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CONTRIBUTING.md

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Contributing

Prerequisites

  • Command line development tools (make, git) for your platform
    • Ubuntu: sudo apt-get install build-essential git
    • Mac OS X: Install Xcode and run xcode-select --install from a command line
  • Python and Pip
    • Ubuntu: sudo apt-get install python-pip python-dev
    • Mac OS X (via Homebrew): brew install python, then brew linkapps python
  • jsonschema package (for running make check)
    • pip install jsonschema

Adding new sources

The 'source' documents for this project are the .json files in sources. To add a new imagery source, add a new file to this directory.

Each source must minimally have name, type, and url properties.

See schema.json for the full list of available properties.

Imagery Extent

Local (i.e. not worldwide) sources should define an appropriate extent.

"extent": {
    "min_zoom": 0,
    "max_zoom": 22,
    "bbox": {
        "min_lon": -178.0000970,
        "max_lon": -66.9452845,
        "min_lat": 18.7586966,
        "max_lat": 71.5633329
    },
    "polygon": [
        [
            [lon, lat], [lon, lat], [lon, lat], ...
        ], [
            [lon, lat], [lon, lat], [lon, lat], ...
        ]
    ]
}

The extent polygon property should contain an array of test polygons that, combined, form the valid bounding area for this imagery. In other words, the imagery source is considered valid within any of the test polygons.

Polygons can be created by using a tool like http://geojson.io/

Imagery Dates

Valid imagery dates may be defined with start_date and end_date properties:

    "start_date": "2012",
    "end_date": "2014",

Specifying reduced accuracy dates is complex. For simplicity, the schema allows a subset of ISO 8601 defined in RFC 3339 except that a reduced precision date is allowed. For example, 2013-04-15T14:02:54.05+00:00 is a fully specified ISO 8601 date-time, 2013-04-15 could be used for just the date, or 2013-04 for just the month, 2013 for just the year.

Implementations may round down the end date (e.g. consider 2013 the same as the start of 2013 so to specify imagery taken sometime in 2013, use "start_date": "2013", "end_date": "2014".

Building the combined files

After you've made a modification:

  1. run make check to validate the source files against schema.json
  2. run make to generate imagery.xml, imagery.json, and imagery.geojson