Using Points of Interest
The primary use of Points of Interest is to allow identification of different facilities, resources or functions within the built and natural environment.
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The primary use of Points of Interest is to allow identification of different facilities, resources or functions within the built and natural environment.
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Points of Interest data can be used within a table format, such as a spreadsheet or a database, to create gazetteer or list-type applications that allow people to search for a particular facility or resource. These applications make use of the attributes supplied for each feature and depend on the application system having a searching or querying facility that the customer can supply with search criteria.
To achieve the greatest possible value from the data, it is best viewed and analysed within a GIS. The combination of Points of Interest with topographic mapping gives context to the features, which cannot be derived from using it within a table or spreadsheet. Depending on the functionality of the GIS, it also provides the opportunity to:
Group the features into other subsets of data.
Combine the data with your own complementary datasets or with other Ordnance Survey products.
Customise the appearance of the Points of Interest features to suit your requirements. To get customers started, Ordnance Survey provides a suggested set of symbols, which are available from the Links and downloads section of the Points of Interest Product Support page on the OS website.
Extend the queries on the attributes by using a spatial element.
Points of Interest can be displayed within a GIS by using the Easting and Northing coordinates to display each feature’s geographic location as a point. The National Grid coordinates that accompany each feature allows it to be displayed as a point, in its correct position with regards to the National Grid and any other map based on the same reference system.
The simplest way to display the product is to render all points with a single colour and shape, as shown below. These can then be labelled with the classification code to understand what each point represents. By providing the context of the physical environment within which the Points of Interest features exist can add another dimension of meaning to the data. It allows a spatial understanding of the features to develop.
Points of Interest is completely customisable in terms of the way you choose to symbolise the points. The way in which the data appears on a screen is likely to be a combination of your wishes and the functionality of the system being used to display the points.
Most GIS have tools that provide options for rendering data on screen. Ordnance Survey has developed a set of symbols to use with the Points of Interest dataset, so that customers can render the data very quickly. This suggested set of symbols is available to view and download from the Links and downloads section of the Points of Interest Product Support page on the OS website.
Using a symbol set that makes use of Category level of classification means that the viewer can understand the information quickly. Comparing the figures above showing Points of Interest data rendered with a set of the supplied symbols, it is possible to get an idea of the range and type of features that are in this area without querying the attribution.
The symbol sets are supplied in:
Black and white bitmaps
Colour bitmaps
TrueType font
Refer to the Points of Interest symbology page for the colour symbols for the 52 available categories and their classes.
The real benefits of Points of Interest within a GIS can be seen when displaying the features over some backdrop mapping. This adds real-world context to the features. Points of Interest features are best used in combination with a large-scale product such as OS VectorMap Local, an example of which is used in the 1:3 000 image below. This allows both clarity and the ability to derive additional value from both products. A slightly smaller scale backdrop, such as OS VectorMap District, can also provide the necessary context. An example is shown below.
Whilst it is possible to view the data at any scale, the smaller the scale, the harder it is to see what real- world feature the point represents. There are problems of points either being difficult to distinguish from each other or, if they are set to enlarge as the map is zoomed out, they can disappear behind each other, as shown in the VectorMap District 1:10 000 image.
Classification provides structure to the data which helps when storing it. It provides a way of ordering the data, a means of visualising it, and a way for customers to find the features they are interested in quickly.
Points of Interest has its own classification scheme with each feature assigned to a Class within the system. The classification is central to the Points of Interest dataset as it provides a hierarchical structure to the data that makes it efficient to store in a computer system and easier to search. It also provides a means of subdividing the data so that customers can order only the features they want.
The classification was created by PointX. It is designed to be comprehensive, intuitive and easy to use. It provides the necessary level of detail to be useful and flexible without being so complex that it becomes difficult to use the product in applications. There are three levels of classification: Group, Category and Class.
Level 1 comprises nine Groups and provides the broadest categorisation. Level 2 comprises 52 Categories which are broken down into more than 600 Classes to form the third level of the classification scheme. This is the most specific level of classification. The full classification is given in a separate Classification Scheme page. Over the life of the product, some Classes have been changed, added or merged with other classes, which is why numbers in the tables are not sequential.
Having three levels of classification enables customers to make general searches. For example, at the Group level, education and health, specific searches at the Category level, such as primary, secondary and tertiary education, or specialist searches, such as special schools and colleges, at the Class level.
You can order Points of Interest at either the Group or the Category level. Features are allocated a classification based on either:
A classification provided by the original data supplier.
Where no classification is provided, PointX uses its experience and understanding of the dataset itself, or elements within it, to allocate a classification.
Classifications make it easy to use database or GIS tools to search, analyse and display features based on their Class. When used in conjunction with the attribution, it is possible to compile, for instance, a list of the names and addresses of estate agents within a given geographic area. In the figure below, the classification has been utilised to display all Bus Stops within an area using the classification code 10590732.
This breaks down as:
Group: 10 = Transport Category: 59 = Bus Transport Class: 0732 = Bus Stops
The structure of Points of Interest can be described as relational in nature. Each Group has one or more Categories below it. Each Category in turn has one or more Classes related to it. This type of structure is used extensively in database management technologies as it provides a way of storing the data in a way that reduces the amount of space required and speeds up the retrieval of information. Having this classification, therefore, provides an opportunity to store the data in an efficient way.
