GPS and the Planner

[RJ]

Our regular Thursday evening night event was held on a rough open fellside, Blakeley Raise, which has lots of boulders and small reed patches. Brilliant night venue... loads of point features!

The planner, also the mapper, had updated the map with GPS, producing a highly accurate representation. But.... the area is prone to low cloud and very misty conditions. So he put the controls out without a map.... just a list of features, codes and GPS positions!

Anyone else developing this technique? Seems like a very useful use of technology for controlling. However, I would stress that all the other constraints of planning and control placing apply as well... it isn't an opportunity to hide the controls!!!

[Gross]

There's a tendency out here for maps to be produced using GPS rather than traditional methods. If the GPS is accurate (no idea) and George W doesn't switch off access to US Military satelittes then in the future GPS is bound to play an important role.... but two points in using it for orienteering...

1. It's going to be an added expense & learning experience... maybe the next generation of controllers?

2. Orienteering maps are not neccessarily 100% accurate in location... given the scale & size of map symbols & that an O map isn't there to accurately reflect whats on the ground but to represent the ground accurately... if you see what I mean?

[stodge]

Used Fatboys GPS to get some fixes for some photomontages I was doing in Manchester for a planning application. It got to -+ 8 metres, which although good showed when I tried to line up the closer shots (ie not accurate enough).

I know the planner of the saunders takes GPS fixes once he has found the control site so that putting out in bad weather can be done without mistakes, or by other people.

However I have had the comment from a trailquest organiser when a control was in the wrong place
" it must be right it was put out with GPS "

[FatBoy]

I would say that GPS is a useful weapon in a mapper's amoury but it doesn't replace conventional techniques - it's just not accurate enough, particularly in wooded areas.

The most use I find is when you're updating a map and you feel that a feature or set of features is way out - with GPS you can normally work out whether it's the feature you think is out, or the feature you approached from, or a bit of both - thus helping you decide which bits to remap conventionally. All this of course requires you to be able to fix a grid ref or long/lat to the o-map - hence I do all updates by first getting the map to grid north.

[Kitch]

Gross's point is a good one.
The map needs to convey what is discernable on the ground to the orienteer.
or put another way the orienteer has to be able to recognise the features represented on the map. An absolutely true mapping may not always do this - the mapper interprates.

So.
the planner and controller should find the sights using the map First and Foremost. Just as they should check routes and approaches - its about ensuring fairness.
Having done so then a tape and GPS fix are useful tools to re-locate the sight when the flag needs to be hung.

[grubby]

Use of GPS - What the official(s) need is a 'Differential' GPS unit that, by means of a radio 'correction' signal, is not reliant on Mr. Bush continuing to disable Selective Availability (deliberate error). This feature, which gave GPS units their traditional iregular inaccuracy, was turned off in May 2001 by the Americans. It could of course, be enabled at any time. If you have a conventional GPS unit that is 'DGPS ready' and several are, then by buying an appropriate radio receiver and subscribing to a network, you can be damned sure of exactly where you last relieved yourself on the hill.

If you're a Gizmo Geek you'll love it. Enjoy.

[graeme]

GPS may have some uses for speeding things up, and for mapping, but...

If the planner and controller can't find the right site using the map without use of GPS, why would they think anyone else would enjoy trying to do so?

Graeme

[guest]

I would say that GPS is a useful weapon in a mapper's amoury but it doesn't replace conventional techniques - it's just not accurate enough, particularly in wooded areas.

The most use I find is when you're updating a map and you feel that a feature or set of features is way out - with GPS you can normally work out whether it's the feature you think is out, or the feature you approached from, or a bit of both - thus helping you decide which bits to remap conventionally. All this of course requires you to be able to fix a grid ref or long/lat to the o-map - hence I do all updates by first getting the map to grid north.

The technology is out there; I remember using a GPS system in Spain that had an accurancy of 1cm if it had a good lock. It also locked onto height that was accurate to a few cm - the whole thing was based upon sat but also land 'beacons'. Surprising thing was that it still seemed to get a half decent lock in thickish pine forest. Problem is that any type of forest thicker than this then GPS becomes as good as useless. Having said all this, the kit I was using was worth a couple of grand - and in open areas would be good to map contours just by doing transects of the hill/area.

As someone mentioned earlier I suspect a lot of orienteering maps probably do not correlate to grid/gps references e.g. planner may use a bit of license in contour mapping etc. Also, off the shelf GPS systems from Halfrauds etc probably do not (and on the whole do not need) have the requisit level accuracy to determine features on an o map.

[Nails]

The mappers of WOC 2005 in Japan used GPS for creating their basemaps. They have differential shipping beacons all along the coast which allowed very accurate position to be gained. But as gross and kitch have pointed out (and the WOC 2005 mappers) its all about interpretation and not 100% accuracy.

The technology is out there; I remember using a GPS system in Spain that had an accurancy of 1cm if it had a good lock. It also locked onto height that was accurate to a few cm - the whole thing was based upon sat but also land 'beacons'. Surprising thing was that it still seemed to get a half decent lock in thickish pine forest. Problem is that any type of forest thicker than this then GPS becomes as good as useless. Having said all this, the kit I was using was worth a couple of grand - and in open areas would be good to map contours just by doing transects of the hill/area.

I've used similar system myself and must be stressed that walking round a 500m square development site is ok -but you wouldn't want to lug that equipment about a forest!

[graeme]

its all about interpretation and not 100% accuracy.

In some parts. But actually the skeleton of most maps (path network, streams) are
about 100% accuracy: its only the contours you want to be wrong, and the terrain features they drag with them. And those skeletons will be accurate enough to build a first rate O-map later on (unlike maps based on OS). Moreover, there's only a handful of mappers in the UK whose interpretation is clearer than 100% accuracy would be.

With combined OCAD/GPS it will soon be possible for amateur mappers to produce fairly good maps, and it will be interesting to see when they become accepted as standard (in the way laserprinted maps now have).

Graeme

PS Who's mapping the JK?

[FatBoy]

I'll agree with both of you. The line features need to be accurate and it is all about interpretation. I don't think you can say it's as simple as bending a few contours. One needs to decide for example that the path is indistinct and not a small path (very important for night-o!). GPS doesn't tell you this.

Most of the real accurate GPS units I've seen aren't exactly what you want to take up into an exposed area mid winter - a bit large. One thing you also have to take into account with GPS is when it says accuracy 2m (for example) it's actually 4m relative as it will be 2m out one way then 2m out the other way. That said 4m is close enough, but 10m (hence 5 displayed) isn't really.

I do find on some areas the altimeter being perhaps even more useful than GPS. You've got some base contours which don't show some land workings and you're deliberating which contour to bend - go to a known line feature/contour crossing and take a height reading - go to the workings and see. Unlike GPS altimeters tend to be reasonably accurate one minute to the next (but not day to day).

[Nails]

Yes graeme i was talking about detail and not the skeleton of a map -of course gps is good for making basemaps! Just pointing out that its not the b all and end all of a good quality o-map. Perhaps it should be seen as a useful tool for intial survey -then using this accurate base for fieldwork.

I also agree with FatBoy -an altimeter is a useful tool for deciding height -for example a small crag in an otherwise featureless slope. If you know your height -easy!

[graeme]

Agreed Neil, thats why I said

"its only the contours you want to be wrong..."

I'm a bit surprised nobody disagreed with that yet!

Graeme


PS Why do 1m crags always lie on the 5m contour lines?

[tokoloshe]

I have used GPS for mapping like Fat Boy - to try to resolve problems. One thing I found with my unit was that it was important to give it time to settle when trying to fix a spot. My first attempts when I stopped, pressed the button to remember a waypoint, and moved on were hopeless. I have found that it takes up to a minute stopped to be confident with the waypoint coordinates. Although it takes longer it is sufficiently accurate in open areas and mixed woodland but not in thick pine, in a reentrant on an overcast day.

And for Graeme - as one of the original mappers for Norman's Law 32 years ago (you should have a good base map) I hope the event goes well.

[graeme]

Drifting way off topic...

I have the BUSA course on the old Norman's Law map. Of the 20 control sites on natural features (rock/contour) only 3 are marked on the new Peel map.

I wouldn't say either was "wrong", but its an amazing demonstration of how mapping styles have changed.

Graeme