map tile compare

map-tile-compare

A single-page web application for comparing a tile layer with a background satellite layer.

Demo

map-tile-compare-demo.mp4

Live examples

• Edinburgh, Scotland
• Edinburgh, Scotland (At twilight)
• Broxburn, Scotland
• Ketelmeer, Netherlands
• Marker Wadden, Netherlands
• Koblenz, Germany
• Germany/Netherlands border

Installing the app

After cloning this repository, run:

$ cd map-tile-compare
$ npm install
$ npm run build
$ npm run serve

This should start a localhost server, usually http://localhost:5000.

For the page to load you'll need to append a URL to a config file to the URL.

http://localhost:5000/#https://example.com/path/to/config.json

Creating a map config

The map data is a compressed JSON string stored in the URL's hash.

Host the following JSON file on a website and update each property to your choosing:

{
  "name": "London",
  "beforeStyle": "mapbox://styles/mapboxUsername/styleId",
  "beforeStyleAccessToken": "xx.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.xxxxxxxxxxxxx-xxxxxxxx",
  "beforeStyleBeforeLayerId": "tunnel-street-minor-low",
  "sourceTiles": "https://example.com/tiles/{z}/{x}/{y}.png",
  "sourceTileScheme": "tms",
  "sourceTileSize": 256,
  "sourceMinZoom": 9,
  "sourceMaxZoom": 15,
  "sourceBounds": [-0.234, 51.454, -0.025, 51.562],
  "referencePhotoImageUrl": "https://example.com/previewImage.jpg"
}

The table below explains the meaning of each property:

Property	Description
name	The name of the map. This is displayed on the splash screen.
beforeStyle	The mapbox style url for the "before" map, typically the "Satellite" style.
beforeStyleAccessToken	The mapbox access token for the "before" map style.
beforeStyleBeforeLayerId	The layer id within the "before" map style where you want to insert your "after" map layer. It's usually the layer immediately above the raster layer.
sourceTiles	The URL to your map tiles.
sourceTileScheme	The schema for your map tiles. Either "xyz" or "tms".
sourceTileSize	The image size of your map tiles in pixels.
sourceMinZoom	The minimum zoom level of your map tiles.
sourceMaxZoom	The maximum zoom level of your map tiles.
sourceBounds	The bounding box of your map tiles. In the order of: left-longitude, bottom-latitude, right-longitude, top-latitude.
referencePhotoImageUrl	The URL to the preview image to display before loading the map.

After creating the JSON, you have two options:

• Store the JSON on an external host.
• Store the JSON file in the public/ directory and run npm run build. The file can then be accessed via http://localhost:5000/yourConfig.json.

Grab the URL to the JSON and append it to the app's host URL.

http://locahost:5000/#http://localhost/5000/config.json

Development

$ npm run dev

Linting

$ npm run lint

Tests

To run end to end tests, in one console run:

$ npm run build:test
$ npm run serve

build:test will build the app with sourcemaps, which will allow for code coverage later.

Then in a different console, run:

$ export CYPRESS_MAP_TILE_COMPARE_HOST='http://localhost:5000/'
$ npm run test:e2e

Code coverage will be generated automatically, and can be viewed in coverage/.

To see the cypress tests actually running in a browser, run:

$ npx cypress open