Base Maps, Data and GPS
This section provides reference sources for base maps and raw data that can be loaded into a GIS. The Global Positioning System (GPS) is included as it forms one key element of the map data, i.e. locations that are identified with exact geographic co-ordinates (georeferenced).
It is important to know that in the context of GIS, a 'digital map' is one that has location data built in as co-ordinates. They are referred to as 'intelligent' maps because they allow for accurate positions to be given and for measurements to be made. Other maps such as scanned images can be used in GIS programs, but the tools for location and measurement will not work, unless co-ordinates are given to the map. Vertical air photos and satellite images can also be used in digital form with co-ordinates. Some GIS programs can be bought with a range of maps and other images, such as the Digital Worlds and Memory Map programs.
Raw data in a table, either in a spreadsheet or data base, can be linked to specific lines, areas or points on a map. This is what makes it possible for the data to be mapped with quantitative symbols or shading.
This website provides access to raster OS maps at different scales. The site is searchable by a place name or post code.
Mastermaps are the digital maps that are commonly used in GIS programs. They replace the former Landline series of maps.
These are digital maps that can be loaded into a GIS program. The file formats that programs with GIS functions can accept, however, can differ. They also save map files in their own formats.
This web site is a source of data that can be used in a GIS. The Neighbourhood section gives access to statistical data about local areas that can be searched by name or post code. Data can be downloaded in .csv format, i.e. a common format that can be converted for use in any spreadsheet such as Excel. Data from a spreadsheet can be copied and pasted into a GIS, attaching it to lines, areas or points on a map layer.
Ordnance Survey website: Raster and Vector maps
The GIS Files section of the OS web site provides information about different aspects of GIS. Section 1 provides text and diagrams that clearly explain the differences between these two types of maps.
Ordnance Survey website: Access to digital maps
This document lists the different types of maps that can be made available for free to most schools (state schools) through the school's LEA. The main types of maps come in a series called MasterMaps. Layers of map data can be downloaded from the OS web site.
Ordnance Survey: The Global Positioning System (GPS)
This part of the Ordnance Survey website gives an introduction to the Global Positioning System, explaining how it works and the importance of georeferencing.
