computer science

OpenLR

OpenLR is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand OpenLR rather than just read about it. In short: OpenLR is a royalty-free open standard for "procedures and formats for the encoding, transmission, and decoding of local data irrespective of the map" developed by TomTom. Specification The format allows locations localised on one map to be found on another map to which the data have been transferred.

Key takeaways

OpenLR belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OpenLR to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OpenLR from memory before moving on to harder problems.

Reference excerpt

OpenLR is a royalty-free open standard for "procedures and formats for the encoding, transmission, and decoding of local data irrespective of the map" developed by TomTom.

Specification The format allows locations localised on one map to be found on another map to which the data have been transferred. OpenLR requires that the coordinates are specified in the WGS 84 format and that route links are given in metres. Also, all routes need to be assigned to a "functional road class". The specification is described in a white paper licensed under a Creative Commons license. Additionally, TomTom has published an open-source library for the format under the Apache license.

TISA adaptations and ISO standard The Traveller Information Services Association (TISA) adopted OpenLR for the TPEG2 standard, albeit with some modifications to align it with the conventions and principles of TPEG2. While functionally equivalent to the TomTom specification, the TISA adaptation differs in the XML structure and some field names (e.g. by use of the term properties where TomTom uses attributes); the binary format is also different. TISA’s version of the specification was subsequently adopted as ISO 21219-22:2017.

Datex2 OpenLR is one of multiple location referencing methods supported by Datex2. While functionally equivalent, the Datex2 adaptation of the format is not interoperable with either the TomTom or the TISA/ISO specification at the XML level.

See also Traffic Message Channel GPS Point of Interest

References

External links OpenLR - Open, Compact and Royalty-free Dynamic Location Referencing Archived 2020-04-16 at the Wayback Machine

Worked examples

Example 1 — a first encounter with OpenLR

Start with the simplest possible case. Write down what OpenLR claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to OpenLR before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about OpenLR ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of OpenLR

In research: OpenLR appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses OpenLR in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: OpenLR is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computing stubs, GIS vector file formats, Geographic data and information, so understanding it makes those chapters shorter.
In everyday life: Look for OpenLR outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study OpenLR in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OpenLR means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain OpenLR out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OpenLR in simple terms?

OpenLR is a royalty-free open standard for "procedures and formats for the encoding, transmission, and decoding of local data irrespective of the map" developed by TomTom. Specification The format allows locations localised on one map to be found on another map to which the data have been transferr…

Why does OpenLR matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study OpenLR?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on OpenLR.