How to reproject a shapefile from WGS 84 to Spherical/Web Mercator projection.

You will need to know the meaning of these terms below. I have given a small description to the acronyms but you can google and know more about them. #1:WGS-84- World Geodetic Systems (1984)- is a standard reference coordinate system used for Cartography, Geodesy and Navigation. #2: EPGS-European Petroleum Survey Group-was a scientific organization with ties to the European petroleum industry consisting of specialists working in applied geodesy, surveying, and cartography related to oil exploration. EPSG::4326 is a common coordinate reference system that refers to WGS84 as (latitude, longitude) pair coordinates in degrees with Greenwich as the central meridian. Any degree representation (e.g., decimal or DMSH: degrees minutes seconds hemisphere) may be used. Which degree representation is used must be declared for the user by the supplier of data. So, the Spherical/Web Mercator projection is referred to as EPGS::3785 which is renamed to EPSG:900913 by google for use in googlemaps. The associated CRS(Coordinate Reference System) for this is the 'Popular Visualisation CRS / Mercator '. This is the kind of projection that is used by GoogleMaps, BingMaps,OSM,Virtual Earth, Deep Earth excetra...to show interactive maps over the web with thier nearly precise coordinates. After reading alot about reprojecting my coordinates from the deepearth project on Codeplex, i still could not do it. After some help from a colleague, i got my ball rolling.This is how i did it. #1 You need to download and open your shapefile using Q-GIS, its the one with the biggest number of coordinate reference systems/ projections. #3 Use the Vector menu-->, Data Management Tools and choose define current projection. Enable, use predefined reference system and choose WGS 84 coodinate system. I first projected the shapefile to A user defined projection[+proj=tmerc +lat_0=0 +lon_0=33 +k=0.9996 +x_0=500000 +y_0=200000 +ellps=WGS84 +datum=WGS84 +units=m +no_defs]. I am personally in zone 36, so i reprojrcted the resultant shapefile again to WGS84-UTM Zone 36N under ( Projected Coordinate Systems-->, Universal Transverse Mercator). #4 Now use the Vector menu-->, Data Management Tools and choose export to new projection. The same dialog will pop-up. Now choose WGS 84 EPGS::4326 under Geodetic Coordinate Systems. +proj=tmerc +lat_0=0 +lon_0=33 +k=0.9996 +x_0=500000 +y_0=200000 +ellps=WGS84 +datum=WGS84 +units=m +no_defs Browse for the place where the shapefile is going to be and give the shapefile a name(like origna_reprojected). If it prompts you to add the projected layer to the TOC, accept. #5 Now, this is not the actual Spherical/Web Mercator projection, but dont worry, this is where you have to stop. All the other custom web-mapping portals will pick this projection and transform it into EPGS::3785 or EPSG:900913 but the coordinates will still remain as the LatLon pair of the projected shapefile. If you want to test, a particular know point, Q-GIS has a lot of room for that. Go ahead and test it. Source.


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Last Modified: April 18, 2016 @ 5:07 am