muninn.project Posted 23 April , 2013 Share Posted 23 April , 2013 Hello all, I've created an app to convert from British Trench Map coordinates to longitude and latitude, please let me know what you think. http://rdf.muninn-project.org/TrenchCoordinates.html?q=51b.A.4.a Rob. Link to comment Share on other sites More sharing options...
WhiteStarLine Posted 23 April , 2013 Share Posted 23 April , 2013 Hi Rob, I just tried this on Internet Explorer 10 and this is what I saw: Link to comment Share on other sites More sharing options...
CROONAERT Posted 24 April , 2013 Share Posted 24 April , 2013 Same here both on IE9 and Google Chrome. Link to comment Share on other sites More sharing options...
muninn.project Posted 24 April , 2013 Author Share Posted 24 April , 2013 Crap. So much for browser compatibility. Will poke at it tonight. Link to comment Share on other sites More sharing options...
muninn.project Posted 12 May , 2013 Author Share Posted 12 May , 2013 Sorry about that. Should be fixed now. Link to comment Share on other sites More sharing options...
WhiteStarLine Posted 12 May , 2013 Share Posted 12 May , 2013 Rob, just tried it in Internet Explorer 10 with exactly the same results as post #2. What browser are you testing in? Cheers, Bill Link to comment Share on other sites More sharing options...
muninn.project Posted 12 May , 2013 Author Share Posted 12 May , 2013 Tested on Firefox and safari, will need to get an IE browser to figure out what its doing. -Rob Link to comment Share on other sites More sharing options...
CROONAERT Posted 13 May , 2013 Share Posted 13 May , 2013 Seems to work OK on Chrome (but still not on IE9) Link to comment Share on other sites More sharing options...
alain dubois Posted 13 May , 2013 Share Posted 13 May , 2013 Hi, I just tried with my home location, according to the paper maps, I'm living in (shhh !).b.10.60.60, and if I want to be home with your app I must enter 75.50 . It works fine with Firefox 20. I don't think it is possible to make more accurate Regards Alain Link to comment Share on other sites More sharing options...
muninn.project Posted 14 May , 2013 Author Share Posted 14 May , 2013 Still working on getting it to work on Internet Explorer. It's a bit of a pain. -Rob Link to comment Share on other sites More sharing options...
WhiteStarLine Posted 21 May , 2013 Share Posted 21 May , 2013 Rob, this is incredibly useful and you deserve a lot of praise. I have just successfully tested this on my Android phone with Google Chrome and realised that anyone visiting a battlefield on the Western Front can use your app to find a British Trench Map reference on Google Maps and compare it with where they are standing. My test is for the von Richtofen crash site on my Huawei phone. Be interesting to compare the lat / lon result you get using the old observatory as your reference point, with my technique, which uses the grid origin at Charleroi. Well done ! Bill. PS - don't bother with IE. Link to comment Share on other sites More sharing options...
towisuk Posted 22 May , 2013 Share Posted 22 May , 2013 Nice one Rob...! a handy addition to our mapping software mate regards Tom Link to comment Share on other sites More sharing options...
b3rn Posted 23 May , 2013 Share Posted 23 May , 2013 Fantastic resource, thank you Rob. Link to comment Share on other sites More sharing options...
nigelcave Posted 23 May , 2013 Share Posted 23 May , 2013 Would an issue be magnetic deviation? Many congratulations on this - great work. Link to comment Share on other sites More sharing options...
johnreed Posted 23 May , 2013 Share Posted 23 May , 2013 If you are using Linesman the Lat/Long is already configured in WGS84. John Link to comment Share on other sites More sharing options...
muninn.project Posted 23 May , 2013 Author Share Posted 23 May , 2013 Rob, this is incredibly useful and you deserve a lot of praise. I have just successfully tested this on my Android phone with Google Chrome and realised that anyone visiting a battlefield on the Western Front can use your app to find a British Trench Map reference on Google Maps and compare it with where they are standing. My test is for the von Richtofen crash site on my Huawei phone. Be interesting to compare the lat / lon result you get using the old observatory as your reference point, with my technique, which uses the grid origin at Charleroi. Well done ! Bill. PS - don't bother with IE. I've never read anywhere about an origin at Charleroi, would you have a reference for that handy? I've started entering some old fortifications on the Open Historical Map... it should look great when it is finished. Rob Link to comment Share on other sites More sharing options...
muninn.project Posted 23 May , 2013 Author Share Posted 23 May , 2013 Would an issue be magnetic deviation? Many congratulations on this - great work. No. The surveyors learned quickly that magnetic compasses didn't work properly in the trenches owing to the high amount of metal lying around. The converter itself does not using magnetic headings so that should not be a problem. Rob Link to comment Share on other sites More sharing options...
WhiteStarLine Posted 23 May , 2013 Share Posted 23 May , 2013 Hi Rob, Once again, well done on your work. Have a look at the following threads, then it would be nice to chat to you and compare notes. Last September I toured the Western Front using a GPS, laptop and reverse engineered co-ordinates.: Navigating the Battlefields with Google Earth, GPS and British Trench http://1914-1918.invisionzone.com/forums/index.php?showtopic=185654 Converting Trench Map Positions to Google Maps http://1914-1918.invisionzone.com/forums/index.php?showtopic=178201 Finding a Trench Map Reference (newcomer reference) http://1914-1918.invisionzone.com/forums/index.php?showtopic=185768 Cheers, Bill Link to comment Share on other sites More sharing options...
muninn.project Posted 28 May , 2013 Author Share Posted 28 May , 2013 Bill, I've tried to reference the church steeple at 62d.j.28.d.70.50 and got about 100 yards of error using my calculator. This is using the delamber ellipsoid, a bonne projection, an origin computed by ngi and proj4 to convert the continous values. 100 yards is well within the error margin that the initial maps would have had in their original 'rough' projection and not bad considering that the distance is calculated from an origin that is about 200km away. 20 yards would have been the results expected of a local survey team and given that the church steeple is an official map reference point, your near dead-on results are to be expected. My theory so far is that the sheet edge alignments are not perfectly done to the Belgian grid: 62d is an after-the-fact British extension of the Belgian grid and they may be slightly off. We do know that the Trench Grid was an on-the-fly British decision reacting to a deep German advance, that none of the officially recorded Belgian origin coordinates make any sense and that my current origin was recalculated from the Belgian triangulation only. I suspect that what is happening is that the edges of the sheet and origin are slightly off globally. The contents of each sheet are dead on since they were re-surveyed several times during the war relative to local features while not necessarily worrying about the global location of the sheet edge. This would explain when my global method is off while your relative method is dead on. When I have a little bit more time, I will gather some map reference points and retry the triangulation using the trench maps without the Belgian triangulation and see what happens. Pretty impressive spreadsheet! Rob Link to comment Share on other sites More sharing options...
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