science

Geographic Data Files

Geographic Data Files is a 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 Geographic Data Files rather than just read about it. In short: Geographic Data Files (GDF) is an interchange file format for geographic data. In contrast with generic GIS formats, GDF provides detailed rules for data capture and representation, and an extensive catalog of standard features, attributes and relationships.

Key takeaways

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

Reference excerpt

Geographic Data Files (GDF) is an interchange file format for geographic data. In contrast with generic GIS formats, GDF provides detailed rules for data capture and representation, and an extensive catalog of standard features, attributes and relationships. The most recent extension expanded applicability further towards pedestrian navigation, 3-D map rendering, and advanced driver-assistance systems (ADAS). GDF is commonly used for data interchange in many industries such as automotive navigation systems, fleet management, dispatch management, road traffic analysis, traffic management, and automatic vehicle location. Originated as a flat plain-text file, GDF is not intended to be used directly for any large scale geographic application and normally requires conversion into a more efficient format. Consumability has been increased with most-recent developments for XML and SQL renditions. The maps in GDF format are provided by many map vendors such as HERE, TomTom, Mapscape BV, GeoSmart, Automotive Navigation Data, AutoNavi and NavInfo.

Standardisation GDF is an international standard that is used to model, describe and transfer road networks and other geographic data. The standard was initially drawn up by CEN in co-operation with digital map providers, automotive and electronic equipment manufacturers. The outcome of these standardisation efforts (CEN GDF 3.0, or ENV14825:1996) has formed the major input to a global standard created by ISO/TC204 Sub Working group 3:

ISO GDF 4.0, formally referred to ISO14825:2004, now replaced by ISO GDF 5.0, formally referred to ISO14825:2011. However, despite the existence of an ISO GDF standard, the nature of model abstractions as well as semantic interpretations and proprietary content extensions lead to interoperability issues between flavors of GDF map products from different vendors. In practice the GDF files are not fully interchangeable due to vendor specific extensions. To this end, GDF5.0 provides major improvements in terms of extended meta data and flags for signalling implementation choices.

The new GDF5.0 The specifications of GDF5.0 were developed and compiled between 2001 and 2008, involving experts from Australia, Canada, Czech Republic, France, Germany, Japan, Republic of Korea, the Netherlands, and the United States of America. Extensive activities towards harmonization with ISO/TC211 standards were undertaken. GDF 5.0 was published in July 2011. Major GDF5.0 enhancements include UML model migration & refinements; harmonization with linear referencing and geo-spatial web standards; support for 3-D content and time coordinates; comprehensive character set and phonetic representations; and new XML and SQL based delivery formats.

Background and rationale of GDF standardization By the late 1980s, producers and users of digital road map data became increasingly aware of the need for a common data interchange standard. Lack of such a standard was seen as an impediment to the commercial growth and success of industries using such data. Before the advent of the Intelligent Transport Systems (ITS) industry, development of spatial data interchange standards was done mostly on a regional basis and not designed for the specialised requirements of road transport-related applications. In the 1990s, the GDF standard was instrumental in enabling the European business-to-business (B2B) market for in-vehicle navigation in that it provided interoperability for exchanging digital map data between map manufacturers and navigation system integrators. The GDF specifications provided a base for both the capturing of geographic content and the exchanging of it. Its original design foresaw a powerful, application-independent model, while its initial rendition as a standard specifically addressed the requirements for the richness of navigable map databases. Since then, GDF has evolved in terms of data modelling capabilities, broadened international applicability, expanded geographic domains, and diversified exchange formats. As a result, GDF covers a wide range of application domains and has been adapted to many geo-spatial technologies.

See also GeoIT file formats Geography Markup Language Keyhole Markup Language Global Positioning System (GPS) Map database management OGC standards

External links Link to GDF5.0 standard on ISO website

Worked examples

Example 1 — a first encounter with Geographic Data Files

Start with the simplest possible case. Write down what Geographic Data Files claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Geographic Data Files 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 Geographic Data Files 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 Geographic Data Files

In research: Geographic Data Files appears in 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 Geographic Data Files 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: Geographic Data Files is common in secondary-school and first-year university syllabi. It links to neighbouring topics GIS file formats, Navigation, Satellite navigation, so understanding it makes those chapters shorter.
In everyday life: Look for Geographic Data Files 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 Geographic Data Files in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Geographic Data Files 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 Geographic Data Files out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Geographic Data Files in simple terms?

Why does Geographic Data Files matter?

Because it connects several 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 Geographic Data Files?

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 Geographic Data Files.