Calverton Reference Map
and the Historical Index.

The Calverton Records Project has already amassed a considerable amount of data. Keith Hope-Lang explains how a computer drawing program can be used to record the information on to a multi-layer reference map.

The Historical Index contains historical facts about the village - almost invariably these are located by reference to places, either buildings or fields. The purpose of the Reference Map is to show the location of all these places.

Why another map when the Ordnance Survey maps already have so much detail? Because the details stored in a computer map can be selected to be just what is wanted - information not even recorded on the Ordnance Survey map can be included whilst unwanted details on the Ordnance Survey map can be discarded and clutter avoided. The only penalty is the time involved in drawing the map on the computer but this is only done once and is a splendid opportunity to learn about the village topography.

There are two valuable features to computer maps. First is the concept of layers; two dimensional drawing programmes for computers allow drawings to be built up from layers superimposed one upon the other. The user specifies which layers should be visible at any one time. A large amount of information can be stored but the printed map avoids confusion by only using the layers of interest. At present the village map has 7 layers. More layers will be added as more historical information emerges. The second valuable feature of computer maps is that the information is recorded in vector form which allows one source map to be printed at any scale without loss of detail. An example of this is shown above. The Reference Map (below) has been printed at a small enough scale to show the entire parish yet a selected part of the map, such as Middle Weald, has then been printed at large enough scale to show the shapes of the houses.

(© Crown copyright. All rights reserved. Licence number AL100034117)

How accurate is the map? The fields, roads and rivers were taken from the 1:25000 Ordnance Survey map and transferred to the Reference Map using a 100m grid. When the entire parish is viewed the significant features such as corners of fields have probably mostly been inserted with an accuracy of not much worse than 10-20m. The house and garden details were taken from the 1:2500 Ordnance Survey maps; initially the houses were sometimes entered schematically as rectangles but these are now being amended to show the true shape of a house.

The house details can be inserted with an accuracy of 1-3m where this is needed. Bear in mind that the original purpose of the map was to show the location of the houses or fields featuring in the Historical Index but there is a growing need for the map to record information with greater accuracy than this original need.

As with the Historical Index, the Reference Map is available to any resident. The map has been drawn on Autosketch and exists as a .SKD file. Any part of the map can be printed to a page of A4 at any scale and with whichever layers the user wants. Any resident with a computer and a 2D drawing programme can have a copy of the map on disk; Autosketch is widely used so it is likely that a compatible format can be found between Autosketch's export formats and the import formats of other 2D drawing programmes. If anybody's research in the village reveals information that can be mapped then an appropriate layer can be added.

Keith Hope-Lang.

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Last updated 24th February 1998.