Map data pre-process(1)

To implement navigation software, suitable map data is critical. Not every map data is suitable for navigation purpose, and map data can be categorized to vector and raster data format. Raster map data and vector without topological information (like route connection data) can only be used for location purpose. With a GPS receiver, it can only tell where you are and nearby hotels, gas station. It’s hard to tell you how you can get to a place –the route to a destination. With link-node, link-link information, a route can be calculated so navigation is possible.
Based on the map data I can get, pocket streets China actually includes 2 products: Location and Navigation
Guidebee(Raster/Vector) Location
Guidebee(Raster/Vector) Navigation
Now comes the question, where can I get the original map data? One is from internet like Google map. An program can be written to exact the raster map data from Google map server and store the map images file to local disk for later use. Or online map with network connection.
Another way is buying map data from some map company. Currently I have some map data in MapInfo format. A parser program can be written to convert MapInfo tabs into access database, and then convert the access database into some specially designed map data for effective access.