https://github.com/bensheldon/nodetiles-311dailybriefing

Database backed map tile/UTFGrid renderer.
https://github.com/bensheldon/nodetiles-311dailybriefing

Last synced: about 1 month ago
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Database backed map tile/UTFGrid renderer.

• Host: GitHub
• URL: https://github.com/bensheldon/nodetiles-311dailybriefing
• Owner: bensheldon
• Created: 2012-05-03T17:14:11.000Z (over 12 years ago)
• Default Branch: master
• Last Pushed: 2012-05-03T17:17:55.000Z (over 12 years ago)
• Last Synced: 2024-05-02T06:08:36.188Z (7 months ago)
• Language: JavaScript
• Size: 18 MB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
NodeTile: Occupy Map

====================

_This is a proof-of-concept map of Occupy sites based on data from [Chris Herwig's CartoSyling/Occupy Streets project](https://github.com/kleinjos/carto-styling/tree/master/occupy-streets)._

This is a dirty hack to do server-side map tile rendering using geojson/shapefiles. Map tiles are rendered using node-canvas--a [special version](https://github.com/bensheldon/node-canvas-heroku) that includes a pre-compiled Cairo binary that works on Heroku--and requested via a standard leaflet map. This demo currently renders Baltimore neighbrhoods.

Big THANKS to [Tom Carden](https://github.com/RandomEtc) whose [original gist](https://gist.github.com/668577) inspired this project. He also has other very [useful](https://github.com/RandomEtc/nodemap) [projects](https://github.com/RandomEtc/shapefile-js).

Installation on Heroku

----------------------

1. Clone it

2. Within the directory, `heroku create --stack cedar`

3. Setup your heroku environment variables for node-canvas-heroku

   

        $ heroku config:add LD_PRELOAD='/app/node_modules/canvas/cairo/libcairo.so /app/node_modules/canvas/lib/libpixman-1.so.0 /app/node_modules/canvas/lib/libfreetype.so.6' --app 

        $ heroku config:add LD_LIBRARY_PATH=/app/node_modules/canvas/cairo --app 

   

   IMPORTANT: replace the `` at the end of each command with your Heroku app's name, e.g. 'furious-sparrow-2089'

4. `git push heroku master`

5. Rejoice / Open an issue that these instructions are inadequate

Local Development

-----------------

For local development, you need to install node-canvas manually and from the normal source (NOT node-canvas-heroku): npm install` node-canvas`. Then just run `node app.js`.

How it works / How to modify it

-------------------------------

This application renders PNG map tiles as well as UTFGrid interaction tiles from static geojson files (though it would be relatively trivial to load geojson from a live database instead). Those geojson are loaded into the `Layers` list along with some basic style settings. When a specific tile is requested, a new canvas is created and the Layers, then Features are stepped through and drawn to a canvas, which is then streamed back to the requesting client as a PNG. UTFGrids are rendered in much the same way: they are drawn as a raster where each feature is assigned a unique RGB value; the resulting raster is then read out to create a UTFGrid.

Shapefiles

----------

Within the `/geodata` directory are GEOjson files from the [datasf.of](https://data.sfgov.org/) (transformed via ogr2ogr).

* San Francisco Shorelines

* San Francisco Street Centerlines

* San Francisco Parks

* San Francisco Parcels (is huge and crashes Heroku when loaded; >500MB memory)

And some others, including world outlines from [Natural Earth](http://www.naturalearthdata.com/).

Contact

-------

Email me at [email protected] or open an issue.