Theory:

Have you seen the GPS maps application in the mobile phone?
 
Here comes the sample GPS map from Anna Centenarylibrary to Marina beach.
 
map.png
 
Using the above Google map, we will be able to reach Marina beach from Anna Centenary Library.  It shows the route to reach the destination that we want.
 
pic.jpg
 
The architecture plan gives us the map of the constructed home. It gives us the way to reach room.