Custom Route Extension API Developer's Guide

Overlay Map Matching

To overwrite an existing road link, or to connect a new road link to an existing road link, the coordinates in the overlay description get map matched. If the first and/or last coordinate shall snap onto an existing link, it must be within 5 meters tolerance from the existing link's shape.

An overlay geometry can also override a connected sequence of links. Simply provide sufficient shape points along this sequence of links. The Route Match Extension service is used to match the provided geometry against the map road links. Custom Route Extension API rejects coordinates if the Route Match Extension match confidence was too low.

Per default, the sequence order of the provided coordinates is NOT taken as driving direction. It gets matched in either direction onto one-ways.

However, if the sequence order of the shape points denotes the intended driving direction, this can be specified. Then, Custom Route Extension API avoides illegal paths (wrong direction through a one-way) and rejects the overlay submission if no probable legal match is possible.

Finally, sometimes the coordinates just denote a single path for the road, while the roads may actually be double digitized (dual carriage way) in the HERE map. To override both driving directions, the coordinates must be submitted twice (as two (2) operations), the second time with reverse sequence order.

Enforcing the coordinate sequence order to fit as legal driving direction onto the road can be specified for the whole overlay map submission by request parameter &point_order_obeys_one_ways=true. Alternatively, you can specify individually for each overlay operation, {"op":"override","point_order_obeys_one_ways":true