Bing-Streetside

A library to fetch the "Street Side" image tiles from Bing Maps. This uses reverse engineered API's.

API:

Bing:

Constructing the bing class retrieves the settings + default options. These include the API key, "generation id" along with default settings such as the bubble count

Available methods on this are:

getBubble(id)

This returns a Bubble object

getBubbles({opts})

The available options are:

• count
• box
  • north (latitude)
  • south (latidude)
  • east (longitude)
  • west (longitude)
• center
  • lat
  • lng
  • radius (in meters)

This returns a list of Bubble objects.

May also add in support for geohashes, along with other bounding box formats.

Bubble:

This object represents a "bubble" on Bing, this is 360 sphere.

The sphere consists of an image for each side (front, right, back, left, top, bottom.

Enums:

side

• FRONT
• RIGHT
• BACK
• LEFT
• TOP
• BOTTOM

The available methods on this are:

tileToIndex(x, y, detail)

Converts an x,y coordinate index to a quadtree hash, with the specified number of bits (detail)

fetchXY(side, detail, x, y)

Fetches the tile, returns a Buffer object containing jpeg data.

fetchSide(side, detail)

Fetches an entire side, this fetches them in parallel, although uses a request pool of 16, spread over 2 domains - this approximately matches browser behaviour. The level of detail exponentially increases the number of tiles needing to be fetched. For each value of detail, the number of tiles needed quadruples:

• 0: 1 request (254x254px)
• 1: 4 requests (508x508px)
• 2: 16 requests (1016x1016px)
• 3: 64 requests (2032x2032px)

Example:

new Bing().then(bing => {
  return bing.getBubble(146511614);
}).then(bubble => {
  return bubble.getSide(Bing.Bubble.side.FRONT, 2);
}).then(canvas => {
  let buffer = canvas.toBuffer();
  fs.writeFile(__dirname+'/result.png', buffer);
});

Future Work

Still a fair few breaking changes to be done.

Bing

• caching for the returned info.
• returning a promise in a constructor seems a little dodgy. May change this to lazy load, wait for the internal promise within the getBubble and getBubbles methods.

fetchSide

• Return type needs changing to be a buffer directly, although this isn't ideal for converting it's more consistant.
• May allow retrieving an area by percentage along with how many pixels to render into - do automatic selection of detail based on this.
• May allow specifying an angle rather than a side. 0 degrees being front, 45 degrees being halfway between front and right, etc. Just tricky in terms of how to handle up/down.
• May be interesting allowing returning angles relative to north.

fetchSphere

• return a full 360 degree sphere. This however needs projecting to polar. Maybe we should return an object containing each side individually, with a toPolar() method.