Thread: Great Britain Discoverer National Parks 1:25k Lake District-Brecon Beacons-Peak District

The map is blurry because it is a rastermap. To explain the difference between a vectormap and a rastermap:

If you want to draw a line in a vectormap the you "draw" a geometric point from which the line starts and a geometric point where the line ends. And if you enlarge the map the points and the line still remain geometric points and lines which have no width and are always clean points and lines. The size of the mapfile in bits is very small and it does not matter if the map covers 5 meter by 5 meter or 50 kilometer by 50 kilometer. A second line: mapfile is double in bits. A map with say 37 lines is 37 times as big as a map with one line.

If you draw a point in a rastermap you have a raster and you must fill one field of the raster with black colour and all the other fields with white colour. From some distance you see a black point in a white field. To draw a line you must fill many many fields of the raster which give - looked at from some distance - a line. If you get closer you see the "fields" and therefore a rastermap looks blurry if you enlarge it too much. The size of the mapfile in bits increases dramatically if the map covers a bigger area as you need more fields of the raster or if you use a more fine raster. A map with say 37 lines instead of one line is only a little big bigger than a map with one line for only the information "white" is exchanged against the information "black" for the fields of the raster where the lines are.