Actual screenshot from working prototype
Tiger Mapping and Routing Server (TMRS) is being written in order to facilitate the creation of open source GPS navigation software. Its goal is to simplify street level routing and map drawing functions essential for developing user-friendly interfaces. The data used in this software is available freely from U.S. Census and is called ‘Tiger’.
TMRS is written in C with no platform-specific dependencies. It should work on most POSIX-compliant operating systems even though the development will be done in Linux. Its design will be dictated by the resource constraints of embedded systems. It strives to achieve low storage and memory requirements.
There are two services that are provided by TMRS -
- Street Routing – in this function, the client provides a start and a destination address. The server computes the best path between the two points and returns driving directions.
- Map Server – given a GPS coordinate and area in square miles, the server returns a bitmap that can be used by other applications for a visual display of the area. In addition to above, utility programs for converting Tiger, ESRI, GDT and Navteq data are being developed.
The code for this project is hosted on Sourceforge.net and available for anyone to download. In order to check out from CVS, issue the following commands -
cvs -z3 -d:pserver:email@example.com:/cvsroot/tmrs co tmrs
Sources of Data
- TIGER from U.S. Census Bureau
- The U.S. Census Bureau publishes TIGER data which stands for Topologically Integrated Geographic Encoding and Referencing system. The data is divided by county. So, each county consists of a set of data files, each one containing a particular type of data. These files are not easy to parse, but are free.Download: http://www.census.gov/geo/www/tiger/index.html
- ESRI Shapefile
- ESRI is a company that deals with various types of GIS data. They offer Shapefiles converted from TIGER format at no cost. Shapefiles are significantly easier to parse and conform to a widely used standard.Download: http://www.esri.com/data/download/census2000_tigerline/index.html
- This data is regarded as the most accurate for routing purposes. It contains information such a one-way streets, no-left-turn and Z-levels. Sample data is available from a company called ADCi.Download: http://www.adci.com/products/navtech/index.html
- GDT is another company specializing in GIS data. I have not been able to find free sample data, but you can purchase one zipcode worth of data from ESRI for US$15.Download: http://www.esri.com/data/download/gdt/index.html