Via the Mapperz Blog, Nico Goeminne has created a reverse geocoder using the Google Maps API that brings up the closest street to a point of interest. Select a country/area that Google Maps supports geocoding for, zoom to the area in that country you’re interested in, and click on the map at your location of interest to create a marker. You’ll get the latitude/longitude of the point you clicked on, the name of the closest street, and the reference latitude/longitude for that street. A maximum of three markers on the map at one time, and a limit of 10,000 lookups a day if you use the source code for your own purposes.
For the US, more address-specific reverse geocoding is available at both the Reverse Geocoder for the United States and the Geonames Reverse Address Geocode.
The classic functionality for Google Maps is the computerized equivalent of “sticking a pin in a map”, albeit a very fancy pin with the ability to hold and display additional information. ZeeMaps takes that simple Google Maps functionality and moves it towards something a lot closer to a Geographic Information System. With ZeeMaps you can:
- Create standard maps, housing maps (specialized real estate data attributes), or IP maps (data markers based on location of IP address)
- Import and export data in CSV format.
- Import a list of addresses and have them automatically geocoded and plotted. Or, import data with latitude/longitude coordinates.
- Define attribute fields for your data, then filter your data based on those attributes.
- Annotate the map with text (separate from the data markers).
- Display data in map form, list form, or both.
- Select data points based on distance from a specific point (spatial selection).
- Publish maps on the Web, either in read-only format, or allowing others to add and modify points. You can also select subsets of data that is displayed, while hiding other datasets.
- Associate and upload pictures and audio files with data markers.
- “Print” the map in PDF format.
The service is free, and can be used without registration (though registration makes tracking and managing multiple maps easier). The interface is intuitive, and there’s a decent help section. Although some operations take a few more steps to accomplish than I would like, overall there’s nothing major to complain about; it’s a great Google Maps service, especially at the price.
The Geonames website offers a number of useful geocoding services:
- Enter a name, and get back:
- A list of the first fifty geographic features in their database that include that name
- The feature coordinates
- A link to let you plot the location of that feature in Google Maps, along with fifty other nearby features
- Links to download those features in “csv” spreadsheet format (looks more like tab-delimited to me), or a png image that shows the selected feature plotted as a red point on country line graphic:
- A web-based geocoding service
- A postal-code lookup service
- A downloadable copy of the geocoding database, by individual country, or combined into a single 150 MB file for all countries
There’s a handy Google maps site that lets you place a marker, gives you the position, and then lets you convert that position into a number of geographic text formats.
Continue reading ‘Convert A Google Maps Point To Multiple Text Geographic Formats’
An earlier post covered a Google-Maps-based reverse geocoder, where you could click on the Google Map interface, and get a list of addresses close to that point. Reverse Geocoder for the United States is another Google-Maps-based application in the same vein. While it doesn’t have as many features as the Geonames reverse address geocoding site, it uses the Google Maps interface better, with a larger map display (one of the largest I’ve seen online) and the sliding zoom control (missing from the former site).
It’s easy to use: click on a point on the map, and you’ll get a marker placed there, and the latitude/longitude displayed in a box at the upper right. Click on “Submit point”, and the closest addresses to the selected point will be displayed as markers on Google Maps, and in a list on the right. Click on an address on the right, and a marker balloon will pop up on the map at the corresponding address. It also gives you the Zip+4 postal zip code for the address, which the Geonames site doesn’t. You can also enter a latitude and longitude in the upper right separated by commas, submit the point, and get similar results. A companion site does geocoding - submit an address, get back the latitude/longitude, and the address plotted in Google Maps (make sure you include either the city/state or zip code in the entered address).
Coverage is limited to the lower 48 US states and Alaska. Geocoding seems to use the Tiger database, whose accuracy varies depending on location.
If you need to identify a township or section on map, or plot Public Land Survey Systems (PLSS) boundaries, you can get this data from the Land Survey Information System website, managed by the BLM. Shapefile data is available for most of the US, grouped by state and/or county, in the NAD83 datum. File data includes township, section, subsection, latitude/longitude, and metadata. Note: Make sure you have pop-ups enabled.
There’s also a Township Geocoder web form. Enter the latitude and longitude of the point you’re interested in, NAD27 or NAD83, and get back the state, principal meridian, township, range, section, quarter section, and quarter-quarter section. Or enter the previous data, and get back a latitude/longitude. You can enter individual points, or upload a file for batch point conversion.
As long as I’m on the topic of geocoding and TIGER … The NCSA (National Center for Supercomputing Applications) has an online geocoding application. Paste in US addresses in a comma-delimited format, and you’ll get back geocoded results in either tab-delimited or Excel spreadsheet format. It uses TIGER for the geocoding, so its accuracy will vary depending on the area. There are also geocoders for zip codes, IP hosts, and cities and landmarks, both United States and international.
Stumbled across another free Excel spreadsheet that uses the Yahoo geocoder to convert addresses to geographic coordinates. Simple, basic, but does the job.
A link to a compressed version of ExcelGeocoder is available at the top of this page. Run the program to uncompress the spreadsheet, then open it up in Excel. It requires Visual Basic for Applications, so it won’t currently run in OpenOffice, but apparently VBA compatibility is coming soon to OpenOffice’s Calc spreadsheet and other components.The program uses Yahoo’s Geocoder, and requires you to enter a Yahoo ID in the Settings And Instructions tab, a remainder from when you had to register to use the service. Since registration is apparently no longer necessary, you can enter anything you want for a Yahoo ID, but you have to enter something. Paste your address data into the appropriate columns in the spreadsheet, click on the Geocode button in the upper left, and you’ll get back latitude/longitude for those addresses (up to 5,000 per day is allowed by Yahoo).
If you want to use this geocoded data in Google Earth, you can use excel2kml, or if you save the resulting data in CSV format, you can use csv2kml to convert it into a Google Earth file. You can also convert it into a point shapefile using software that I’ll be covering soon.
