[mkgmap-dev] Routing Algorithm of Garmin

Sat Aug 16 13:46:54 BST 2014

Hi Bernhard,

Garmin has 2 version of routing algorithm, older and newer. Older is 
used by Mapsource, older nuvi, probably by outdoor devices. Newer 
algorithm is used by BaseCamp and last 2-3 generations of nuvi.

Newer algorithm is designed for speed of calculation rather than quality 
of results. Finding fastest way is based on road classes. At longer 
distances device uses only class 4 roads ignoring shortcuts with lower 
class. That's why you can optimize route manually.

Older algorithm is more precise, it can use lower class roads, when 
class 4 roads are missing. Calculations are longer. But probably you 
still can find better route manually.

-- 
Best regards,
Andrzej