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nhopton
United Kingdom
102 Posts |
 Posted - 14/04/2011 : 16:42:40
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I've been experimenting with using Ordnance Survey OpenData DEMs with FWTools (free) and MM to make colour-shaded relief base maps. The method of working is to use FWTools to merge a number of OS (*.asc) DEMs to one file and to use this to make an elevation-coloured image and a hill-shaded image. Once the two layers (colour.ecw and shade.ecw) have been made the two images are blended in MM.
FWTools works from the command line, but I've tried to automate the process so that all that needs doing is to double-click on a few Windows batch files.
For testing the method of blending in MM I've put a couple of sample images on the web, they are for OS 100 km grid-square SO. You can download the hillshade image and the elevation-coloured image here (about 4 MB in total):
http://confound.me.uk/maps/colour.ecw
http://confound.me.uk/maps/shade.ecw
Load "colour.ecw" image into MM first, then load "shade.ecw". This will look horrible, but tap the spacebar, highlight the "shade" layer and adjust its transparency; i.e. move the "Blend" slider about three-quarters of the way to the left. Try experimenting with this setting. Also try experimenting with the colours of the "colour" layer, reducing the red and the green by 15 per cent, say.
Anyway, if any of this is of interest, I could get the method written-up and make the batch files available.
Regards, Nick.
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johnnew
United Kingdom
75 Posts |
Posted - 15/04/2011 : 13:45:50
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Thanks Nick. Anything to assist newbies to importing this OS Data and then manipulating it gratefully received.
I'm OK creating my own new basic maps in MM with simple lines and polygons based on imported raster maps but I'm struggling with use of the vector products from OS, simply because I don't use this aspect of MM often enough to get a real feel for what is going on.
Using available topographic height data from OS to produce some 3D modelled maps then adding coal seam sub-surface slope data would be of great benefit in mapping the area practical for Elizabethan mining (we know the max single shaft height used in this specific research locality was circa 90ft) but at the moment I don't really know where to start!
John New - Transport historian/researcher and Stephenson Locomotive Society Publicity Officer. |
Edited by - johnnew on 15/04/2011 13:49:44 |
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davesgrandad
United Kingdom
35 Posts |
Posted - 30/04/2011 : 17:30:07
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Hi Nick,
I have loaded these two layers, and I think both layers look good on their own. However, I have successfully blended them together as per your instructions, and they look great. I agree with johnnew that a write up of your method and batch files would be of great value to us all.
I think MM is a superb program and I am amazed by what it can do. However, learning how to make it do these clever things is a struggle for me, I must admit, so examples like these are invaluable to me. Thanks for all your hard work.
Best wishes to all,
David |
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Colour-shaded relief maps
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