Location Referencing at HERE

HERE is a company specialized in mapping technologies, location data, and related automotive services to individuals and companies. It is majority-owned by a consortium of German automotive companies, making it a key player for vehicle automation technology.

The Location Library is one of the components offered by their platform, allowing Java and Scala developers to access data related to the road network and other properties. It also offers utilities to navigate the through graph abstractions and algorithms to map match GPS traces to the road network.

The library needed to offer support for location referencing. A location reference describes a location. That can be a particular point, shape, or part of the road network. More specifically, the library needed to support TPEG2, a data protocol used for traffic and travel related information, and what the standard calls “applications”, which are containers that carry specific content. Among them OpenLR (OLR) and TMC. While TMC relies on predefined location tables to refer to road segments, OLR defines rules for generating map-independent location references that use on a collection of waypoints and other detailed information for each of those points, and rely on map matching to decode the references.

A linear reference using OLR

We added support for TPEG2 TMC and OpenLR location referencing to the HERE Location Library, together with examples and the documentation that is provided to users of the library.

While doing so, we collaborated with internal teams to ensure alignment with the existing Location Library, and delivered presentations to pilot customers to validate the solution direction.

To support our development and the validation of the implementation, we created tools that could automatically run hundreds of test cases against expected results, and that produced GeoJSON-based map visualizations to provide us with better understanding of these results and potential improvements.

Using Flexivis to visualize selectable map content

Some of the technical aspects of our work included:

• Dealt with TMC location tables and TPEG2 standard documentation to produce specification-compliant code.
• A custom code generator to create XML and binary encoders and decoders for the TPEG2 protocol and its application types.
• High quality Java and Scala APIs to encode and decode the location references and properly integrate with the Location Library ecosystem.
• A GeoJSON library to easily create visualizations of any map-related content.
• A command line tool that renders GeoJSON files and the HERE map tiles to images. This tool is used to automatically generate examples and embedded the resulting images on the library’s documentation.
• We later created Flexivis, a flexible visualisation tool that can render different types of data and has a light syntax to organize how is this information presented.