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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611 views

How to represent clustering of geographical points on map in STATA?

I've plotted a map on STATA using user-written program spmap and have also obtained the grid for my space using spgrid program. Now I want to see where most of my data points are clustered on map. Is ...
2
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1answer
230 views

Problems with NAD27 projection in QGIS

I have some data that is in NAD27, but I am having a hard time displaying it in QGIS. I think that the problem is with the CRS. I cannot seem to find the correct NAD27 option. The closest one seems ...
4
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1answer
129 views

Problem with custom projection definition in Qgis

I want to define a custom crs valid for Mexico. The context is that older cartography in Mexico is based on the NAD27 datum. I wanted to test the following proj4 string +proj=longlat +ellps=clrk66 ...
2
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3answers
917 views

How to handle layers with different spatial references in ArcGIS Runtime SDK WPF?

I am currently writing the "Zoom to Layer" function for my application. However, the spatial references between my imported layer and my base map are different. Is there a way around this? Can I ...
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1answer
1k views

Convert GPS coordinate to ArcGIS x,y point?

I'm trying to plot some AGSSimpleMarkerSymbol's in a AGSGraphicsLayer. The issue I'm running into is that the data I'm starting with are GPS coordinates (lat/lon). I'm using AGSPoint to plot the data, ...
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1answer
320 views

matching georeferenced jpg with GPS data in WGS84 [closed]

I have imported my georeferenced jpg which I believe (on the basis of metadata in xmml file) to be in the NZGD2000 TM coordinate system. metadata: Origin: 1.76759e+06,5.94938e+06 Pixel Size: ...
2
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1answer
144 views

Need to convert from ISpatialReference to SpatialReference

I am attempting to write a method in C# that will accept as input, an ESRI.ArcGIS.Geometry.ISpatialReference object and convert it to an ESRI.ArcGIS.Client.Geometry.SpatialReference object. I need ...
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1answer
3k views

What is the relationship between ITRF and WGS84?

Why are there people saying that "I am using WGS84(ITRF96)"? There are newer version of ITRF. Will WGS84 follow it? If so, what will be the influence to us?
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2answers
2k views

Location of Coordinate Systems folder in ArcGIS 10.1

To make it easier to find and select the 3 or 4 coordinate systems we use most often in ArcGIS 9.x and 10.0 we would copy them to the top of the Coordinate Systems folder, generally located in ...
2
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0answers
41 views

Spatial indexing of a point pattern in R [duplicate]

I have a point pattern and a tessellation (grid) in R. Is there a way to spatially index each of my points? In other words, my tessellation grid has n quadrats, I would like to know for each of my ...
2
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0answers
120 views

What's the difference between CRS 4326, CRS 4978, and CRS 4979?

CRS 4326, 4978, and 4979 are all based on WGS84. 4326 is called "geographic 2D" 4978 is called "geocentric" 4979 is called "geographic 3D" What are the differences between these three? And why ...
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1answer
300 views

Can I say WGS84 is more accurate than NAD83 in terms of their reference ellipsoids?

Other than its application, can we say the reason of common adoption of WGS84 is due to its accuracy?
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1answer
385 views

Coordinate system in aerial imagery

I am calculating WGS84 coordinates of points in an aerial image, given the WGS84 coordinates of the center of the image and the ground distance width and height (calculated from altitude and lens ...
9
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1answer
695 views

How can I see the coordinate transformation parameters in QGIS?

How can I see (and edit if possible) the transformation method and parameters used by QGIS for "on-the-fly" transformation, and then for saving data in another CRS? Like in ArcGIS? Here is the ...
5
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1answer
184 views

How do I make the scalebar accurate when I am working with a google satellite image in QGIS?

I start a project in QGIS. I set the CRS to anything (in this case I use EPSG=26918 a NAD83 datum). I also enable on the fly projection. Then I import a vector. In this case a kml, which I believe is ...
2
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1answer
1k views

Converting geographic coordinate system in R

I have points in geographic coordinate system and I wanted to convert them to swiss grid (CH1903+). Sample data: id lon lat 2 7.173500 45.86880 3 7.172540 45.86887 4 7.171636 ...
5
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1answer
520 views

How to Display the World Map in Projected Coordinate Systems

I am trying to create a simple presentation map and I download the global level country boundaries shapefile from http://www.diva-gis.org/Data. The layer coordinate system is in Geographic Coordinate ...
5
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1answer
167 views

Where is the Spatial reference ID stored in SpatiaLite?

I have loaded a shapefile into a SpatiaLite Database using the spatialite-gui. In which table is the Spatial reference ID or EPSG code (of the stored data)stored in SpatiaLite?
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1answer
376 views

QGIS 1.8.0 - Define shapefile as UTM 15 NAD83 Feet

I have a shapefile which the .prj file says it is ...
8
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2answers
1k views

Nearest point on a line ( Spherical / Mercator projection )

I have a line (Ax,Ay - Bx,By) over a mercator projection (google maps) and a random point (Cx,Cy) nearest to that line, i would to know the closest point (transparent blue on the image) over that line ...
4
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2answers
6k views

Convert X,Y State Plane coordinates to decimal degrees

I have 1000's of data point I need to convert from North Central Texas 4202 into Lat/Long decimal degrees. Can someone give me a conversion equation so I can quickly convert using excel? I have only ...
2
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1answer
660 views

Reprojection from WGS to Slovenian Gauss Kruger in QGIS

I have gpx file (track) in WGS84 (EPSG: 4326) coordinate system from Garmin GPSMAP 62 which is right projected in BaseCamp and MapSource. When I save track as *.GPX and import it to QGIS and use ...
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1answer
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 ...
2
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1answer
120 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
127 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
544 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 ...
7
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2answers
141 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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0answers
95 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 ...
2
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2answers
157 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 ...
11
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2answers
1k 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
198 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 ...
3
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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 ...
5
votes
2answers
776 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
votes
2answers
301 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 , ...
1
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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 ...
1
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1answer
103 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 ...
4
votes
1answer
577 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
votes
2answers
337 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 ...
3
votes
1answer
526 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
votes
1answer
75 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
votes
1answer
230 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 ...
1
vote
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 ...
2
votes
1answer
224 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 ...
3
votes
1answer
317 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 ...
2
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0answers
200 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 ...
2
votes
1answer
99 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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0answers
100 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
votes
1answer
282 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 ...
0
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1answer
111 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
156 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 ...