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Questions tagged [map-projections]

A map-projection transforms the coordinates of the spherical earth to a flat map in cartesian (x,y) space.

A map-projection transforms the coordinates of the spherical earth, usually given in degrees (latitude, longitude), to a flat cartesian (x,y) space.
There is no perfect projection, it can be proved that each projection has a drawback, one have minor others major ones.

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Get all coordinates between two points of a polyline when clicked

I have set up a sample polyline from given coordinates. coordinates = [ [52.908902047770276,-116.015625], [52.908902047770276,-116.015625], [53.12040528310657,-115.6640625], …
h1m4l
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Transforming Simplex Map for UV mapping on a sphere

I would like to dynamically generate a simplex-based image that will map nicely on a sphere in three.js, however I'm having problems with distortion at the poles. Here is the initial map code: def…
morgajel
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Why is scale a function of pi in D3's Mercator projection?

In every D3 map example I can find, the scale parameter of the Mercator projection is set to equal width / 2 / Math.PI. Is this unique to the Mercator projection? What is scale doing that it needs to rely on pi? I'd love to have a more intuitive…
jefflovejapan
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Sending commands to FWTools via Matlab?

I am trying to use Matlab to send commands to FWTools in order to project a bunch of .shp files. I am able to start FWTools from Matlab but I cant figure out how to send it commands without my interaction. So far FWTools starts and my matlab command…
nori
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How to import projection in readShapePoly() function? - R

I am importing a polygon shapefile from Arcmap that has already a projection set and comes with all its files (sbn,sbx,prj,etc). However after I use the readShapePoly function, when I do a summary it looks like the projection information is blank.…
Herman Toothrot
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D3: What projection am I using? / How to simplify with a null projection?

I am attempting to simplify a d3 map on zoom, and I am using this example as a starting point. However, when I replace the json file in the example with my own (http://weather-bell.com/res/nws_regions.topojson), I get a tiny upside-down little…
Mike Furlender
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Render shapefiles in opengl that have a geographic coordinate system

As you know we have two kinds of coordinate systems in GIS : Geographic coordinate systems and projected coordinate systems consider these situations: I have a shapefile that has projected coordinate system, I mean the coordinates of the vertexes…
Sepideh Abadpour
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How to convert WGS84 to ETRS89 UTM with php?

I need to find a way to convert a pair of WGS84 geographic coordinates to ETRS89 projected coordinates (UTM) using php. Example: (lat)37.255205, (long)-5.549390, (height)141.562284 Anybody know how can I to do that? Thank you!!
Acicate
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What does an esri projection file represent?

I have managed to really confuse myself here. I am trying to determine what the associated *.prj file that accompanies an esri shapefile means. If I have a *.prj file that has this in it: PROJCS["WGS 84 / World Mercator", GEOGCS["WGS 84", …
jared
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How to manually convert point features to SVG coordinates

I have set up a d3.geo.path as follows // Projection var projection = d3.geo.mercator().center([LONCENTER, LATCENTER]).scale(MAPSCALE); // Path for projection path = d3.geo.path().projection(projection); My task involves plotting pie charts on a…
grssnbchr
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PostGIS spatial reference ID (SRID) for regular cartesian coordinate system?

I would like to store a polygon as a set of 2D points represented as x, y coordinates of a Cartesian coordinate system. Which spatial reference can I use? Looking at my spatial_ref_sys table, all the spatial references seem to be geography…
Zoltán
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Android - Create google map projections V2

I embedded a PNG image on the map (version 1) using Overlays: .... Bitmap map_scaled = Bitmap.createScaledBitmap(map_png, map_png.getWidth(), map_png.getHeight(), true); .... @Override public void draw(Canvas canvas, MapView mapView,…
Ernesto Rodriguez
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interpreting map-projection details

Not an expert in reading or interpreting map-projections. I have data set with the following description. The coordinates are in Albers Equal Area Conic projection, with the following projection settings: Scale = 1; False Easting(m) =…
Nav
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re-project SGDF with 5 km*5km resolution to 0.05*0.05

Forgive me for me being naive. I am having trouble with re-projecting SGDF. I have an xyz (x=longitude, y=latitude, z=value) 3-column dataset. Longitude and Latitude values are coordinates in EPSG:3035 format. I converted the data frame into a grid…
Nav
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cartesian to geographical/sperical coordinates

I have a dxf file of a town in meter coordinates. I need to extract polylines from the map and convert them to geographical coordinates. My idea is to add 3 or 4 points on the map with known coordinates. I will place them using google map as…
yoh
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