Landmark’s Historical map data is offered as black and white raster data. Raster data provides a map image where the map information is composed of a grid of pixels that can be displayed on a computer screen. The data provides a good quality map background and is geographically accurate. This allows a direct comparison to be made between the present and the past. Historical Map data can also be printed on a suitable printer.
•An extensive collection of nearly one million map tiles spanning from 1841 to 1992
•Each historical map will cover a 1km2 area
•Each map is scanned at a resolution of 300 or 200 dots per inch (dpi)
•These dpi’s optimise file size with quality resulting in clear images and manageable file sizes
•All the historical maps are produced as A3 PDF files or GIF files
•All the maps have been de-skewed as much as possible to align the maps north and south
•Each map is uniquely identified and four pairs of National Grid co-ordinates that define the corners of the map sheet are provided
Quality
If you are purchasing individual maps we recommend that you check the previews supplied for quality and suitability before purchasing your historical maps. The majority of historical mapping is in excellent condition resulting in clean line work and backgrounds. However, a number of factors affect the quality of the scanned image. For example ingrained dust on the maps, in a small proportion of cases, resulted in dark areas.
The paper of some maps has become slightly distorted, affecting the overall geometry of the map; this is especially the case with the full sheet 1:10 560 scale County Series maps. As a result, these maps are not perfect rectangles and once de-skewed there may be some loss of data and a less than perfect join when the maps are lined up. However, this category of maps is a small proportion of the total.
Plotted Scales
Landmark Historical maps are not plotted to their original scale when printed from the PDF or GIF files supplied. However, they will have the details of the originally plotted scale and grid references on them for reference.
Epochs
Historical map data is available for different time periods referred to as epochs. These epochs roughly equate to the first County Series survey, and subsequent revisions, and the first National Grid resurvey and subsequent sheet revisions. Not all areas will have mapping available for each epoch as the number of revisions for each county varies.