abaculus

a small block of stone, tile, glass, or other material used in the construction of a mosaic

or,

a library for creating static maps from tiles based on center or corner lng,lat coordinates. Uses node-mapnik to stitch tiles together.

usage

input:

scale: integer between 1-4 and sets resolution (scale: 1 is 72dpi, scale: 4, is 288dpi)

zoom: zoom level

[w, s, e, n]: the bounding box for the west (lat val), south (lng val), east (lat val), north (lng val) for the desired area

x: longitude coordinate

y: latitude coordinate

width and height: desired pixel bounds for a map with a center coordinate. Will be multiplied by scale to maintain resolution.

format (optional): png or jpeg, default is png.

quality (optional): when used with jpeg format, accepts 1-100 and defaults to 80. when used with png format, accepts 2-256 (# of colors to reduce the image to) and defaults to none.

getTile: a function that returns a tile buffer (png or otherwise) and headers given z, x, y, and a callback, such as from tilelive-vector.

limit (optional): max width or height of generated image in pixels. Default is 19008.

// Calculate image bounds from W,S,E,N bounding box.
var params = {
	zoom: {zoom},
	scale: {scale}
    bbox: [{w}, {s}, {e}, {n}],
    format: {format},
    quality: {quality},
    getTile: function(z,x,y, callback){
    			// do something
			    return callback(null, buffer, headers);
			},
	limit: {limit}
};

or

// Calculate image bounds from center lng,lat coordinates and
// pixel dimensions of final image (will be multipled by scale).
var params = {
	zoom: {zoom},
	scale: {scale}
    center: {
    	x: {x},
    	y: {y},
    	w: {width},
    	h: {height}
    },
    format: {format},
    quality: {quality},
    getTile: function(z,x,y, callback){
    			// do something
			    return callback(null, buffer, headers);
			},
	limit: {limit}
};

usage:

abaculus(params, function(err, image){
       if (err) return err;
       // do something with image
	});

output:

an image of desired resolution for the selected area.