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How to use OS VectorMap™ District (ESRI® Shape format) https://forum.transdem.de/viewtopic.php?f=6&t=32 |
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Author: | geophil [ 01 Feb 2011 20:09 ] |
Post subject: | How to use OS VectorMap™ District (ESRI® Shape format) |
Requires TransDEM 2.1.2 or higher. British Ordnance Survey offers a variety of map data with their Open Data initiative: http://www.ordnancesurvey.co.uk/oswebsite/opendata/ Among them is OS VectorMap™ District, a vector map at a nominal scale of 1:25000. We will abbreviate it to VMD. Data is packed into tiles of 10 x 10 km and structured by O/S 100 x 100 km grid squares. To find the grid square, an overview map should be loaded in TransDEM and the coordinate system switched to OSGB36. Grid square codes are shown in the TransDEM status bar, if the View | Show grid square option is activated. The numerical digits in the file name indicate the 10 km tile in square coordinates, the first digit for the easting, the second digit for the northing. The following is an example on processing this data. We will look at an area in the Pennines, Lancashire and West Yorkshire, which I have used before. It's the home of the Rochdale and the Leeds & Liverpool canals. We will find railways, too, but I may be a bit distracted here, when dealing with this part of England.
Looking closer at the vector data we notice a number of gaps: At first glance it looks like a quality issue, but it is not. The purpose of this vectors is to provide the data for drawing a map, not for navigating track. Adding an ortho image reveals the nature of the gaps: overbridges. Quite helpful, when working on the route in Trainz Surveyor later. The picture also shows the Leeds & Liverpool Canal meandering on its way through Burnley with the modern times motorway aqueduct at the top edge. At the other end of town you would find the Burnley Embankment, one the engineering marvels of the Canal Age. |
Author: | PFX72 [ 09 Feb 2011 23:02 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
Hi geophil. Having upgraded my TransDEM, to 2.1.2, I abandoned my route and started again using the O/S track vectors. What an improvement it's made over hand drawing a route. Thanks for the update. One problem I have encountered however, is that when I try to acquire maptiles for the route, I get a message telling me the 'Path is too Complex'. I've found that I can do a work around by using a manually added simple route but it does entail a lot of extra work. It's still a fantastic piece of software though.. PFX |
Author: | Jerker [ 10 Feb 2011 12:10 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
G'day PFA72, You will also find that you can 'work around' the "too complex" issue by 'editing' the 'complex' route, dividing it into smaller portions (with a little overlap) and getting the maps in 'bits' along these portions as you are now... Jerker {:)} |
Author: | geophil [ 10 Feb 2011 14:06 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
In this case I assume it may have to do with the numerous gaps in the vectors. This makes the vector data overly complex for the purpose of acquiring map clippings along a path. I suggest to simply draw a few strokes which roughly resemble the course of the line, for setting the path to access the Map Tile server. Use an extra layer for this by opening the TransDEM Simple Route Editor with the "Simple Route Editor, New Route" command or Ctrl+Shift+E (not on the toolbar). |
Author: | PFX72 [ 11 Feb 2011 21:14 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
I did just that and success. Thanks again geophil. |
Author: | eddieprice [ 27 Dec 2013 12:44 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
I found this tutorial interesting after finding the OS web site. I have used the Landform data to produce an elevation image. I then used the Vector Map data to place rail track. For the rest of the detail, roads, rivers, etc. I scanned a Landranger map and added the raster image, after georeferencing it. However, after adding the raster image, the track and elevation data do not line up with the raster image. Is there any way of establishing a reference position on the elevation and track image which could be used to establish a similar position on the raster image? |
Author: | geophil [ 27 Dec 2013 14:14 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
Apparently something went wrong with geo-referencing. You probably used the 3+1 point method. Coordinates on O/S maps are OSGB36, but TransDEM uses UTM/WGS84. That includes geographic coordinates, i.e. latitude and longitude. N56° W003° for instance would point to different locations in OSGB36 or UTM/WGS84, probably around 150m apart. The easiest way to obtain pre-georeferenced O/S Landranger and Explorer maps for TransDEM is the Microsoft Map Tile service, called by its original name "MS Virtual Earth" in TransDEM. Select Tile Type "Other 1". Zoom levels up to 14 produce the 1:50,000 Landranger map, zoom level 15 and higher the 1:25,000 Explorer map. |
Author: | eddieprice [ 28 Dec 2013 12:23 ] |
Post subject: | Re: How to use OS VectorMap™ District (ESRI® Shape format) |
Thanks Geophil. You were right, I had entered the wrong co-ordinates during georeferencing. With the correct values the difference was a few metres. I must have a look at the Map Tile service. EddiePrice |
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