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Latitude and longitude to East and North


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Steven P

Good Morning,

just wondering if anyone has anything that converts latitude and longitude to an Eastings and Northings grid? I found some online but when I converted them to LISP, double checked what I did, they didn't quite work (UK Ordnance survey grid would be brilliant but it doesn't matter that much).

 

I have a sports watch that records GPS positing in Lat and Long (you can also get a phone app and other devices to do the same), and want to overlay the routes it records into a map. I guess I could even use this for work by walking the route of a buried service and (given a decent accuracy) plot this to site plans, but for now this is personal use - and so the budget for paid software doesn't really exist. I have the list of points, just need the conversion now.

 

 

Thanks for any help

 

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If you are in the UK, then the Ordnance Survey have a spread sheet for free download called Projection and Transformation Calculations that can transform coordinates one by one.

 

However be warned that there is an offset between simple GPS Latitude and Longitude and Ordnance Survey Latitude and Longitude. To see this, go to Google Maps, and in Greenwich Park, 0° Longitude is about 100m from the Prime Meridian mark.

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Steven P

Thanks Eldon, I haven't found the OS excel sheet yet - off to look just now.

 

As for offsets that would be easy to spot assuming it is consistent it would show up when I am  checking

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The quickest way is to use CIV3D which supports lat long input, I have downloaded photos from a phone, with tracking on they store the gps co-ord in the jpg used ghostscript to pull it out then placed all the photos on a survey plan. 

 

If you know someone that has CIV3d it would be like 2-3 minutes to download, make a dwg and re-email back. I am in wrong time zone for you or could do. 

 

I found the excel straight away google "Projection and Transformation Calculations" what was very interesting was that the VBA code is exposed, most times with this sort of thing its password protected. So you could edit the sheet and make it do multiple lat longs. you could then do a column answer with pline as top line and cut and paste to autocad. I am not real good at VBA but some one else may do it for you.

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Steven P

Thanks BigAl, you mean I am gong to have to hit the Civil 3D button and not basic AutoCAD. I'll have to remember to do that then.....(mostly I don't need any civil stuff, haven't had the lobotomy yet, so just go with basic AutoCAD). I assumed I would need something extra. I'll check it out later today and then spend next week 'working' hard doing what I want to do.

 

 

As an update, I got the spreadsheet OK - very good and it gives all the info, and working through it, I had a bracket in the wrong place error in the calculation. My LISP matches the spreadsheet. I used to be good at VBA and even Javascript (which was what my example code is), but over time have forgotten most of it.

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Yeah Civ3D is a pain type toolspace.

 

image.png.088ed000122ea64637b16de7f5d95d2c.png

 

So you can see no Lat long you actually have to go in and add it as a style, and set your world zone, then its easy. 

 

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OMEGA-ThundeR

If you know the convertion math, it wouldn't be hard to write a lisp for it.   I found the math for our own (dutch) system and made an google maps interface to search for a place and get the RD-coördinates we use.  You can also just enter the Lat and Lon to get the RD coordinates.  Something other websites will also do.

Since i know the math it would be easy to write a lisp for the convertion (and there probably already be a ton of convertion lisps out there).

In case anyone was wondering, my tool can be found at http://geokaching.nl/ (it's dutch, but might be self explanatory.)

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