Configuration

To launch a Meili service or instantiate a MapMatcherFactor, you need to pass it the Valhalla configuration file, which holds all configurations for Meili at the node meili.

Map Matching Parameters

The map matching parameters control accuracy and performance of the map matching process. All transport mode nodes (auto, pedestrian, bicycle, multimodal) can hold its own settings of these parameters, otherwise the setting in default node will be used.

All transport modes can specify following parameters:

Parameters Description Default
sigma_ z A non-negative value to specify the GPS accuracy (the variance of the normal distribution) of an incoming GPS sequence. It is also used to weight emission costs of measurements. 4.07
beta A non-negative emprical value to weight the transition cost of two successive candidates. 3
max_route_distance_factor A non-negative value used to limit the routing search range which is the distance to next measurement multiplied by this factor. 5
max_route_time_factor A non-negative value used to limit the routing search range which is the time to next measurement multiplied by this factor. 5
breakage_distance A non-negative value. If two successive measurements are far than this distance, then connectivity in between will not be considered. 2000 (meters)
interpolation_distance If two successive measurements are closer than this distance, then the later one will be interpolated into the matched route. 10 (meters)
search_radius A non-negative value to specify the search radius (in meters) within which to search road candidates for each measurement. 50 (meters)
max_search_radius Specify the upper bound of search_radius 100 (meters)
turn_penalty_factor A non-negative value to penalize turns from one road segment to next. 0 (meters)

Service Parameters

The service parameters below are only used in the Meili service:

Parameters Description Default
mode Specify the default transport mode. multimodal
customizable Specify which parameters are allowed to be customized by URL query parameters. ["mode", "search_radius"]
verbose Control verbose output for debugging. false