Questions tagged [wgs84]

WGS84 is a geodetic coordinate system, the World Geodetic System 1984 (EPSG:4326).

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118
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123k views

Difference between WGS84 and EPSG:4326?

What is the difference between WGS84 and EPSG 4326? It seems like for a given dataset it might be both WGS84 and EPSG:4326.
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How to reproject MODIS Swath data to WGS84

Im new to GIS and now working with MODIS04L2 Aerosol Optical Thickness image. I need to reproject the image to other coordinate system such as WGS84 for later work but now Im stuck with it. I have try ...
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How do you compute the earth's radius at a given geodetic latitude?

(I see there is an equation on wikipedia that does exactly what I am asking but there is no references. I have no way of confirming the validity of this equation!) I already understand the difference ...
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What is projection of WGS84 in GIS software? [duplicate]

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. ...
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How does QGIS calculate distances when the data is not projected (WGS84)?

I am playing a bit around with Qgis 2.14.6 to understand how it deals with distance measurement. I took a line-shapefile that I saved in 3 different coordinate systems (4326, 32642 and a national one ...
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What causes the GPS offset/shift in China?

I've spent close to two full days trying to understand the nature of the infamous GPS shift in China. After sifting through the noise, two recurring symptoms are that: GPS coordinates (WGS-84) plot ...
10
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3answers
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Converting X,Y coordinates to lat/long using pyproj and Proj.4 returns the wrong coordinates

I'm writing a python script that reads multiple XML files containing x and y coordinates and combines them all into a single csv file. Latitude and Longitude are required fields in the csv, but I am ...
22
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5answers
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Map projection in OpenLayers

I want to overlay some data whose projection is WGS-84 on Google map layer in OpenLayers. But I just can't make them in the right place. I did as follows: map = new OpenLayers.Map('map', { ...
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2answers
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Projecting EPSG:4326 data in 2D map?

I like to think I'm relatively well-versed in datums, projections, and coordinate reference systems. OpenStreetMap data is stored in WGS84 Lat/Lon (EPSG:4326). This CRS is geographic and therefore ...
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Geographic Transformations in Alaska Between NAD83 and WGS84

I have done a ton of research on the most accurate transformation to use in mainland Alaska to convert between the NAD83 and WGS84 datums, but I just can't seem to find a definitive answer. ArcMap ...
9
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1answer
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Is re-projection needed from SRID 4326 (WGS 84) to 4269 (NAD 83)SRID

I have US census data against state boundaries stored as SRID 4269, in an MSSQL DB. The input data used for calculations against that dataset is stored as SRID 4326. As far as I can infer from the ...
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1answer
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Characteristics of different methods to convert ECEF to LLA

I'm trying to convert ECEF (Earth Centered, Earth Fixed) coordinates, which are defined in X,Y,Z, centered at (0,0,0) to LLA (Latitude, Longitude, Altitude). There are a couple of methods I found on ...
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2answers
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Choosing projection for rasterization of random latitude and longitude data in northern Atlantic?

I have a dataset in the WGS84 geographic coordinate system that I would like to interpolate along a grid using Python. It appears gdal_grid is not available through the Python bindings, so I plan to ...
3
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0answers
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OSGB36 to WGS84 reprojection 'error'

First off, I am a recent convert to QGIS and am greatly impressed with its ease of use and speed compared with the ESRI products with which I am more familiar - my congratulations and thanks to its ...
2
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2answers
983 views

On the fly transformation From WGS84 to NAD27 with proj4 code

I want to use this proj4 code: +proj=utm +zone=19 +ellps=WGS84 +toclrk66=-3,142,183,0,0,0,0 +units=m +no_defs or this one +proj=utm +zone=19 +ellps=WGS84 +tonad27=-3,142,183,0,0,0,0 +units=m +no_defs ...
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Choosing UTM zone to use for large country?

I want to reproject OpenStreetMap roads data from the current projection (WGS 84) to UTM, since I read in another GIS SE Q&A(Getting $length in meters in QGIS?) that WGS 84 cannot be used to ...
6
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1answer
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Distances in {Plate Carrée projection - EPSG:4326 - WGS84}

"4326 is just the EPSG identifier of WGS84" [3] Indeed http://spatialreference.org/ref/epsg/4326/html/ says it is a GEOGraphic Coordinate System: GEOGCS["WGS 84", DATUM["WGS_1984", ...
6
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java vividsolutions jts wgs-84 distance to meters

my (java) project uses com.vividsolutions.jts.geom, which provides a distance function. After some googling I finally found that the return value from this function is in central angle degrees, when ...
3
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1answer
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How to convert (geodetic pose + cartesian offset) to geodetic position

I am in search of an algorithm to solve the first/direct geodetic problem precisely in 3D. The input is: a geodetic (not geocentric) position (WGS84, height is above the WGS84 reference ellipsoid) ...
3
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2answers
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Find intercept WGS84 coordinates between two segments defined by (Lat1-Long1 and Lat2-Long2) and (Lat3-Long3 and Lat4-Long4)

I need to determine the WGS84 coordinates for a point that is defined by the interception of two segments represented by two sets of WGS84 coordinates each (lat1-long1, lat2-long2) and (lat3-long3, ...
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Looping Projection in ArcGIS ModelBuilder?

I've got a global DEM raster dataset in WGS84 and need to project this to all WGS84 UTM Zones. So after that I should have 120 raster, one in each Zone. Is there a possibility to automate this ...
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1answer
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Autocad DXF to Qgis and exporting to KML for viewing in Google Maps

/ Background: I have a DWG trace made in AutoCad using Gauss-Kruger coordinate system ( a CRS used in Slovenia ). I'm using AutoDesk Map 3D to transform the coordinate system to WGS84.PseudoMercator ...
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1answer
931 views

What is the formula for converting from WGS84 to EPSG:3071 (Wisconsin Transverse Mercator)

I have GIS software that can do this conversion but I need to know the actual formula / math involved. I'm writing code and need to perform a single conversion (WGS to EPSG:3071) so using a library, ...
14
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2answers
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Converting projected geoTiff to WGS84 with GDAL and Python

Apologies if the following question is somewhat stupid, but I am only VERY new to this whole GIS thing. I am trying to convert some projected geoTiff images to WGS84 using gdal in python. I have ...
9
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2answers
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Merge geojson polygons with WGS84 coordinate

I have a Geojson file with some adjacent polygons and I want to merge them into one. I know it's a recurrent question but I can't find information for polygons with latitude and longitude coordinates ...
14
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1answer
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How to find ring of coverage of GPS Satellite on WGS-84 ellipsoid?

Given the following: Time, t The set of IS-200 Ephemeris data, E, of a GPS Satellite corresponding to time t The ECEF position of the GPS satellite, P=(x,y,z), derived from the time and ephemeris, (t,...
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4answers
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Looking for a pythonic way to calculate the length of a WKT linestring

I was quite unsatisfied with Calculating Length of Linestrings in WGS84 in Miles. It kept me wondering if there is a more convenient, Pythonic way to calculate the length of a WKT linestring according ...
9
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2answers
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How are EGM96 and WGS84 related to each other?

As far as I understand the EGM96 defines the Geoid, where as the WGS84 Standard defines the Ellipsoid. Is the ellipsoid defined in the WGS84 standard defined in a way to maximize the congruency with ...
6
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1answer
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Converting Lambert Conformal Conic to WGS84 using Proj.4

I am attempting to transform data from Lambert Conformal Conic lat/long and I am having some issues with the results. The shapefile I am attemtping to transform can be found here: http://tfr.faa.gov/...
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1answer
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How do I convert Eastings and Northings projection to WSG84 in geopandas?

I'm very new to projections and struggling to convert a map dataset from OSGB36 (Eastings and Northings) to WGS84 (lat/longs). I've used geopandas to import a shapefile. Now I want to export it as ...
5
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2answers
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Stereographic projection of WGS84 ellipsoid on a plane[python]

I would like to ask you for help in following task. What I need to do is to derive local x,y coordinates from latitude, longitude, applying stereographic projection of WGS84 ellipsoid on a plane, when ...
9
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2answers
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Polygons across international dateline [-180..+180 longitude]

I'm trying to generate polygons for satellite orbital swaths. So far I have a method to generate two lines which represent the edge of each swath in [lat,long]. Some of the swath's cross the ...
9
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3answers
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How do I get the area of a WGS84 polygon in square meters?

The following gives me the area of the polygon in square degrees: SELECT ST_Area(ST_GeomFromText('POLYGON((871325.790874952 6105405.3261047,871418.748307692 6105359.72944624,871346.22022442 6105215....
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How to convert from EPSG:4326 to WGS84/UTM 32U?

I am unable to convert from the project's coordinate system to a different one using QGis 1.8.0. I have a .shp file with a certain coordinate system information (WGS84 EPSG:4326 according to qgis). I ...
5
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2answers
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Projected coordinate system for South America

Does anybody have any suggestions for a projected coordinate system for the Northern part of South America? I have a data set that reaches from Venezuela to Southern Peru and I'd like to do some ...
4
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742 views

Shapely polygons crossing the antimeridian

Sample data Consider the following WKT Polygon, crossing the international dateline (antimeridian): POLYGON((176 49,-65 49,-65 11,176 11,176 49)) And the following points: POINT(-140 32) # ...
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1answer
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How to convert resolution in degrees to resolution in meters?

I have a raster data with spatial reference GCS-WGS-1984 (datum D-WGS-1984). Its cell size is mentioned as (0.00045, 0.00045) in degrees. How can I convert this resolution in meters (i.e. linear unit)?...
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3answers
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Which is the most accurate method of measuring distance?

I aim to analyse the accuracy of the various methods of geodesic calculations (distance between two points on Earth)based on the three assumed models of Earth - flat, spherical & ellipsoidal. I ...
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3answers
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Converting Ordnance Survey raster maps to WGS84 webmap tiles

I would like to generate Google/Bing-like map tiles from Ordnance Survey's 1:25000 and 1:50000 raster maps, which are provided as 4000x4000 UK national grid tiles (GeoTIFF). A sample tile can be ...
5
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2answers
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How to calculate new point coordinates from distance and angle using ArcGIS SDK for iOS?

I want to calculate the coordinates of a new point. What I have: The source point coordinates, the distance (meters) and the angle For example: I want to create a point within 100 meters and 45 ...
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4answers
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Proper gdaltransform syntax to transform a list of coordinates?

this is probably a very simple question, but I'm very new to GIS so I just need one last nudge. I've got a sense of the Linux utility gdaltransform and I am feeding it coordinate pairs in line-by-...
4
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1answer
942 views

Averaging Cartesian ECEF coordinates then converting to WGS84 without latitude drift

Preface: I'm unsure if GIS or math is the correct community for this question. I have a set of 9 WGS84 latitude/longitude (degree) pairs for which I need to find the weighted average of. To prevent ...
4
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1answer
203 views

Differences in the longitude and latitude between a LiDAR DSM and an optical image

I've downloaded the UK's LiDAR elevation data (see below) in laz format for a specific region (Tewkesbury) from: http://environment.data.gov.uk/ds/survey#/download From that, a DSM (Digital Surface ...
3
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1answer
191 views

Rhombus shaped pixels when viewing an image referenced in WGS84

Following the Question What is the projection of WGS84 in GIS software?, in the comments section of the answer https://gis.stackexchange.com/a/73578/5256, Jake very well explains that Because the ...
3
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2answers
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How to convert the SRTM DEM orthometric to ellipsoidal heights using ArcGIS or others GIS?

Recently I got the SRTM DEM from Cgiar,which based on WGS84/EGM96. and I merged the tiles to one tiff file. I want to get the WGS84 ellipsoidal heights. According the steps from the Arcgis Help 10.2 ...
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2answers
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How do you convert SRTM HGT elevations from WGS84 into meters above sea level?

I am building a JavaScript script that reads binary HGT files - as generated by the SRTM - and converts the data into bitmaps viewable in your browser. You can try out the script and view the source ...
2
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1answer
979 views

Conflicting WGS84 coordinates between Trimble and Garmin GPS receivers

I am a contractor at a government facility in Nevada. We have our own in-house survey department who, for a number of reasons, still uses NAD27 State Plane Coordinates (Nevada Central Zone 2702) in ...
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2answers
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Convert WGS84 coordinate to Google Map coordinate system (EPSG::3785) with GeoTools and Java

Could you please point me out where can I make such a transformation: Convert WGS84 (EPSG::4326) coordinate to Google Map coordinate system (EPSG::3785), and vice versa.
2
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3answers
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Converting projection?

I got sample shapefiles with the following *prj file content: PROJCS["RGF93_Lambert_93",GEOGCS["GCS_RGF_1993",DATUM["D_RGF_1993",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0]...
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3answers
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Converting WGS84 coordinates to British National Grid Easting/Northings using C#?

I'm looking for some code, ideally C#, to convert a WGS84 coordinate to British National Grid Easting and Northings. Does anyone have this to hand? I tried converting the Javascript code here: http:...