# Tagged Questions

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

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### What is the DNSC08 Mean sea surface model ellipsoid based on?

Does anyone know what Danish Space centre DNSC08 mean sea surface model uses as the reference ellipsoid? there is no meta data on the web site: ...
1k views

### Bearing/Course/Heading in WGS84 ellipsoid model

There is a common formula for computing the initial bearing for a course from lat1, lon1 to lat2, lon2. (And yes, I'm aware that the course will change when traveling). atan2( sin(lon2-lon1) * ...
60 views

### problem creating and editing features at extent edges

I'm in the process of creating a polyline feature layer of tectonic plates. I'm working with WGS-84 reference system, which means the extent is +-180 in lon, and +-90 in lat. In order to create the ...
65 views

### Find gravity normal by ECEF or GPS coordinate of point

How to find gravity normal by ECEF or GPS coordinate of point? Is it the same as normal to elipsoid? Is this ordinary way to calculate normal to ellipse? I'm not quite sure which altitude is ...
86 views

### Converting from flat earth to WGS84 with python

I'm looking to move from basic 2d Cartesian coordinate system into WGS84. I know my starting coordinates, however all intermediate points are x/y/z points. of an origin 0,0,0 . Mathlab has a ...
610 views

### Returning distances in meters from Near (Analysis) tool of ArcGIS for Desktop?

I'm trying to write a python program that returns the distance from each point in a set to the nearest road. Specifically, I was looking for any points within 10 meters of the roads. Both sets of ...
258 views

### SRTM elevation data question

I have a question concerning the SRTM elevation data (http://srtm.usgs.gov/). As a little thought experiment, assume I want to build a 3D model of the earth's surface as a point cloud. The earth's ...
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### Re-projecting WGS84 to OSGB in SAGAGIS

I took some points with a GPS, and I'm trying to convert from GCS to OSGB 1936 British National Grid in SAGAGIS. I'm working with a shapefile. To reproject the vector layer to the OSGB projection I ...
221 views

### Height of the geoid in ECEF coordinates

I know that the relationship of geoid height N and ellipsoid height h to orthometric height H is defined by H = h - N, but what if I have some position in Earth-Centered-Earth-Fixed (ECEF) ...
979 views

### Projecting a Raster from WGS84 to planar Equal Area to Calculate Area: How to Select the Cell Size?

I have a broad question on how to calculate the 'correct' cell size for a raster when analyzing an area not at the equator. My goal is to project a land cover raster provided in GCS WGS84 to an equal ...
119 views

### is ellipse inside ellipse in WGS84 ellipsoid

My question is quite clear: Assume that there is an ellipse, namely EL1. Parameters of the ellipsoid are (focus11 [latitude, longitude], focus12[latitude, longitude], radius1). And a second ellipse, ...
224 views

### projection discrepancy with gdal (1.9) and proj4

I boiled the problem down to that python example: import sys try: from osgeo import gdal from osgeo import osr except: import gdal import osr if __name__ == '__main__': version_num = ...
1k views

### 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 ...
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### from/to ellipsode to/from cartesian conversion

i am trying to convert from/to ellipsoidal coordinates (lat,lng,alt) to/from cartesian(x,y,z) i wrote the below code to do the conversion, but given the initial values of the gpsLat and gpsLng i ...
122 views

### GeoTools: Lambert72 to WGS84

I am trying to convert coordinates (and polygons from com.vividsolutions.jts.geom) in Lambert72 (EPSG:31370) to WGS84 (or the other way around). I'm using the org.geotools.referencing CRS and ...
84 views

### WGS84 Lon/Lat from pixel x/y in a georeference image

I'm quite a newbie in GIS. I need to compute (without using any existing lib/tool) the longitude & latitude (WGS84) corresponding to the a pixel, inside a (georeferenced) map image. I know: ...
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### Inputting Longitude and Latitude in CSV from Geotagged, Photo Coordinates (WGS 84)

I am trying to take Geotagged picture coordinates and put them into a CSV file to display in QGIS as point values. Using Picasa, I can see that the picture coordinates are in the correct locations on ...
45 views

### WGS84 to OSGB, using VB script

first post from an occasional programmer... I have adapted someone else's VB code to convert lat long to OSGB for UK locations. In essence my code converts a Google API location returned from a text ...
103 views

### Auto-Sanitizing illegal PostGIS WGS84 (lat, lon) coordinates

I have just stumbled upon what seems to be a very curious behaviour by PostGIS. The XYZ point -117.0, 32.0, 0 in WGS84 (SRID 4326) is legal: items=> SELECT st_y(st_geomfromtext('POINT Z (-117.0 ...
179 views

### Determine lat/lon intersection on earth from point in space along 3d line

I have a known point in space with a lat,lon,alt. It has a camera with a line of sight and a angle of field of view. I can take the central point and calculate each corner vector of the field of view, ...
113 views

### convert headerless flat binary files to tif

I have set of headerless flat binary files (those are out put files of TIMESAT software). I want to convert those to .tif format. I did it using ENVI. but it does not overlap with the original input ...
86 views

### Node.js transformation from NAD83 to WGS84

I've used the excellent npm shapefile library to import Canadian electoral districts into MongoDB. Here's a sample file: http://ftp2.cits.rncan.gc.ca/pub/geott/electoral/2011/fed308.2011.zip Is ...
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### My map is little bit off

I am pretty new in GIS things and i have been learning how to use QGIS. Most of the maps are fine, but yesterday I went to GIS center at my University and I got the maps of my country that I will be ...
326 views

### GeoTools: SimpleFeatureCollection to KML error CoordinateReferenceSystem

I want to export a SimpleFeatureCollection (Read from a MySQL DB) to a KML file, here is my code used to read the infos into the console: private void featureCollectionToKML(SimpleFeatureCollection ...
506 views

### Get the distance between 2 WGS84 GEOSGeometries

I currently want to check if 2 given GEOSGeometry objects of type Point are within 100m of each other. (length flexible) Looking at previous asked questions on this topic, most of the answers were ...
180 views

### Convert MapCoordinate from WGS 84 and vice versa - ESRI MOBILE 10.0

I am seeing a strange issue in 10.0 mobile version. If a convert a coordinate (x.x,y.y) to WGS84 using mobilecache1.spatialreferece.towgs84 and if I convert the resulting GPS coordinate back to map ...
420 views

### Conversion From Transverse Mercator To Longitude & Lattitude

I have to transform (7-parameters datum transformation) coordinates from northings & eastings to lattitude & longitude. Following are details of source coordinate system(i.e. northings & ...
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### Converting from ellipsoidal heights to orthometric heights (EGSA87)

I try to conver from ellipsoidal to orthometric heights with arithmetic function. In input raster 2 i put WGS84.img from \peodata\geoid folder.The results are not right. And now i have the question. ...
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### Can I assume that ENU Coordinate are already projected?

I have an application where I need to track a vehicle position in range of max 50km. I implemented the ENU coordinate system so my future calclutaion would become easier to impelement (e.g. generating ...
111 views

### Convert WGS84 coordinates to ECEF Cartasian (XYZ) coordinates using pyproj

I need to convert WGS84 to ECEF to map some points to a 3D sphere. I've trawled through the pyproj docs, but can't find specifics on the matter. Basically I want to input the WGS84 GPS lon/lat ...
40 views

### Can I use a polygon envelope I get from JavaTopologySuite(.NET port) in an R-tree implementation? (wgs84 to spatial)

I'm using this implementation of https://github.com/enyim/RTree. I use the .NET port of JavaTopologySuite to create some polygons and then get their bounding rectangles. IPolygon p = ...
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### Triangulation of Cell Towers using MSQL Server Spatial

I need to triangulate a GSM Device by using known cell towers locations and GSM readings. All Data is in a MS SQL Server as Geometry Types. herewith an example of the data : here is also a SQL ...
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### ArcGIS/ ArcPy - XY coordinates of feature class does not match calculated geometry XY

Tested on: different workstations, different Windows versions; ArcGIS Desktop 10.3, different license levels Background: I use the Google Maps DistanceMatrix to calculate drive times between two ...
290 views

### Projection Transformation from ETRS89 LAEA to WGS1984

I am having difficulties to transform a Shapefile in ArcGIS 10 from ETRS 1989 LAEA to WGS 1984 N33. I have 2 files: a) in WGS1984 N33, with a grid of 10x10km, b) in ETRS 1989 LAEA, with small ...
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### How to choose a projection for area measurement on building to continental scales?

I have many geographical objects described as polylines, polygons, multipolygons. All objects are in WGS84. Object could be: a building, stadium, park, street, highway, city, state, even country and ...
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### Estimating world position of origin of coordinate system based on its members global position?

I have n points of interests (POIs). I have a local coordinate system. For all these n POIs I know there position in this system, that is there x, y, z translation (local position) from origin of ...
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### Interpolating a set of GPS points on ellipsoid earth model

I have a set of GPS (latitude, longitude) co-ordinates along with the time at which the coordinates were collected. Additionally, I have the speed and the heading of the vehicle at those coordinates. ...
109 views

### Escaping the MODIS Swath Projection with GDAL: MOD06_L2: MRT Swath Tool not working

Stackexchange, I am looking at ftp://ladsftp.nascom.nasa.gov/allData/6/MOD06_L2/2012/222/MOD06_L2.A2012222.0800.006.2015062054108.hdf Trying to get the SDS (in WGS84 Projection and as GeoTiff): ...
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### Can I use Redfearn's formula to convert between WGS84 and UTM?

I have GPS data at 1 point per second for several weeks in WGS84 latitude/longitude form. It was collected using a UBLOX GPS in 2015 in Australia (Zone 55s) Would it be correct to use Redfearn's ...
298 views

### Converting coordinate notation from GDA94 to WGS84 gives ERROR 999999?

I am trying to convert my data from GDA_1994 to WGS_1984 using the 'Convert Coordinate Notation' tool from ArcToolbox. I used the import XY data tool to import my csv file with x,y fields (among a ...
157 views

### UTM ED 50 transformation to WGS84

I have a set of navigation shot points (pre 1975) with coordinates that are based on a UTM ED50 zone 33 projection and I need to transform these to WGS84. My procedure has been to load the excel fine ...
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### Erroneous location when converting from a GCS_WGS_1984 to UTM

I have a shapefile map of Belgium divided by cantons that I want to re-project in order to have units in meters and to be able to calculate distances. I know how to do it with ArcGIS Projection tool, ...
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### Polygon Shifting in WGS 84

I'm troubleshooting some discrepancies between intersection results in State Plane and WGS 84. The intersect was ran when both the polygons and points were same PCS ...
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### WGS 84 - NAD 83 with a twist

I have a dataset of GPS field point collected received in WGS 84 but displayed in NAD 83 UTM. I used a field point to inform a total station for a reference starting point, so all my total station ...
593 views

### How to convert between SWEREF99 TM (GRS80) and long-lat (WGS84) coordinate with JMapProjLib (Java version of Proj4)?

I'm making an android app which is reading SWEREF99 TM (GRS80) coordinates from a file, but I need to convert them to long-lat (WGS84) coordinates, and also in the oposite direction (WGS84 -> GRS80). ...
33 views

### Setting correct units for Near tool?

I need to use the near tool to calculate distances between data points and a stretch of coastline. My problem is that when I run the function, the values that come up in the Field of the points' ...
168 views

### How to determine the Geoid model used by GPS receiver?

I have the following NMEA output by Holux M-241 GPS receiver: \$GPGGA,144014.000,2227.0987,N,11410.1382,E,2,6,1.67,32.6,M,-1.3,M,0000,0000*7B I know that WGS84 height is higher than geoid height 1.3 ...
196 views

### issue with QGIS Scale Level

I have different layers of shape files. I have imported all shape files into PostGIS. Now i want to show 3 layers Country, State & District with different scale/zoom level I tried to set scale ...