Lots of people have them. I like mine. Check it out.
How I did this:
- Installed PostgreSQL and PostGIS
- Tried to load data from the City of Chicago Maps SHP file.
- Discovered the City uses a weird, us-ft based projection. Installed proj4 to reproject data.
- Reinstalled postgis to get proj4 support.
- Realized that doing reprojection inline was crazy, and I couldn’t figure out the right incantation anyway. Installed gdal, which includes a tool called ogr2ogr.
- Recreated my map database schema with ogr2ogr with the following incantation:
ogr2ogr -f PostgreSQL -t_srs EPSG:4326 PG:dbname=maps srcdir. Explanation: -f PostgreSQL specifies output format; -t_srs EPSG:4326 says to translate coordinates from the input spec (which it can read from the .PRJ file) to the standard EPSG mapping #4326 which is mercator lat/long; srcdir contains the unzipped SHP/PRJ/DBF files.
Note that this does not query the database in realtime, once the page is loaded everything is client side. The database is only used for semi-permanent storage of custom markers like zoomlevel and as a reasonably easy way of accessing the data (I’m better with postgres data APIs than I am with csv or parsing shpfiles or whatever).
Cool work! Which reminds me I have to hack this google map API. Thanks for the instrcutions.
this is incredibly cool – you, sir, are a prince among coders.
Round two — Bus maps — is going to be much harder.
Very nice. One problem… there’s no way to pinpoint where you’re trying to get to. Any way to add search capabilities?
Google maps really needs to add bike paths and public transport (at least trains) to their base site.
Nice blog.I like this.
Looks good. I did a CTA map months ago – http://www.tastypopsicle.com/maps/cta.asp. When I did mine I had no idea that the CTA has all of the points for their track plotted out already. I unfortunately had to use a lot of time plotting individual points around the track by hand. Good job on the Blue and Green lines. Where they split is a doosey because, as you saw, you actually have to treat those as separate lines. Otherwise, Google tries to pplt the end points together.
I’d love to see you points that you were able to convert from the CTA to see how close I was able to get to it.
Oh, and the circles “just work”. I used the markers at first and it looked terrible. Someone on the Google Maps discussion group said I should try circles for stations and it does make the whole map more attractive.
I’d like to add this site to my list of Chicago-area Googlemaps, if that’s possible. Would it be ok to post a link on my site to your map?
Chris, that’s fine .. where is that site, out of curiosity?
Is it possible to download this app as an extension in Google Earth?
The El lines are already available in google earth, no separate kml file necessary.