Coventry Walks Coventry Walks Home Page & Main Index Map Index All Maps Page Google Search of this site

Map Source and Format

This page describes:

 

Source of Basic Maps Top

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

   eMapSite - details from http://www.emapsite.com/.  They are the same issue as available free from OS, but in a form much easier for me to use.  The licence is now the new OS free licence, and the charge from eMap is about 10% of what I use to pay for supply with the old OS licence!

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

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:

It is recommended that a paper street map is obtained to give detail support in finding names of roads, and the OS 1:25000 Explorer maps for countryside details.  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.

News May-2013 :
A new update of the base maps has yet again been supplied and incorporated.  This 2013 update adds a number of  updates to all maps.  Most are not very exciting, ranging from just moving the name of Ryton Bridge so that it does not cover the drainage channels joining the River Avon, throgh more schools with new buildings to the Humber Road area showing the major road diversions (replacing my version!) and a bit more detyail of the emerging new housing estate.

News Apr-2012
Improved detail visible on maps by changing compresion factor from 30 to 25.
  This gives significantly better definition, and the new Host site plus most users broadband speed should still give adequate response. Uupdate of base maps for Map12, Map22, Map 23 & Map31 completed, but full update of all not done since OS have only updated a few re-built schools, 2 minor road schemes giving access to emerging industrial developments & part of the housing development off Banner Lane.

News May-2011 :
A new update of the base maps has yet again been supplied and incorporated.  This 2011 update adds lots of  updates to all maps.  For example, a lot of the new buildings and roads are now shown, and many improvements have been made to naming roads. You will also notice that many schools are now named, many Post Offices which have closed are no longer shown, lots of new woods are added, lots of demolished factories are blank space and maybe all "back-entry" tracks are marked.  A few things are no longer shown, in particular all the "PH" symbols have been removed from all public houses in urban areas.  Overall the result is good.
As well as using the new updated base maps, I have used a bit higher contrast and darker settings so that it is a little bit easier to read some road names etc. (File size increase hardly noticeable).

News May-2009 :
A new update of the base maps was supplied and incorporated.  This 2009 update adds more minor roads and "back-entry" roads and updates to a few buildings and woods on Maps 11, 21, 31 & 41.  For example, the new housing estate off Browns Lane (Burlywood Close, etc.) has been added, and part of the main Jaguar plant building deleted, but nothing seems to have changed east of vertical OS grid line 30 (between H & I on ACW maps).   Very few changes have been made on other maps - the new road layout near site of "Canley Gates" has been added, but not anything else of significance.  I have however updated all maps, taking the opportunity to register each map and gridline more accurately (some were the odd pixel out in one or both directions, and on one map the horizontal grid lines were way out - all now line up "perfectly").  As well as using the new updated base maps, I have used a sharper still version so that it is a little bit easier to read some road names etc. (File size increase hardly noticeable - main advantage is when I produce special files from the masters at a much lower compression for detail studies).

News Apr-2008 :
A new update of the base maps was 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.

Sources of Path Information Top

The path information comes from many sources, including:

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.

 

The Map Grid Top

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:

 

Format of Master Files Top

Master files are in PaintShop Pro v.10 format.  A multi-layer format is used:

Most main paths are drawn 6 pixels wide in order to show clearly on screen or A4 print, but are reduced to 5, 4, 3 or 2 pixels in areas where finer detail is desirable. 

 

Format and Date of Published Files Top

Files are published as JPEG files.  Each is the same size as the Master file (2250x1500 pixels) and compressed at a factor of 25.  They are saved as mapnn.jpg file names, where nn is the number of the map.  This results in files range from about 700KB to about 1400KB (was 500KB to about 950KB before Apr-2012) 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:

The date at the top of the individual HTML print full map pages is the date printed for your own records, and the date at the bottom is the date the HTML page was last changed.  Sorry if this is confusing!  If you want to see the date a map last changed, try http://www.coventry-walks.org.uk/maps/index.html and look at date for mapnn.jpg (where nn is map number).  I tried finding a reliable way to get that date automatically displayed on the print full map page, but have failed so far (if anyone knows a method, please let me know).

See "Print Maps" Page for hints on printing.

 

Return to:

  


Coventry Walks Top

 

Goto Coventry Walks Home Page