Map Source and Format

This page describes:

• Source of Basic Maps
• Sources of Path Information
• The Map Grid
• Format of Master Files
• Format and Date of Published Files

Source of Basic Maps

These maps are based on Ordnance Survey eSiteStreet/Street View .  The electronic data and the internet licence were obtained from:

   eMapSite - details from http://www.emapsite.com/  . 

These maps form a good basis for the footpath maps - key good points from my viewpoint are:

• More accurate than most
• Fairly up to date.  In line with latest published paper OS maps (but still missing some changes on the ground during the  last few years)
• Well presented.  Pleasant look, shows all roads and buildings well, useful amount of detailed identification of key features.
• All streets are clearly shown, but at a width which does not unduly reduce the green spaces of more interest for walks.
• Nevertheless simple, leading to good compression for adequate speed of download from the internet. 

The disadvantages of using these in preference to a street map such as the AA Street by Street or the Geographers A-Z maps are:

• Street names are often hard (or impossible) to read.  The AA and A-Z street maps increase the width of streets so that the names can be in larger print.
• No direct equivalent paper version is available to provide higher definition support versions to the same sheet layout and presentation.

News Apr-2008 :

A new update of the base maps has now been supplied and incorporated.  This is the first update since Apr-2005, but at last it has come!  Indeed I'm impressed that this version is now more up to date than the version OS have on their OpenSpace product, and has corrected a number of inaccuracies on the 2005 and earlier versions.  As well as using the new updated base maps, I have used a sharper version so that it is easier to read road names etc. - it does however increase file sizes a bit, which with additional data (e.g. "back-entry" roads to housed and more roads and buildings on new estates) and all now at compression factor of 30 will slow down loading, but with most users now on broadband I feel this is the correct current compromise.

It is recommended that a paper street map is obtained to give detail support in finding names of roads.  All these maps include a grid derived from the UK National grid, and most street maps show this as 500 metre squares lining up in position (but not the same grid letters/numbers) with the maps published on this site.

Sources of Path Information

The path information comes from many sources, including:

• Coventry City Council Brochures
• Notices displayed at some sites
• Coventry Evening Telegraph articles
• Warwickshire County Council latest draft Definitive Maps
• Any available maps showing footpaths
• Many paths were only determined from walking the route
• As the site gets used, from users of the maps reporting corrections and updates

Whatever the original source, I have tried to walk the route, and bring the data in line with what is actually on the ground now.  Where this has not been possible yet, I have an intention to walk the route as soon as possible.

The Map Grid

The map grid follows the popular notation for street plans of using letters from west to east, and numbers from north to south.  A continuous sequence across all maps (rather than starting again at A1 on each sheet) is used to ease navigation on the "All Maps" page.

The relation of the grid to the National Grid Reference System is illustrated on a small scale map overlayed with excel spreadsheet grid.  This also shows the relationship to the Warwickshire Definitive Map sheets, and to the Coventry boundary.  This is available in:

• JPEG format (457 KB) or
• HTML Format (linked to the JPEG version) or
• Word Format print file (linked to the JPEG version) or
• the basic Excel spreadsheet (25KB). 

Format of Master Files

Master files are in PaintShop Pro v.7 format.  A multi-layer format is used:

• The base raster layer is 50% sized copy of the files supplied by OS.  This reduces them to 500 pixels per kilometre, and each of the 12 maps to 2250x1500 pixels.
• Layer 2, a raster layer, is added to shade in 80% transparent green all "Green Open Space" areas.
• Layer 3, a raster layer,  is added in some cases to provide local update to the base map where it is needed to correctly show a path location.
• Layer 4, a vector layer, is added to provide the grid, grid letters/numbers, and Map Number.  This layer is 50% transparent so that features of the underlying map remain reasonably clear.
• The "described path" layer, a vector layer highlighting some of the circular routes described on this site.  This layer is 0% transparent, using Bright Yellow or Orange highlighting colours to show the route of named circular walks.  The different colours are used to distinguish between two walks which share part of the route.
• The Path layer, a vector layer, shows paths, path names, additional feature names associated with areas paths are in, or features seen along the paths.

Most paths are drawn 6 pixels wide in order to show clearly on screen or A4 print, but are reduced to 5, 4 or 3 pixels in areas where finer detail is desirable. 

Format and Date of Published Files

Files are published as JPEG files.  Each is the same size as the Master file (2250x1500 pixels) and compressed at a factor of 30.  They are saved as mapnn.jpg file names, where nn is the number of the map.  This results in files ranging from about 487KB to about 923KB (was 340KB to about 620KB before Apr-2008) depending on the amount of information present.

The size and compression chosen result in maps of reasonable detail, but keep the file size just about acceptable from the point of view of:

• Download times via broadband (or via a 56kb/s modem for a few)
• Display speed once downloaded to cache.  A reasonably fast PC (1GHz+) with a modern memory size (512MB+) can show the All Maps page with good response times.

See "Print Maps" Page for hints on printing.

Return to:

• Source of Basic Maps
• Sources of Path Information
• Format of Master Files
• Format of Published Files