a couple of days, but everything I find seems to presuppose quite ...
3
votes
2answers
449 views
Vertical Datum Conversion Utilities
I have some data (points and rasters) that I would like to be able to convert to and from several vertical datums, including MLLW in coastal Florida. I would appreciate it if people could provide some ...
2
votes
2answers
61 views
Where can I get the list of Geographic Tranformations in ArcGIS and the area where they are aplicable?
I have some data in Provisional South American Datum 1956, and I need to project it to Web Mercator with WGS84 as the datum.
When I use the project tool in ArcGIS desktop, it requires a Geographic ...
0
votes
2answers
2k views
Converting from British National Grid (27700) to WGS84 (4326) to Web Mercator (102100)
I'm developing a web application that uses ESRI ArcGIS to display a map using JavaScript.
We are holding all our data in MS SQL Server 2008 as Easting/Northing against the British National Grid. ...
