[GIS] download a layer displayed on the google api

google mapsgoogle-maps-apikml

Given the google api displaying a map on some site with layer 'A' on top of it. How can I create a GIS file for layer A (as simply as possible of course)?

Best Answer

Only the Static Maps API and Google Map Maker (Select Countries) are available to download. (Unless you have an Android based tablet or android phone which can download up to 5 areas)

You can create your own paths, markers with the static API https://developers.google.com/maps/documentation/staticmaps/#Paths

Map Maker Countries are available from https://services.google.com/fb/forms/mapmakerdatadownload/ (but read the terms and conditions) This data is in KML and Shapefile formats

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[GIS] Add a OpenStreetMaps road data layer on Google Maps API v3

It's possible but you have to render the custom OSM tiles yourself.

OSM has a generate_tiles python script that renders tiles based on a bounding box setting and a set of XML files (osm.xml includes the others) that control which features get drawn by mapnik on the map tiles.

If you edit the style files to only draw the road network layers you can generate your own set of transparent tiles and display them over any base map.

generate_tiles is a wrapper over mapnik's python bindings that reads data from a postgis/postgresql database so you will have to import OSM data for the region of interest using osm2pgsql.

[GIS] reset “latlng” coordinates on Google Maps

It is actually possible to place your top left corner at 0,0 and your bottom right at 50,50, if you want this. Of course you can place bottom right corner at 10,10, too, or whatever, within the limits: -90/+90 for latitude and -180/+180 for longitude.

The proportion should be:

/*
****************************************** 
Custom Projection - CARTESIAN
******************************************
*/

function CartesianProjection() {
    // map size at zoom 0 is equal to tile size
    this.tileSize = 256;
};

CartesianProjection.prototype.fromLatLngToPoint = function(latLng) {
    var x = (latLng.lng() / 50) * this.tileSize;
    var y = (latLng.lat() / 50) * this.tileSize;
    return new google.maps.Point(x, y);
};

CartesianProjection.prototype.fromPointToLatLng = function(point, noWrap) {
    var lng = (point.x / this.tileSize) * 50;
    var lat = (point.y / this.tileSize) * 50;
    return new google.maps.LatLng(lat, lng, noWrap);
};

Then you should place the center of the map to LatLng(25,25) in the Map options.

Best Answer

Related Solutions

[GIS] Add a OpenStreetMaps road data layer on Google Maps API v3

[GIS] reset “latlng” coordinates on Google Maps

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