A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions.

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18
votes
3answers
13k views

Layers with same coordinate system should align/overlap but do not?

I put 4 different layers into my ArcMap document, but only one of them will show up on the map! I should be seeing the other 3 layers as well. When I do a Zoom to layer, I can see one layer, but I ...
29
votes
11answers
8k views

Identifying Coordinate System of Shapefile when Unknown?

I have a Shapefile but its coordinate system is Unknown, and there is no *.prj file. How I can identify it now? Are there any tools that could help?
28
votes
3answers
29k views

Algorithm for offsetting a latitude/longitude by some amount of meters

I'm looking for an algorithm which when given a latitude and longitude pair and a vector translation in meters in Cartesian coordinates (x,y) would give me a new coordinate. Sort of like a reverse ...
42
votes
7answers
3k 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 ...
16
votes
5answers
19k views

Get list of coordinates for points in a layer?

I've got a layer in QGIS that is comprised of points. Its attribute table doesn't have (show) the corresponding x and y coordinates for each point. Is there a way for me to extract a list of ...
19
votes
1answer
1k views

What is most accurate coordinate system for calculating areas of polygons?

I have multiple polygons, all located offshore around the UK. I am trying to calculate the areas of these polygons in square kilometres, without splitting them by UTM zone. Is it possible to do this ...
4
votes
1answer
583 views

Raster incorrectly reprojected to OSGB(27700)

Ubuntu 12.04, QGIS 1.8.0, GDAL/OGR 1.7.3, GEOS 3.2.2 Open a Spatialite db with OS Mastermap poly layer (EPSG:27700); Add OpenLayers Plugin (1.0) from QGIS offical repository; Add a Google Satellite ...
34
votes
3answers
7k views

LatLon or LonLat, what's the “right” way to display coordinates and inputs?

I'm trying to get a sense if this is an issue for others or every input/output should be labeled so user is not confused and just go with it? I think almost everyone pronounces it as "LatLon". Who ...
9
votes
2answers
1k views

How can I convert geomagnetic coordinates to geographic coordinates without doing the math myself?

I have some data which are in geomagnetic coordinates; that is, they are latitude and longitude, but in reference to the magnetic north pole in Canada rather than the geographic north pole. As you ...
5
votes
2answers
691 views

Identify the latitudinal and longitudinal point directly beneath an object in space

Given the azimuth and altitude / latitude and longitude from the observer to the satellite, how can I accurately find the latitude and longitude of the point of intersection directly under the ...
19
votes
1answer
4k 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 ...
24
votes
3answers
19k views

What is the difference between WGS84 and EPSG4326?

What is the difference between WGS 84 and EPSG 4326? It seems like for a given dataset it might be both WGS 84 and EPSG 4326.
9
votes
2answers
1k views

Which function for creating a POINT in PostGIS?

When defining a Point in PostGIS, when do you decide to use which of the following? ST_SetSRID(ST_MakePoint(lon,lat),4326) ST_SetSRID(ST_Point(long,lat),4326) ST_SetSRID(ST_GeomFromText('POINT(lon ...
8
votes
1answer
1k views

How to compute the bounding box of multiple layers in lat/long?

I am writing an application to performance test all kinds of map services, primarily AGS 9.x, AGS 10, and WMS 1.x. Part of the application involves generating random bounding boxes for individual ...
6
votes
1answer
1k views

Difference between Geographic-3D and Geocentric CRS

I'll start with the OGP definitions: Geographic. A coordinate reference system based on a geodetic datum and using an ellipsoidal (including spherical) model of the Earth. This provides an accurate ...
3
votes
1answer
136 views

QGIS display does not reflect projection

I have slight experience with ArcGIS, but am new to QGIS. I'm trying to set the projection of my map, and I understand that this is done by altering the CRS (coordinate reference system) of each ...
8
votes
1answer
188 views

Using customized Coordinate System for Archaeological site data

I don't know so much about coordinate systems... In my office we use to deal with spatial data coming from archaeological sites. Each site has its own x-y-z coordinate system (GCS). Three simple ...
9
votes
3answers
5k views

How does ArcGIS compute the distance between two points with a non-equidistant projection?

This is a follow-up question to my previous one, Can you suggest some well-written introductory texts about coordinate system projections? Let's assume I'm working with the CH1903 map projection, ...
8
votes
6answers
1k views

Looking for a tool to convert DD to DMS

I am looking for either an online tool or one that I can download to convert DD to DMS. For example, I want to convert from: 41.590833, -93.620833 to 41° 35′ 27″ N, 93° 37′ 15″ W ... Those are the ...
2
votes
3answers
1k views

Local Coordinate to Geocentric

The ultimate question, I need a transformation matrix to take a point in local space representing a roughly 500m x 500m place in New Mexico centered at -108.619987456 long 36.234600064 lat. The final ...
5
votes
1answer
10k views

QGIS - Change unit of measure from degrees to meters

I am running QGIS 1.7.0 on windows, and I donwloaded a shapefile of census block group boundaries from TIGER. This file appears to be in the WGS 84 coordinate system, and when I open it in QGIS the ...
14
votes
3answers
2k views

Do ArcGIS SpatialReference object factory codes correspond with EPSG numbers?

I've got a project where I'm reading in geometry objects from text files to put them in ArcSDE. These geometry objects have an associated EPSG code, and I'm looking for a way to ensure they're in the ...
7
votes
2answers
2k views

How is EPSG:4326 data 'projected' in a 2D map?

I like to think I'm relatively well-versed in datums, projections, and coordinate reference systems, so if this is a stupid question I will suffer eternal shame. OpenStreetMap data is stored in WGS84 ...
4
votes
4answers
1k views

What is the projection of WGS84 in GIS software?

WGS84 is a reference ellipsoid that determines coordinates of every point on Earth using latitude, longitude and height about the its surface. This ellipsoid is often used as a base to make maps. ...
10
votes
10answers
6k views

Batch convert lat longs to UTM?

I've got a .csv file that contains a long list of latitude and longitude points. Is there an efficient way to batch convert the list into a projected UTM coordinate system? Thanks.
3
votes
1answer
70 views

Help identifying a coordinate system

I have some "latitude" and "longitude" data that describes the Silverstone motor racing circuit in the UK. The coordinates look something like this: latitude longitude +03124.27986 +00061.07652 ...
1
vote
2answers
340 views

Predefined Coordinate Systems missing in QGIS 2

in QGis 1.8 were lots of predefined coordinate systems (national projections). Where have they all gone in qgis 2.0? I specifically need the Gauß-Krüger-Projections Zone 1 to 5. Is there any plugin ...
-2
votes
1answer
64 views

How to Draw/plot or identify in GoogleMaps with below PointData

How to Draw/plot or identify in GoogleMaps with below PointData? Below are the points generated from spatial cadastre software. PointName Xpos Ypos _1 341.0926 527.9615 _10 669.1454 ...
18
votes
3answers
78k views

Does Y mean latitude and X mean longitude in every GIS software?

Now it's been 3 days I am using Mapinfo and it has Y as latitude and X as longitude. Is that the same case for all mapping software? As for any country their respective value is multiple of 1 or -1. ...
17
votes
5answers
3k views

How do you best deal with data that spreads across UTM Zones?

I have data that spreads across two UTM Zones GDA/MGA94 UTM Zone 55 and 56. I have layers such as a cadastre, roads, pipelines etc where I want to store measurements like lengths and areas in metres ...
7
votes
3answers
4k views

Geodetic Coordinates And Latitude, Longitude

Would it right to say that geodetic coordinates (phi & lambda) are the same as latitude & longitude?
4
votes
3answers
735 views

How do I specify a CRS for a fictional game map in QGIS?

I am about to start playing a steampunk RPG game called The Iron Realm, which uses a fictional world map. I have recently started using QGIS v1.7 and have no real experience with GIS sysstems. I have ...
13
votes
3answers
3k views

Lon/lat transformation

First I should clarify I don't have previous experience with the field, so I don't know the technical terminology. My question is as follows: I have two weather datasets: The first one has the ...
6
votes
3answers
3k views

Writing world file when exporting TIFF using ArcPy Mapping?

According to documentation, the options are: Syntax ExportToTIFF (map_document, out_tiff, {data_frame}, {df_export_width}, {df_export_height}, {resolution}, {world_file}, {color_mode}, ...
5
votes
3answers
330 views

Why some coordinate systems define x-axis as northings and some as easting?

The definition of north and east are pretty straight forward to grasp but only becomes difficult when used interchangably with x-y coordinates which have varying definitions for the direction of the ...
2
votes
1answer
329 views

How to translate coordinates on the earth

I am trying to translate coordinates. I have a set of coordinates for city A which I need to map to city B, given a point P1 in city A maps to P2 in city B. How do I do this? This problem would be ...
5
votes
2answers
641 views

What is the origin of the Degrees, Decimal Minutes format?

In my experience, for most non-GIS folks, the most commonly used and understood coordinate system is good old Latitude and Longitude, displayed as degrees, minutes, and seconds (DDMMSS.ss). In GIS, ...
5
votes
2answers
4k views

Convert x, y position in georeferenced image (with world file) to longitude, latitude?

What steps do I need to do in order to calculate longitude and latitude for a specific pixel in a georeferenced image? For example this image ...
4
votes
1answer
423 views

How to specify coordinate reference system (CRS) for scalebar that is different to project CRS?

Is it possible to specify a coordinate reference system (CRS) for the scalebar that is different to the project CRS? For example, my project CRS uses geographic coordinates (lat/long), the reason ...
4
votes
3answers
1k views

How can I find out how to convert this point to lat lon?

I have received a shapefile with measurement points to be analyzed, but no matter how I try, I can't find how to convert to lat lon. I suppose it would be good to know the projection but when I look ...
4
votes
5answers
2k views

Can I copy an entire geodatabase with relationship classes and domains and reproject all feature classes from wgs84 to state plane?

I have an SDE geodatabase with several feature classes, tables, relationship classes, and domains. All the feature classes are currently in WGS84 coordinate system. I need an exact copy of the ...
3
votes
1answer
78 views

What is displayed when I am using a geographic CRS for my project

I understand that each geographical dataset has a CRS, and that in order to overlay them, you need to either make sure that all datasets use the same CRS, or re-project some of them (or use on-the-fly ...
3
votes
1answer
441 views

Using QGis for an imaginary plane world

I created an own map for my p&p rpg group and now I want to transfer it into QGis. That's easy to make, but I'd like to have an own CRS for that map but don't know how to use the right proj.4 ...
3
votes
1answer
3k views

Lat/Lon/Alt to spherical or cartesian coordinates

On my previous question, it was advised I convert lat/lon/altitude to spherical or Cartesian coordinates. I'm not working near the poles and it would be safe to assume a spherical earth. What would be ...
2
votes
1answer
73 views

Which projected coordinate system should be used for mapping the US?

I'm on a project requires integrating data for all states in the US. It means I have two roadway datasets and I'm going to assign the attributes of roadways in one dataset to the same roadways in the ...
2
votes
3answers
135 views

Can someone recognize the CRS?

I'm using QGIS 1.8.0 and have some shapefiles with a "User Defined CRS" which I don't recognize. Is anyone able to recognize it? Here is an image of the settings I see on QGIS. Thanks in advance. ...
2
votes
1answer
544 views

How do I get the coordinates of my data frame always in long/lat?

I want to determine the coordinates of my current data frame. To do so I wrote this script: def DataFrame (): mxd = arcpy.mapping.MapDocument("CURRENT") df = ...
2
votes
1answer
618 views

How to move SHP to gdb with ArcView license?

What I need to do is move all the files into an mxd to a newly created gdb, chechking prj, and update mxd reference. I have ArcGIS 10 SP4, license ArcView I studied a bit of Python and get familiar ...
1
vote
2answers
602 views

QGIS layers no longer overlay when Enable 'on the fly' CRS transformation is on

My QGIS project has two layers - one retrieved from GADM (administrative boundaries of Guinea Bissau) and another one of the villages collected in the field using GPS Decimal Degrees - D.ddddd. If I ...
0
votes
2answers
104 views

How can I fix a geoTiff with an incorrect CRS?

Trying to load and plot a raster (it's a DEM) in R, but having problems. Using R I read in a raster file: library(raster) dem <- raster("DEM_Victoria.tif") # >70 MB print(dem) class ...