New open-source dynamic location referencing method published by TomTom is “of great interest to the industry”

Date: 8/10/2009

Source: www.tomtom.com/, www.tisa.org/, www.ertico.com/

TomTom has launched an open-source, royalty-free dynamic location referencing method, called “OpenLR”. This is a new method, which joins the recently published ISO standard, “AGORA-C” approach, in this work area. The Traveller Information Services Association (TISA) says that “the open source, royalty free nature of the technology is of great interest to the industry”.

Why is this important?

In a summary presentation, TomTom describes the relevance of dynamic location referencing to the EC ITS Action Plan, and also as a requirement for the deployment of many ITS systems and services. It is hoped that OpenLR will facilitate the roll-out of dynamic location referencing in the mass market through:

• “The support of the leading market players
• An open and interoperable environment
• No/limited royalty fees
• No business limitations
• No technical restrictions for user groups and individual users”

The website continues:

“…This will facilitate new business opportunities in various areas of ITS, such as traffic information services, map content exchange and co-operative systems, where precise and compact dynamic location information is needed.”

What is location referencing?

Location data can be used for anything that needs to be accurately linked to a specific piece of or position on the road network. It can range from static road sign information to highly dynamic traffic and weather information, as well as safety-critical information.

Location referencing is the task of ensuring compatible referencing of locations when information is exchanged between different applications or systems with different geographic databases. There are two fundamental methods for location referencing defined in ISO 17572:2008 Parts 1-3, "Location Referencing for Geographic Databases":

• ISO 17572-2:2008 – The first method assumes common pre-coded tables, such as the European Traffic Message Channel (RDS-TMC).
• ISO 17572-2:2008 – The second method, Dynamic Location Referencing (DLR), varies in real-time. This was developed from the European “AGORA-C” proposal.

The amount of locations fit to be transferred is limited when using pre-coded locations. However, in dynamic location referencing every location in a map can be transferred.

TISA say that “dynamic location referencing is very important for travel information technologies such as TPEG, because it lets messages refer logically to a specific point in the transport network without pre-coding the location and with the capability to be correctly decoded in a terminal device that doesn't need to be using the same map”.

How does OpenLR work?

The new OpenLR method works by identifying several “location referencing points” (LRPs) and then joining these by the shortest path.

“Basic idea: a concatenation of a shortest path between LRPs covers the location completely. At least two LRP are needed for start and end of the location. Intermediate LRPs serve as a guide for the route calculation.”

Further information on the new approach, including a summary presentation and a technical document can be downloaded from www.tomtom.com/. The open-source code library is to be published soon.

Previous ITS Radar International location referencing articles can be found at www.itsradarinternational.info/.

ITS Radar International will continue to monitor developments in location referencing

Keywords: Geographic information, Standard