Fire trail coordinate format?

[Yurt]

In my area (NNE Sydney) I've noticed new signs on the fire trails. They have what looks to be coordinates on them but in a different format that looks like UTM. An example:
321950E 6268624N

I've found a report with similar notation and the heading "AMG:56H" before the coordinates.

How are these converted? I've put them into a converter but get weird results using the 56H.

Anyone?

[caughtatwork]

http://maps.google.com.au/maps?f=q&sour ... 8&t=h&z=16

http://home.hiwaay.net/~taylorc/toolbox ... eoutm.html
Pick the southern hemisphere.

[Gowza]

Ok so I see these links... and I see these results.... but can I beg an explanation of how they have come about? Pleeeeease?

[Gowza]

Hahaha don't mind me..... clearly if I look at the second link it makes perfect sense! Eeeek

[tronador]

Yes they are grid references which are used with topographic maps. Very easy to pin point your location with these, without the aid of a GPS. When plotting, the 56H is not used when plotting. The 56H is a UTM zone, which includes Sydney.
http://www.icsm.gov.au/mapping/map_projections.html
You can see the zones here.

[Kerry]

In my area (NNE Sydney) I've noticed new signs on the fire trails. They have what looks to be coordinates on them but in a different format that looks like UTM. An example:
321950E 6268624N

I've found a report with similar notation and the heading "AMG:56H" before the coordinates.

How are these converted? I've put them into a converter but get weird results using the 56H.

Anyone?

Converted to what? Lat/Long maybe? Why not simply change the GPS format and input them direct?

However this raises several other questions. Is there any other infomation with these coordinates? To directly input or to convert these, is a zone number listed with these coords or are you expected to know all about this? Next how about a datum or does everybody today expect things to be MGA (as opposed and different to "AMG:56H")

Actually noticed a commonwealth organisation last week still listing and requiring positions in AGD66, yet many assume AGD/AMG no longer is used.

[Yurt]

Thanks for the help. I was just curious about them plus the report I was looking mentioned an old cemetery and other features nearby but expressed the locations in this format. Was just trying to see where they were on Google Earth. The fire trail numbers have no real use for a geocacher as far as I can see except maybe for mystery or multi caches.

I used one online conversion (not the one c@w posted) and it was close with the longitude but about 13 degrees out with the latitude. There must have been another button to click as it may have assumed northern hemisphere as you say.

Interesting in the report I mentioned that one of the features had the notation "Location: unable to obtain signal." Sounds like a good spot for a nasty cache!

[tronador]

Converted to what? Lat/Long maybe?

Depends what units you want. There are many different conversions possible not just Lon/Lat. UTM is the preferred option when using a topographic map to plot grid references, not long/lat.

Is there any other information with these coordinates?

What kind of other information?

To directly input or to convert these, is a zone number listed with these coords

When given UTM you are also given the zone. That's what the 56H is here in Sydney and further afield.. It is written on the topographic map.

Next how about a datum

You have to use the datum that is on the map. A lot of topos are still in AGD66 not WGS84. Look on a topographic map under the scale. All the required info is there. It's also on the left hand side of the map, with instructions on how to convert to newer datums. And how much error is involved based on satellite derived values based in WGS84. you also need to adjust the magnetic north values based on the info on the map as this moves easterly by 0.1 degree every 3 years. So you need to look at the date the map was published and for when the magnetic /grid angle was correct . So if you are navigating out bush with a map and compass, you really do need to know how the topo works. Remember a GPS is only as accurate as the number of satellites, and it's useless if the batteries die. Navigating by map and compass is well worth learning.

Actually noticed a commonwealth organisation last week still listing and requiring positions in AGD66, yet many assume AGD/AMG no longer is used.

Yes because most maps are 20 years old and haven't been updated by the central mapping authority.

[Big Matt and Shell]

I love this post on some many levels. The first is that you chose an area that I am very familiar with being the spot that I Shell and I lived for a number of years and also where we first joined the NSW RFS. The second is navigation, a bit of a favourite hobby of mine.

It's good to see that NSW have finally moved into the 21st century and have started putting these signs out on major assets and fire trails. We saw them all over the place in SA and heard that this was a key learning from some of the major fires that they had. They looked like this,

This six figure grid is a 100m x 100m square that comes from the UTM reference that you have commented on. To understand UTM a bit better have a read of this article. Basically the globe is flattened and divided into 60 segments (this is your 56 that you referred to) These segments are then divided into 20 latitude bands and assigned a letter reference (this is the H in your post) Each square is broken down further into smaller squares which gives you a grid!

[Richary]

There were also a number of these grid signs on farm gates etc in South Australia. That said I am not sure what coordinate format they were using as they didn't seem to match the UTM I came up with Oziexplorer on the maps.

[Big Matt and Shell]

There were also a number of these grid signs on farm gates etc in South Australia. That said I am not sure what coordinate format they were using as they didn't seem to match the UTM I came up with Oziexplorer on the maps.

A six figure grid reference is just part of UTM reference. They are normally used because the person you are giving it to has a fair idea of the area you are in so they only need the data to narrow down to 100m square where you are. For example to use the originally supplied coords,

56H 0321950 6268624 (the leading zero must have been missing)

If you drop the first 2 and last 2 digits from each set of numbers like,

0321950 6268624 your left with 219 686, this is your six figure reference that you see on these signs.

Here's a slide from one of my RFS training courses, this may make it easier to understand.

[CraigRat]

Thanks for that Matt, very interesting!

I've often wondered about the 6 figure grid, never dawned on me that was how it was done!

[Kerry]

Converted to what? Lat/Long maybe?

Depends what units you want. There are many different conversions possible not just Lon/Lat. UTM is the preferred option when using a topographic map to plot grid references, not long/lat.

Is there any other information with these coordinates?

What kind of other information?

To directly input or to convert these, is a zone number listed with these coords

When given UTM you are also given the zone. That's what the 56H is here in Sydney and further afield.. It is written on the topographic map.

Next how about a datum

You have to use the datum that is on the map. A lot of topos are still in AGD66 not WGS84. Look on a topographic map under the scale. All the required info is there. It's also on the left hand side of the map, with instructions on how to convert to newer datums. And how much error is involved based on satellite derived values based in WGS84. you also need to adjust the magnetic north values based on the info on the map as this moves easterly by 0.1 degree every 3 years. So you need to look at the date the map was published and for when the magnetic /grid angle was correct . So if you are navigating out bush with a map and compass, you really do need to know how the topo works. Remember a GPS is only as accurate as the number of satellites, and it's useless if the batteries die. Navigating by map and compass is well worth learning.

Actually noticed a commonwealth organisation last week still listing and requiring positions in AGD66, yet many assume AGD/AMG no longer is used.

Yes because most maps are 20 years old and haven't been updated by the central mapping authority.

You have this assumption that everybody is using a paper map? This is really a long way distant from the context of this post.

When given UTM you are also given the zone. When given UTM you are also given the zone. That's what the 56H is here in Sydney and further afield.. It is written on the topographic map.

That wasn't the question! The query was does this info exist on the sign so the person requring the info for what ever purpose input to GPS or conversion etc have all the info?

You have to use the datum that is on the map.

Again the query relates to the actual info on the sign, does all the necessary info exist on the sign in conjunction with the coordinates? One should not necessarily have to consult a paper map to determine the proper delination of sign posted coordinates.

[Kerry]

Remember a GPS is only as accurate as the number of satellites

Now that is a complete myth as accuracy is primarily not a function of number of satellites

and it's useless if the batteries die.

Now that part is true.

Yes because most maps are 20 years old and haven't been updated by the central mapping authority.

Totally and utterly not map related, this Gov organisation is just a long way behind the times.

[Big Matt and Shell]

blah, blah, blah (sorry edited to shorten the post)

You have this assumption that everybody is using a paper map? This is really a long way distant from the context of this post.

That is because that is the basis of mapping. So many of us cachers still use the old paper maps especially when we head off into the bush. In fact I would say that it would be irresponsible not to. The thing most people need to remember (and most GPS have this in their start up screen) that they are only a tool to assist in navigation and should be used with a map

When given UTM you are also given the zone. When given UTM you are also given the zone. That's what the 56H is here in Sydney and further afield.. It is written on the topographic map.

That wasn't the question! The query was does this info exist on the sign so the person requring the info for what ever purpose input to GPS or conversion etc have all the info?

This information would normally be given to the emergency services (like the SES) who would pull out a map and look at where you are.

You have to use the datum that is on the map.

Again the query relates to the actual info on the sign, does all the necessary info exist on the sign in conjunction with the coordinates? One should not necessarily have to consult a paper map to determine the proper delination of sign posted coordinates.

I think you missed the point. A reference is no good without a DATUM this is normally shown on the map that the reference is taken from. From memory the difference between AGD66 and WGS84 is about 180m this could mean the difference between being at the top of a cliff or the bottom... It also helps to ensure your GPS is set to the same datum as the current map in the area you are in otherwise the person who gets your reference wont be looking at the same spot.

Lets just try and keep this post fairly simple, otherwise we'll end up down a very different tangent.