GIS Files 3: Adding real-world information

3.5: Structured GIS data is the key (5)

Polygon structured data

It is possible to create large-scale data that enables the identification of every single discrete parcel of land from spaghetti data. Many different GIS programs are able to automatically convert spaghetti data to polygon structured data by identifying every bit of space between linework. This means that the data is much more useful as it represents the real world in a much more realistic way. Again the data looks good, but now it makes much more sense and can be used easily straight off the peg for complex analysis.

Move the cursor over the map to see how you can pull up information about defined areas. You can't do this with spaghetti data!

Having converted all its paper maps to digital form, an almost equally daunting programme of work is now under way at Ordnance Survey to convert the point and line digital data into polygon structured data. The result of this re-engineering process will be known as OS MasterMap™ developed from the Digital National Framework™ (DNF™).

The decision to create OS MasterMap is the true measure of the impact of GIS on society. The needs of the country for map information are much more oriented to use in GIS (needs to be structured) than towards traditional visual renderings (doesn't need to be structured). OS MasterMap will encourage many more potential GIS applications to become possible, as users will be able to load information stored about actual objects or parcels of land into GIS in a consistent and comprehensive way.

We will be covering OS MasterMap in later chapters. In the meantime, we have a useful demo on our OS MasterMap page that will help explain the benefits of re-engineering our data.

Because so many companies and individuals use different types of geographical data, there is a need for consistency in storing attributes. This consistency means that a full range of information about objects can be brought together in a GIS and it is easier to share information. This is important, so a lot of effort goes towards defining standards for data structures. There are British, European and global standards bodies working very hard to make sure that all data providers and software vendors are working with data structured in a common way, so that the different datasets can be linked together. There will be much more about data standards in the Expert concepts chapter coming soon.

We have now finished chapter 3: Adding real-world information - the I is just as important; we hope you have found it useful.

The next chapter, chapter 4: Putting it all together as a system - the S in GIS, is now available.

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