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Valhalla is an open source routing engine and accompanying libraries for use with OpenStreetMap data. Valhalla also includes tools like time+distance matrix computation and tour optimization (Traveling Salesman).

Overview

The are several key features that we hope can differentiate the Valhalla project from other routing and network analysis engines. They are:

• Open source software, on open source data with a very liberal license. Should allow for transparency in development, encourage contribution and community input, and foster use in other projects.
• Tiled hierarchical data structure. Should allow users to have a small memory footprint on memory constrained devices, enable offline routing, provide a means for regional extracts and partial updates.
• Dynamic, runtime costing of edges and vertices within the graph via a plugin architecture. Should allow for customization and alternate route generation.
• C++ based API. Should allow for cross compilation of the various pieces to enable routing on offline portable devices.
• A plugin based narrative and maneuver generation architecture. Should allow for generation that is customized either to the administrative area or to the target locale.
• Multi-modal and time-based routes. Should allow for mixing auto, pedestrian, bike and public transportation in the same route or setting a time by which one must arrive at a location.

Organization

The Valhalla organization is comprised of several repositories each responsible for a different function. The layout of the various repositories is as follows:

• Midgard - Basic geographic and geometric algorithms for use in the various other projects.
• Baldr - The base data structures for accessing and caching tiled route data.
• Sif - Library used in costing of graph nodes and edges. This can be used as input to loki and thor.
• Skadi - Library and service for accessing elevation data. This can be used as input to mjolnir or as a standalone service.
• Mjolnir - Tools for turning open data into Valhalla graph tiles.
• Loki - Library used to search graph tiles and correlate input locations to an entity within a tile. This correlated entity (edge or vertex) can be used as input to thor.
• Meili - Library used to for map-matching.
• Thor - Library used to generate a path through the graph tile hierarchy. This path and attribution along the path can be used as input to odin.
• Odin - Library used to generate maneuvers and narrative based on a path. This set of directions information can be used as input to tyr.
• Tyr - Service used to handle http requests for a route communicating with all of the other valhalla APIs. The service will format output from odin and support json (and eventually protocol buffer) output.
• conf - Runtime configuration files.
• Tools - A set command line tools that exercise bits of functionality from the libraries above and provide the basis for quality testing and performance benchmarking.
• Demos - A set of demos which allows interacting with the service and APIs.
• Chef - A chef cookbook demonstrating how to deploy the valhalla stack to a virtual machine (sample vagrant file included).

Documentation

Documentation for the Valhalla service provided through tyr as well as links to a variety of technical descriptions are provided within the valhalla-docs repository.