WGS84 -> OSGB and back

[Guest dna]

Newbie question (but can't find it in a fAQ anywhere).

 

Has anyone come across an easy way of converting WGS84 to OSGB. When we're trying to decide on a cache to go and hunt for, we tend to want to get an approximate location first so that we can work out where to park, which path to take (if it's part of a longer walk) etc. especially if we're in a part of the country we don't know.

 

The easiest way (for us) seems to be to grab a rough (eg 6 fig) OS ref and look it up on the appropriate 1:50,000 map, but I've been searching for simple ways of doing that conversion. Ideally it would be great if, for UK caches, the "convert to NAD27 or UTM" feature also allowed "convert to OSGB" but I'm not holding my breath.

 

In the interim, does anyone have a nice simple WGS84 - OSGB converter without me having to keep resetting the GPS.

 

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DNA

(Deb 'n Andy)

[Guest Moss Trooper]

Welcome Friends.

 

Two ways.. one.. Use your GPS.. poke it in as one datum co-ords etc.. then convert.

 

Download GPS Utility .. www.gpsu.co.uk enter the waypoint in OSGB an convert to WGS 84 lat/long. This prog is shareware and is good for uploading an downloading to GPS, allows routes, tracks and you can overlay maps as well.

 

The important bit to remember is to make sure u change the datum as well as the co-ordinates. Other wise yer can have a cache 100 meters away from where folks is lookin.

 

No doubt others will chuck in there 2 pennyworth.. )

 

Moss de Boss... Sorts.

[Guest dna]

Excuse the indulgence of replying to my own post but I've just looked through some of the other threads and found Rob & Lisa's page o' caches at

www.WOOKIE.demon.co.uk/geocache

 

(replace the "WOOKIE" with "cookie" to get over Groundspeak's silly content checking)

 

which has everything I wanted.

 

Thank you !

 

[This message has been edited by dna (edited 04 February 2002).]

[Guest SeeMim]

You can convert WGS84 to OS at http://www.gps.gov.uk/login.asp you need to register, but tht's free at present.

SeeMim

[Guest jeremyp]

Actually if anybody can point me at a web site with the algorithm on it I'd be grateful as I am writing an Open Source GPS utility for use with not just Windows but Linux and MacIntoshes too.

 

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Why use one word when two polysyllabic agglomerates will do?

[Guest Lisa]

quote:

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Actually if anybody can point me at a web site with the algorithm on it I'd be grateful as I am writing an Open Source GPS utility for use with not just Windows but Linux and MacIntoshes too.

---

 

This PDF gives you the algorithm:

http://www.gps.gov.uk/additionalInfo/images/A%20guide%20to%20coord.pdf

but it's a pretty convoluted conversion. There's also an excel spreadsheet here:

http://www.bangor.ac.uk/is/iss025/osgb.xls

that implements the algorithms.

 

Cheers,

Rob.

[Guest jeremyp]

The PDF I've seen before, but it doesn't give all the necessary info e.g. the positions of the ellipsoids relative to each other.

 

The Excel spreadsheet looks like it'll have what I need. The only problem is my version of Excel refuses to read the macros - they're in old style Excel macro language.

 

Anyway, when I have some code, I'll post it here for people to test.

 

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Why use one word when two polysyllabic agglomerates will do?

[Guest chris n maria]

You could try:

http://www.gps.gov.uk/guide6.asp

 

but I can't understand any of it - so good luck!

[Guest chris n maria]

I've had a look at the spreadsheet and it works OK on Excel 2000. The Macros arn't the old style they are VBA code - you can see how it works and everything.

 

If you are using XL2000 then it is a fair chance that you have Tools..Macros..Security Set to high which stops all macros running. Change it to medium & you should be OK.

 

I currently have a spreadsheet - available to anyone who mails me - that does the conversions between all the latitude/longitude formats and WGS84. I'll see if I can extend it to do OSG as well. If I can, I'll let you all know here.

 

Cheers

Chris

(Chris@fabalou.com)

[Guest Lisa]

Actually here is a better spreadsheet (and it is in Excel 97 format so you may have better luck). It is based on the algorithms in the PDF and uses Helmert transformations instead of Molodensky which are more accurate.

 

http://www.gps.gov.uk/additionalInfo/images/ProjectionandTransformationCalculations.xls

 

Cheers,

Rob.

[Guest jeremyp]

quote:

---

Originally posted by Rob & Lisa:

Actually here is a better spreadsheet (and it is in Excel 97 format so you may have better luck).

Cheers,

Rob.

---

 

That's great. It has a table with exactly the missing information from the PDF in it. Now to start hacking!

 

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Why use one word when two polysyllabic agglomerates will do?

[Guest LazyLeopard]

quote:

---

Has anyone come across an easy way of converting WGS84 to OSGB.

---

 

I usually follow the map link on the cache page to see roughly where I'm going to have to get to.

 

Some map sites also have co-ordinate conversion facilities. Try www.streetmap.co.uk, which has a link that'll convert between postcode, Lat/Long (which is WGS84), OS grid and Landranger. The main complaint I have with that site is that it takes Lat/Long input as d.ddd,d.ddd (decimal degrees, positive north and east) but its output is Cd:mm:ss (where C is N/S or E/W as appropriate)

 

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Purrs... LazyLeopard

[Guest chris n maria]

I now have available (to anyone who mails me requesting it) a spreadsheet that does the conversions from and to:

All three Latitude and Longitude formats

UTM(WGS84)

 

And now as of the current version (3.0) it converts from all the above formats in to UK Grid references.

 

It does not use any macro code so should work on Palm & CE machines.

It is completely free to use and always will be.

 

Mail Me: Chris@fabalou.com if you would like a copy.

 

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~~~~~

Chris

[benhup]

For converting between GPS WGS84, UK OSGB36, Dutch RD and UTM, you can use this online tool:

http://www.benhup.com/?mf=tools&sf=convert-coordinates

Best regards,

Ben

[+Ranger Roo]

The OS grid reference is listed on the cache page right under the Lat/Long coordinates

[team tisri]

For converting between GPS WGS84, UK OSGB36, Dutch RD and UTM, you can use this online tool:

http://www.benhup.com/?mf=tools&sf=convert-coordinates

Best regards,

Ben

 

Thread necro of the decade!

 

[DaveJFT]

Folks

 

Does anyone know of an Android app that can do this?

 

I had a 2 part cache this weekend: the first part of which gave OSGB coordinates to the second part. My GPS can only use WGS84. I tried to use online sites to convert but where I was I could only get a very flakey 'G' signal on my phone so it took forever and several attempts so I need to find a way of doing this offline.

 

Many thanks!

[+MartyBartfast]

Folks

 

Does anyone know of an Android app that can do this?

 

I had a 2 part cache this weekend: the first part of which gave OSGB coordinates to the second part. My GPS can only use WGS84. I tried to use online sites to convert but where I was I could only get a very flakey 'G' signal on my phone so it took forever and several attempts so I need to find a way of doing this offline.

 

Many thanks!

 

Geocache Calculator : https://play.google.com/store/apps/details?id=eisbehr.gcc

It does LOADS of stuff, including converting co-ords, and has some good tools for solving puzzles.

[+Wild-Skye]

Folks

 

Does anyone know of an Android app that can do this?

 

I had a 2 part cache this weekend: the first part of which gave OSGB coordinates to the second part. My GPS can only use WGS84.

What GPSr are you using? Most - even basic ones - have settings to change from lat/long to OSGB