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.