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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1k views

SRID 4326 and geometry conversion

From this line: SELECT ST_AsEWKT(geom) FROM buildings LIMIT 1; I get this result: "SRID=4326;MULTIPOLYGON(((404269.308014269 4543087.6184561,...)))" I'm wondering if the coordinations are ...
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1answer
121 views

What are the geometric principles and GIS techniques that I can use to generate a postcode coverage of my city at street scales?

Postal codes of Brazil and another countries are oriented to distribution logistics, and improvement of reliability in writing the postal addresses; but without much concern for the spatial ...
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1answer
131 views

Why does Find_SRID return zero?

using SELECT Find_SRID('public', 'myTable', 'myColumn'); I get zero as the result, what does it mean? Regards,
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2answers
565 views

What can go wrong in UTM to WGS1984 conversion (shifted data)

I try to convert .shp files to OSM data with shp2osm and ogr2osm but the output data is shifted. Semi-Cross-Posting Warning: I have already asked a questions on the OSM help site, but this questions ...
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2answers
144 views

Which SRS to use for global distance queries?

I have a database with a lot of points in WGS84. Now I am building an cache that performs NN and points in range queries using a KDtree. The point [sic] is that the search radius will be provided in ...
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99 views

How do I determine programmatically what values to add to the proj4js constructor for a CRS or SRS such that I can iteratively render proper overlays

I think this is primarily a GIS based question as far as for example: var crs = L.CRS.proj4js('EPSG:2154', '+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3 +x_0=700000 ...
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2answers
158 views

Coordinate system of a raster file to be introduced for transformation

I am working on raster data using GDAL. When I extract coordinate system information of the files I got this: PROJCS["Geostationary_Satellite", GEOGCS["GCS_Unknown datum based upon the custom ...
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2answers
2k views

ArcGIS Length and Area Calculation Scenarios

Trying to get a handle on how length and area are calculated in different scenarios in ArcGIS. I don't know why I can't find a answer on the feature class fields, but I can't find a precise answer, ...
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0answers
203 views

Adding X,Y data and viewing with existing shape file

Excuse me for a simple question. I have CSV files of X,Y data (in decimal degrees) that I want to add to a map and view with a shapefile of level III ecoregions that I downloaded from the USGS ...
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2answers
1k views

How to add points in degrees + decimal minutes to QGIS?

I try to add geocaches with x,y coordinates in a xls-table to qgis and convert to shp.file. Usally geocach-coordinates are like this: N 51° 29.440' E 011° 56.430' (WGS84) (in german its called ...
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2answers
830 views

Describing a coordinate system in arcpy

I have a python script in ArcGIS 10.1 which takes in a few inputs from the user. One of the inputs is a coordinate system. I would like to test whether the coordinate system the user chose was ...
2
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2answers
303 views

How to calculate the surface using Lambert correction?

i'm using lambert conformal conic , so we have distortions along any given parallel , i would like to get the area used to solve this distortion. I have calculated the area using Shoelace formula , ...
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0answers
70 views

Problems with CRS in Qgis [duplicate]

Possible Duplicate: Raster incorrectly reprojected to OSGB(27700) The crs is clearly off when the gridlines run straight and the map lines run at an angle. I have set the crs to match the ...
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1answer
105 views

keeping the coordinate system of raster files in the resulting raster file after operation with numpy

I'm trying to read as array two raster files using ReadAsArray in GDAL/python, perform some map algebra operation on it using numpy and then write the resulting raster file in GTiff format using ...
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1answer
595 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 ...
2
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2answers
352 views

Problems aligning layers digitized from Google earth into ArcMaps10

I'm a PhD student new to ArcGIS. I'm digitizing features from Google Earth to use in ArcGIS (I work in India, where the mapping in GIS is at best scanty). I drew along a river in Google Earth, saved ...
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1answer
563 views

Coordinate system of a MODIS file to be introduced in GDAL for transformation

I am working on MODIS data using GDAL. When I extract coordinate system information of the files I got this: Coordinate System is: PROJCS["unnamed", GEOGCS["Unknown datum based upon the custom ...
2
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1answer
76 views

Latitude and Longitudes are replaced with zeros when importing excel 2007 worksheet into personal geodatabase

I am trying to import an Excel 2007 data set into a personal geodatabase so I can convert coordinate systems. The data set includes point locations in Decimal Degrees. When I import the Excel ...
4
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1answer
251 views

extracting pixel value from a table in postgresql

I have a table in postgresql that contains ID, row number, column number, pixel value and centroid of the pixel in WGS84 lat-lon system(4326). How could I extract the pixel value by giving a point in ...
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1answer
136 views

Taking a 'custom' map and transforming its x/y co-ordinates to 'real' long/lat co-ordinates?

I was wondering if someone could help me out with a little project I'm working on. I'll try to describe what I'm trying to achieve - if it doesn't make sense, please let me know. I have in front of ...
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1answer
238 views

What coordinate system is this?

I just found a dataset of trees in San Francisco, but I'm unable to determine the system used for the coordinates. Here are some samples: 5998894.045593,2119007.035323 ...
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1answer
325 views

Cannot select a feature using ArcObjects because coordinate systems differ

I'm using ArcMap 10 and Bing Maps Road as base map. Then we have our adding which is programmed using C#. What I'm trying to do is to select a feature (A) that intersects another feature (B, from a ...
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0answers
201 views

Coordinate systems conversion

I have the following task. This is my sample data. WGS84 datum (longitude/latitude): -123.75 36.59788913307022 -118.125 40.97989806962013 Spherical Mercator (meters): -13775786.985667605 ...
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1answer
100 views

Library design: Layer coodinates/origin

I am working on a vector map library where you can add plain image and vector layers to a map. The map itself consists of an infinite coordinate system and each layer is a coordinate system of it's ...
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103 views

Coordinate system for map downloaded Digimap?

I have download a 1: 25000 map from Digimap. It came as a tif file along with a tfw file. When I try to import the tif file as a raster layer, I get the following message: 'this layer appears to have ...
2
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1answer
292 views

How to programmatically determine whether a spatial reference factory code is valid?

I am using the following code segment to create a spatial reference. spatialReferance = arcpy.SpatialReference() spatialReferance.factoryCode = spatialReferanceFactoryCode ...
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1answer
112 views

If the Earth was flat, what unit of measurement would distances between geographic points be represented as?

A whole lot of abstraction- given two longitude/latitude points given from a GPS, I'm using the Pythagorean distance formula to find the distance between them. What unit of length would the distance ...
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0answers
157 views

In Geoserver, Using as a Data Store the Web Feature Server option, but I have a serious problem

I’m using as a Data Store the Web Feature Server option, but I have a serious problem, because Geoserver needs to know what Coordinate Reference System of my data. This information is used for ...
3
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1answer
540 views

QGIS custom CRS for map of manufacturing shop floor

I'm working on a web app that shows a map of a manufacturing plant's shop floor. I've built it in Inkscape and QGIS, but when I try to load it into Tilemill, I get a CRS error. Specifically, it ...
5
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2answers
714 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 ...
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1answer
343 views

ogr: how to use epsg database for RD New projection?

I'm trying to assign this EPSG projection to my newly created shapefiles using ogr. The OGR Projections Tutorial says: ...any geographic coordinate system in the EPSG database can be set by it's ...
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4answers
240 views

How to measure without coordinates?

My current Project is to "map" a turntable in qgis. I know, very unlikely but that's what my teacher wants. My teacher also wants me to measure something in this project (Very specific, isn't it?). ...
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2answers
986 views

shape file coordinate system

I added a shape file of Iran to Qgis. 'Tehran' has 35.6833° N, 51.4167° E coordiantes, however Qgis shows Tehran with 4772860,31296767. How i can view coordinates of a city or location in latitude ...
2
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2answers
679 views

How to use the coordinate system in arcgis 10?

I have a favor to ask. I have a few layers. The layers have been made by a different company. So how do I combine them all together so that they have the same coordinate systems? If there are any ...
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2answers
482 views

UTM coordinate conversion to Geographic coordinates

I have about 500 separate files containing GPS points in UTM coordinates from multiple zones. I am looking for a simple and fast python or Php script that i can use to carry out a batch conversion ...
4
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1answer
432 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 ...
2
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1answer
1k views

Why is my .prj file not being read by QGIS?

First off, I am new to GIS. I am using qgis (1.8.0), and have been given a shapefile containing .shp, .prj, .shx, .dbf, however qgis will not load the .prj file stating an invalid data source. ...
2
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3answers
2k views

Problem with spatial reference system / shapefile projection

I am new to using QGIS and having some problems getting some shapefiles to project correctly. I am using publicly available shapefiles for New York City municipal boundaries found here: ...
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 ...
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1answer
182 views

How do I reproject a arbitrary coordinate system grid to OSGB

I have a polygon grid of a certain shape that has some data associated with it. Unfortunately its not properly projected, being in what seems to be an arbitrary scale and coordinate system (it was ...
2
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1answer
733 views

Convert shapefile in NAD27 from meters to decimal degrees to match xy data?

I have a shapefile of a boundary (polygon) that has the following projection: NAD_1927_UTM_Zone_11N Projection: Transverse_Mercator False_Easting: 500000.00000000 False_Northing: ...
2
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0answers
367 views

PostGIS: ST_Transform function conversion problem

I'm inserting map data from a GML file with srid EPSG:27700 into a PostGIS database table with srid EPSG:4326. I'm using the ST_Transform function as in this snippet: ...
2
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2answers
288 views

Ordnance Survey osgb:BNG spatial reference system not recognized by PostGIS

I'm trying to load an Ordnance Survey GML file into PostGIS using the ST_GeomFromGML function. The problem is that the spatial reference system that is used in the file, osgb:BNG, is not recognized by ...
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25 views

Translate geographical coordinate [duplicate]

Possible Duplicate: Calculating Lat/Lng X miles from point I would like to know how could I translate a geographical coordinate to an specific distance. So for example let's suppose I'm ...
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3answers
361 views

How can I translate a GML definition of SRS to a usual format (e.g. WKT or PROJ.4)?

From GDAL 1.9.0 a new utility is available: gdalsrsinfo. Although it can yield an XML (GML-based) definition from a source equivalent format or file, it seems that it can only read usual GDAL/OGR ...
3
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1answer
190 views

Natural Earth: How to get the position of each country?

I've just split the 1:10m Natural Earth countries into individual JSON files which I plan to render and partially stitch back together using RaphaelJS. The 1:10m map is very big (10mb or so) so ...
5
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2answers
671 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, ...
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1answer
193 views

Spherical Mercator to Cylinder mercator?

Hello I want to create an overlay for google maps. As far as I know google maps using Spherical Mercator, so the system where I read the maps use Mercator but is not specified which (spherical or ...
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4answers
2k views

How to plot a point on a static Google map [png]?

map&markers=color:blue%7Clabel:S%7C40.702147,-74.015794&markers=color:green%7Clabel:G%7C40.711614,-74.012318&markers=color:red%7Ccolor:red%7Clabel:C%7C40.718217,-73.998284&sensor=false ...
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63 views

How can I specify a spatial reference system which has a north pole different than the standard north pole?

I have a geographic spatial reference system (i.e., latitude and longitude) which has a north pole that is not the usual north pole: it's the magnetic north pole at approximately 70.30 degrees north, ...