What is Rubber Banding?  Why DO GPS receivers NEED "rubber banding"?  Which ones have it?

What is "Rubber Banding"?
Rubber Banding is the process in which a map program has a Route which runs down a curvy road from intersection A to intersection B.  A "normal" GPS (and some PC mapping programs) just draw a straight line between intersection A and intersection B.

With StreetPilot and ColorMap StreetPilot,  the program "attaches the route to the road" in such a manner that the route from intersection A to intersection B follows the path of the road.  This process is called "Rubber Banding the route to the road".

Why do this "Rubber Banding"?
If you have a GPS which does NOT have Rubber Banding,  as the road curves left,  right and back again,  your GPS will indicate that you are now left of the proper course,  then right of the proper course and so on.  This is because the ROUTE from A to B is a straight line while the ROAD is curvy and may go back and forth across the straight line drawin from A to B.

With the route "Rubber Banded" to the road,  the "go this way" arrow on the GPS will always be pointing you "right down the road" instead of pointing you toward the straight line drawn from intersection A to intersection B as your actual road meanders to the left or right with respect to the line drawn from A to B.

What GPS receivers have "Rubber Banding"?
At present,  only the Garmin StreetPilot and the Garmin ColorMap StreetPilot have this "rubber banding" feature in consumer model GPS receivers.  If you use MapSource version 3.0x or higher,  -and-  use the MANUAL routing features offered in that program,  -and- insure that the corresponding MetroGuide Map is present in the unit,  then you will always get successful rubberbanding.

What happens if I prepare a route in StreetAtlas 7 and upload it to a SP or CMSP?  Will it load properly and "rubber band" to the road?

For "rubber banding" to work,  SP or CMSP  must be loaded with Garmin's  MapSource METROGUIDE maps.  (MapSource Roads and Recreation Maps will NOT "rubber band".)  If you load Metroguide Maps and then upload a route to SP from SA7,  you will find that MOST route segments will "rubber band" to the MetroGuide roads.  Some will not.  This is because the SA7 maps are not quite as accurate as MetroGuide maps and many times,  the intersection designated by SA7 will fall "near" but not exactly "ON" the same intersection on the MetroGuide Map.  When this happens,  the fix (easy) is to enter the route edit mode in SP and "drag" the errant intersection waypoint to coincide with the MetroGuide Intersection.

More Questions?  Comments?
Email to Joe Mehaffey