[GIS] polymaps & poly… polygons

cartographygeojson

I've been playing with Bing Maps + Polymaps recently.

It has become apparent that Bing is the only mapping resource available to Polymaps that includes satellite imagery. Is this true?

I am trying to accomplish drawing many polygons of different sizes on a map, and filling them with different colors depending on what they represent. Furthermore, I want each of these polygons to be clickable.

I understand that to load geographical data onto a map with Polymaps, you either use .features() or .url() as part of the geoJSON object.

I have .features() working, but by using this function the polygon data must be embedded into the javascript file itself – as in:

map.add(po.geoJson()
        .features([
    {
      "geometry": {
        "coordinates": [[
[[-63.599925935268395,44.64018531837119],[-63.599789142608664,44.640219671024646],[-63.59973818063736,44.6401452402498],[-63.599877655506134,44.64010707058464],[-63.599925935268395,44.64018150140844]],

[[-63.59986692667008,44.639874235083376],[-63.59975695610047,44.63991431339196],[-63.599697947502136,44.63981507181532],[-63.5998159646988,44.639782627416906],[-63.59986424446105,44.6398723265918]]
        ]],
        "type": "MultiPolygon"
      },
      "type": "Feature",
      "id": "beat:05X",
      "properties": {"name": "05X"}
    }

        ]));

I want this data to actually come from a database and not lie statically within the javascript itself – which tells me I should use the .url() method instead – correct? And if I use the .url() method, I must pass a valid URL template that returns geoJSON… How do I go about this with my own private data? I'm familiar with PHP and mySQL – must I use a spatial database system instead?

And how does a map server like MapServer, GeoServer, and others fit into this? Could I not set up a PHP script to read these templates from the $_GET variable, query a database and return the proper geoJSON string?

I really just need some inspiration, a few pointers to set me on my way and kill some of the doubts I have. I've found myself just digging around the stackexchange and googling everything from map servers, to geo spatial databases – you name it, I've probably read about it, but I'm struggling putting the pieces together.

Long winded question but once these things are clarified, I should be in a much better position.

We can remove polymaps from the equation if there are substitutes.

In summary, I'm looking to take a large number of polygons from a database (PostGIS?) of all different shapes, sizes, colors, and transparencies, and plot them on a map. That's essentially it! Polymaps has vector graphics + I thought getting this on the go would be trivial given the above code… we can scrap it if you have other ideas. What is the best solution? My only business requirement is that Satellite Imagery be enabled…Which means we're working with Bing or Google.

Best Answer

If you're talking about GeoJSON you can use any kind of database, and backend server, you want so long as it:

  1. Expects to receives TMS or /{zoom}/{x-coord}/{y-coord}.json style URLs and can convert Z/X/Y in to a bounding box.

(Take a look at something like Tilestache (.org) if you want/need to see the math involved in doing that.)

  1. Returns GeoJSON.

For styling , and adding interactive bits, to the data results you'll want to define a "load" function using the layer's on() method. For example:

var l = org.polymaps.geoJson();
l.url("http://example.com/tiles/{Z}/{X}/{Y}.json");
l.on("load", function(e){ ... });

The Polymaps site has lots of good documentation and example code, but I've also included the slides and sample code from a Polymaps workshop I did recently:

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