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Topic |
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| Engor
Intermediate Member
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Calgary
838 Posts |
Posted - 05/30/2012 : 2:04 PM
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I'm planning a few summer trips based on Gillean Daffern's Kananaskis Country Trail Guide. Here and there the author uses grid references to pinpoint a place: peak 210395, ridge 147230 etc. I basically understand how GR works on topo maps, although it's not highly accurate on Gem Trek maps that I'm using. It was probably the only way to pinpoint location in a pre-computerized world.
I'm surprised the author doesn't provide latitude-longitude coordinates in a new edition of the book which are very handy for anyone who uses GoogleEarth or GPS. Is there an easy way I can convert GR numbers on GPS or GoogleEarth? |
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Langley, BC
Canada
1078 Posts |
Posted - 05/30/2012 : 2:46 PM
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There are some converters out there if you do a Google search.
There are also some open source software libraries if you want to automate the task for a large data set. |
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Calgary, Alberta
Canada
1186 Posts |
Posted - 05/30/2012 : 3:02 PM
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The online Atlas of Canada has a button that is called "Get Info From Map." It will provide you with the full UTM Coordinates, the topo map sheet and the latitude/longitude.
http://atlas.nrcan.gc.ca/site/english/maps/topo/map
If you know the full grid reference, you could punch it into one of the many converters available online. I found this one right away:
http://www.rcn.montana.edu/resources/tools/coordinates.aspx
There is an explanation on truncated grid references here:
http://bivouac.com/PgxPg.asp?PgxId=155
Personally I don't understand why you would need to do this. I just go to maps.google.com and right click and select "What's here." Tt will give you the latitude/longitude in the search box. I use this to create way points. |
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Hope, BC
Canada
7094 Posts |
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 | Dru
Mountain Grammar Police
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Sardonic sandbagging scoundrel, Cascade Climbers lobotomized spraymeister, space blanket flyer, new millennium vulgarian betaboy and friend to all squids
Climbing, a mountain
Canada
∞ Posts |
Posted - 05/30/2012 : 3:27 PM
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quote:
Originally posted by Engor
I'm planning a few summer trips based on Gillean Daffern's Kananaskis Country Trail Guide. Here and there the author uses grid references to pinpoint a place: peak 210395, ridge 147230 etc. I basically understand how GR works on topo maps, although it's not highly accurate on Gem Trek maps that I'm using. It was probably the only way to pinpoint location in a pre-computerized world.
I'm surprised the author doesn't provide latitude-longitude coordinates in a new edition of the book which are very handy for anyone who uses GoogleEarth or GPS. Is there an easy way I can convert GR numbers on GPS or GoogleEarth?
Most GPS can be set up to display either lat-long or UTM. So just switch your GPS over from lat-long to UTM and problem solved. |
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Calgary, Alberta
Canada
1186 Posts |
Posted - 05/30/2012 : 3:37 PM
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Oh, that reminds me, I used this website recently:
http://scribblemaps.com
It will allow you to draw kml/gpx routes over top of several layouts, including google maps topo, google maps satellite, open street map, etc.
Previously I would do this in Google Earth and convert the kml file to GPX using GPSBabel, but this website makes it so simple. |
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| Engor
Intermediate Member
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Calgary
838 Posts |
Posted - 05/30/2012 : 3:53 PM
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Thanks a lot folks, much appreciated! I'll study all links later tonight when I have more free time. Didn't know that a GPS can be set up to display UTM. Have to check the manual.
I tried to use a converter before that I found on-line but it moved me to Greece or Polynesia instead of Kananaskis Country. Not close enough  |
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| Engor
Intermediate Member
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Calgary
838 Posts |
Posted - 05/30/2012 : 8:26 PM
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Ok, I found out that a 6 digital grid reference is a truncated reference. To upload it to GPS one needs to know a full grid reference and that's whole science to translate a truncated reference to a full reference. That's just too complicated to waste my time learning. Thank you all.
Marko: I find GR coordinates useful when a book tells "at GRxxxxxx turn left", etc. It's especially useful for backcountry skiing but also other types of off-trail navigation.
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Kootenay Bud
2695 Posts |
Posted - 05/30/2012 : 9:25 PM
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quote:
Originally posted by Engor
Ok, I found out that a 6 digital grid reference is a truncated reference. To upload it to GPS one needs to know a full grid reference and that's whole science to translate a truncated reference to a full reference. That's just too complicated to waste my time learning. Thank you all.
Marko: I find GR coordinates useful when a book tells "at GRxxxxxx turn left", etc. It's especially useful for backcountry skiing but also other types of off-trail navigation.
It's not that difficult. Your GPS will actually need 7 digits for the easting and 7 digits for the northing. East goes before north. You can remember this using the ditty "go into the house and up the stairs." You can get the first two/three digits off the topo map. You will find the easting on the bottom left hand corner of the map - add a leading zero. The last two digits give accuracy to 10 metres for the second last digit and one metre for the last digit, which is irrelevant when you are navigating. Simply set those to 0 or 5 or whatever, it doesn't matter. The northing is also found on the left hand bottom corner of the map. Again, the trailing two digits are 10 and 1 metre accuracy and are basically irrelevant.
Sigh, what do they teach you kids in school today....
Easting and northing on 82F6, add a leading zero for the easting. |
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| Engor
Intermediate Member
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Calgary
838 Posts |
Posted - 05/30/2012 : 11:35 PM
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quote:
Originally posted by sandy
It's not that difficult.
Thanks sandy, I got it. With your help and with this quick guide:
http://maptools.com/UsingUTM/quickUTM.html
First two digits for the easting on your map are 04 and for the northing - 54, while the last 2 digits for both easting and northing can be random. I tried the converter and it works, no more Greece or Polynesia! Big thanks to you and to Marko for explaining it to me. I'm not that stupid after all, ha-ha  |
Edited by - Engor on 05/30/2012 11:36 PM |
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Canmore, AB
25 Posts |
Posted - 05/31/2012 : 07:04 AM
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The reason Gillean's references aren't that accurate on Gemtrek maps is that her references are using NAD 27 and Gemtrek is using NAD 83. This will cause an error of several hundred meters.To convert from NAD 27 to NAD 83: Northing add 221; Easting subtract 76.
Cheers
Rod Plasman |
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| Engor
Intermediate Member
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Calgary
838 Posts |
Posted - 05/31/2012 : 09:10 AM
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Thanks Rod. I couldn't get it why Gillean's references aren't very accurate on Gremtrek. If I understand you correctly, Peak 214404 should actually appear on Gemtrek as Peak 213406 and peak 237374 as 236376 and so on?
quote:
Originally posted by rplasman
The reason Gillean's references aren't that accurate on Gemtrek maps is that her references are using NAD 27 and Gemtrek is using NAD 83. This will cause an error of several hundred meters.To convert from NAD 27 to NAD 83: Northing add 221; Easting subtract 76.
Cheers
Rod Plasman
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Calgary, Alberta
Andorra
3787 Posts |
Posted - 06/01/2012 : 8:09 PM
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quote:
Originally posted by Engor
Thanks Rod. I couldn't get it why Gillean's references aren't very accurate on Gremtrek. If I understand you correctly, Peak 214404 should actually appear on Gemtrek as Peak 213406 and peak 237374 as 236376 and so on?
quote:
Originally posted by rplasman
The reason Gillean's references aren't that accurate on Gemtrek maps is that her references are using NAD 27 and Gemtrek is using NAD 83. This will cause an error of several hundred meters.To convert from NAD 27 to NAD 83: Northing add 221; Easting subtract 76.
Cheers
Rod Plasman
She also mentions both how GRs work, and relate to full grid references, and what datum she is using her her books, and to make sure to check the datums of the map you are using, and how to convert between datums in her introductions. :D
It's pretty simple to use once you try a couple times. I use maps as my primary navigational tool, and UTM for them, so I have my GPS permanently set to UTM. Note that you can also set up your GPS to use different datums, so if you're using an old map, you can set your GPS to NAD 27, and not have to convert. For recent maps, set your GPS to NAD 83 or WGS 84. They're functionally the same.
The newest Kananaskis Country Trail Guide doesn't actually mention the datums, so I am assuming she's updated to NAD 83 as well. One GR I checked quickly seemed within 100m of my estimate, but I didn't check a number of them to confirm. |
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Topic |
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Converting GR to Google Earth or GPS
