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PostPosted: 14 Sep 2015 14:44 
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Joined: 07 Sep 2015 19:22
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I want to import historical maps from maps.nls.uk. The site is not a tile server so I am looking for tools that can capture the maps and save them along with their geo information. Does transdem have any tools to do this or any code snippets that can convert lon and lat co-ordinates to the format needed for trf files. I have apps to download the map tile to a file but I will have to write the code to translate the co-ordinates to the right format. Hence the request for any existing tools and code snippets.

Mike


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PostPosted: 14 Sep 2015 16:27 
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Joined: 05 Jan 2011 16:45
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The TransDEM map tile client can access the NLS map provider.

Currently, four map sources have been configured in the sample settings for the "Historic UK" group. Two of them use Sabre Maps addresses and two point directly to NLS. Not sure whether Sabre Maps redirects to NLS, too.

The four maps are two different historic series of the 1:50,000 map, the only available 1:25,000 map and the rather new 1:10,000 map from around 1900 to 1910.

For this latest addition see viewtopic.php?p=1990#p1990

Note: This map has been added to the July 2015 edition of the sample settings.


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PostPosted: 16 Sep 2015 17:43 
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Joined: 07 Sep 2015 19:22
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Thanks for the link but I have already tried that Tile server and all the nls tile servers. There not enough detail on the tracks around Oxford.
The nls Maps of England and Wales 1890-1920 OS 25inch
maps.nls.uk/geo/explore/#zoom=19&lat=51.7781&lon=-1.2781&layer176 shows twin tracks will the tile servers just show a symbolic track
Nls maps of Great Britain 1892-1905 OS 25inch with layer=168 also shows twin tracks.
I wish to capture these maps instead of using a tile server.

Regards
Mike


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PostPosted: 17 Sep 2015 01:17 
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Joined: 30 Jan 2011 13:03
Posts: 170
G'day MikeBr,

...with all this talk about tile maps and providers, Mike, I almost forget (and it seems Roland has, too), that, as a last resort, depending upon the format of the files your "download application" supplies and if you have corner co-ordinates of those 'clippings', you could always MANUALLY geo-reference them, using the instructions supplied with TransDEM for that purpose. If the clip 'images' are all the same size, once two images are correctly geo-referenced, you can rely on the program's internal calculations to get the location of subsequent co-ordinates correct (once the first has been provided by you), which makes all subsequent geo-referencing go much faster. As each clipping is saved, once manual geo-referencig is completed, it will be saved as an image in *.png or *.tiff format (depending on your TransDEM settings) with an accompanying *.trf file for future use directly in TransDEM...

Jerker {:)}


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PostPosted: 17 Sep 2015 11:04 
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Joined: 05 Jan 2011 16:45
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Digitizing of the historic O/S 25 inch map is marked as work in progress by the NLS. The map tiles available so far are currently spread over several Map Tile servers. The NLS map browser has specific code to query them all at the moment and hopes to get sufficient non-empty replies. The TransDEM map tile client is of a more generic type and does not support multiple servers simultaneously. It also paints empty replies as black, unfortunately.

Nonetheless, as I find the 25 inch map most fascinating, it's already on my todo list.


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PostPosted: 17 Sep 2015 17:53 
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Joined: 07 Sep 2015 19:22
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Thanks for the input. Rather than manually geo-referencing each downloaded image, I want to automate it. Can anyone point me to some code that translate lat/lon to WGS84 format. With the translation code I can generate the trf file as I download the images.

Regards
Mike


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PostPosted: 18 Sep 2015 09:11 
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Joined: 05 Jan 2011 16:45
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MikeBr wrote:
Can anyone point me to some code that translate lat/lon to WGS84 format.
That's actually rather straightforward because manual (or more precisely semi-manual) georeferencing is built into TransDEM.

Go through tutorial 1 in the TransDEM main manual, from page 118 in the current edition, to get the idea and some hands-on experience.

Then take your browser screenshot (Alt+Print), preferably in full screen mode, paste into TransDEM (Ctrl+V), draw a rectangular mask to get rid of non-map margins. Save the mask for later use (Ctrl+M, or Tools | Edit Rectangular Mask) by assigning a name to it. Crop to the mask (Shift+C).

In the View menu set the coordinate system to OSGB36. Start georeferencing as in the tutorial. Find an identifiable map point in the browser map. Check the coordinate values, browser bottom right. You will need the second row. These are the full O/S grid coordinates. Locate the same point in TransDEM for coordinate input. Enter the values. Repeat for point 2 and 3. Proceed as in the tutorial.

For the next map screenshot retrieve the clipping mask with Shift+M (provided you did not modify dimensions).

Needs a bit of practice but there are shortcut keys for most steps to minimize mouse movement. Best with two monitors.

25 inch on top of 6 inch map (proof of concept):
Image


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PostPosted: 29 Sep 2015 18:33 
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Joined: 05 Jan 2011 16:45
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Support for the 25 inch map will be included in TransDEM 2.6, see here.


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PostPosted: 30 Sep 2015 21:28 
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Joined: 07 Sep 2015 19:22
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Version 2.6 sounds great, when will it be available


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PostPosted: 01 Oct 2015 08:32 
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Joined: 05 Jan 2011 16:45
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My idea is before the end of the year but I don't make promises.


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