Tag Archives: Topographic

UK Topographic Mapping for a Garmin GPS

One of my very early posts that still gets regular traffic is this post on the problems of getting good topographic data for the UK for a Garmin GPS. Back then whilst you could get hold of a topographic mapping for the United States, in the UK it was very difficult.

Subsequently Garmin released their Garmin TOPO Great Britain product which whilst it was an improvement still isn’t great, and is eye-wateringly expensive – the whole of the UK retails for £150. There are several problems with it, firstly if you come from having used a regular Ordnance Survey map there is a distinct lack of detail, and also in a number of places due to copyright issues paths are missing. Garmin themselves alude to this on their website when they say “includes many tracks and paths”.

Following on from that, and with the more powerful processors and colour screens in more modern GPS units Garmin have now added their GB Discoverer product. This contains the 1:50,000 Ordnance Survey mapping for the whole of the UK, but again it’s expensive – retail is £200 – although it is included in a number of special packs with various GPS units so you can save quite a bit by buying the maps at the same time as upgrading your GPS unit. The 1:25,000 mapping is available for download in 600sq-km chunks at £20 each – so you’re looking at over £8000 for the whole of the UK. The OS mappings are also not without their issues, chief among them is that they are raster based maps rather than vector based. Essentially the maps are high quality scans of the paper maps so zooming is limited as the maps are pretty well useless if you zoom in too far for a particular map, or if you zoom out too much.

The following screenshots taken from my Garmin GPSMap 62S show some of the issues.

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The first two pictures are of the junction of Nine Mile Ride and Lower Wokingham Road between Finchampstead and Crowthorne. You can see the difference in detail between the 1:50,000 and 1:25,000 mapping at the 500m scale, however look what happens when I zoom in to 50m. On the 1:50,000 you can see the jagged edges caused by zooming in too much, the 1:25,000 is better detail wise, but there are still zooming issues apparent.

Now take a look at these two shots, again from my Garmin GPSMap 62S.

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There isn’t quite as much detail in places, certainly not compared to the 1:25,000, but there isn’t the zooming issue. If I also say that this map is absolutely free to install onto your Garmin GPS, it starts to get more interesting.

The map is using data from the Open Street Map project, started in 2004 by Steve Coast as a result of frustation at the vast amount of data Ordnance Survey in the UK kept locked away. You can take a look at the full map at OpenStreetMap.org. Whilst the coverage varies, in general after a decade of work the coverage is now pretty good across the whole of the UK. It takes a bit of work to get it to a usable form for a Garmin GPS, but again that is freely available from the site of talkytoaster, a UK Geocacher.

There are other advantages. I’ve had the Garmin GB Discoverer in my GPS for a number of years now, bought when I upgraded my GPS. Whilst the road maps in my regular Garmin Satnav are upgraded quarterly, the Ordnance Survey mapping has never been updated. Whilst mountains don’t move, new housing estates are built, roads change route and new roads are built, so steadily the sizeable investment people have made in maps goes out of date.

It’s different with the Open Street Map project. The UK mapping from talkytoaster is updated every two weeks, again for free. Another example:

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All of the shots are of junction 11 of the M4. You’ll see that the 1:50,000 and the 1:25,000 aside from the resolution differences show the same layout of the roundabout. As anybody who lives around Reading will tell you over the past few years there have been significant changes in the layout of this junction, changes which aren’t reflected in either of the OS mappings. However the layout from the Open Street Map data is different, as you can see from the third shot, and in the fourth I’ve overlaid the OS 1:25,000 with the Open Street Map data to show the difference.

So in summary your options for a UK Topographic Mapping for a Garmin are to go with the official options – £150 for a not great vector based topographic mapping or £200 or over £8000 for detailed raster based mapping that doesn’t get updated, or a free vector based mapping that is updated every two weeks… If you need the detail then that might sway you towards the OS mapping, but for the older GPS units that don’t support raster based maps it’s not really too hard a decision really…

Back Searching the Countryside with Mapsource GB Topo

Over the past few months I’ve been thinking that I really should get some more exercise. One of the ways I tended to do that, before I worked at SSE was by Geocaching, however over my time there with the extra time I was spending travelling, plus a lot of other demands on my time our caching trips generally reverted to being on holiday only.

A couple years back I wrote about the lack of UK topographic maps from Garmin, and discussed a way around the problem. However since then, Garmin have addressed the problem with the release of Mapsource GB Topo – although subject to a number of limitations as to what the user could do with the Ordnance Survey data it contained. However it didn’t particularly help me, as it was only supported on the newer generation of eTrex units, not my first generation eTrex Vista. Anyway, since we were only really Geocaching on holiday, and Topo Canada worked fine on my old GPS, it didn’t really bother me much.

With the decision to get some more exercise, I took a look at doing some more UK Geocaching, and came across a whole raft of special offers at GPS Warehouse, including a bundle containing the latest generation eTrex Vista Cx, and a copy of GB Topo too. I couldn’t resist and put my order in. It has to be said that there was a worrying moment or two, as in the past packages from them have arrived the next day, and this one took a few days to despatch, but anyway, the new GPS arrived this week. Incidentally, if you look down the list of offers, there is quite a range, including a number of cheaper packages, however I opted for an eTrex Vista again because it includes the electronic compass. Whilst it is possible to go Geocaching with a unit without this, personally I’ve always found it is better to have a unit that correctly reads the direction in which you are facing when you are stood still – the other units, that base the direction on the direction of last movement are a bit more of a pain, especially close to the cache. However if you want a cheap and rugged GPS to get started, you can’t go wrong with the classic yellow eTrex – which you can currently pick up for £69.99 from GPS Warehouse.

Old and New eTrex Vista

Unpacking my new eTrex Vista, it was a slight case of same yet different. You can see what I mean from the picture – the new unit, although laid out in exactly the same way as the old one is somewhat shorter and fatter than the original, I suspect because the colour screen in the new unit is a more conventional shape for other devices that are using colour screens. Hardware wise, the old style serial port has been replaced with USB – a relief as my laptop doesn’t have a serial port, and the serial to USB cable I have doesn’t like Windows Vista-64. The new eTrex Vista uses exactly the same cable as my Streetpilot i2, and so is quite happy thanks to the 64-bit support from Garmin I discussed recently. Alongside this, the new unit now makes a selection of beeps during operation, including a useful proximity alarm when you get close to a Geocache. Software wise things have moved forwards. There is explicit Geocache support – back when I first started there weren’t even Geocache icons in the default set, these didn’t arrive until a later software update for the units. The unit also takes the same sized microSD memory cards that the Streetpilot i2 takes which is useful, and the software has been expanded to include a routing mode. However I wouldn’t recommend it for road navigation as it lacks the voice directions – it only beeps to tell you of a new instruction, meaning you have to look at the screen to see the next direction. In my opinion, the most important thing for a road navigation unit is good clear spoken instructions as the last thing you should be doing is to take your eyes off the road to look at a little screen – hence what you need is a good reliable unit with spoken instructions and a simple interface, hence why to some peoples surprise I opted for the black and white Streetpilot i2, rather than a more fancy unit.

Anyway, back to the new eTrex Vista. For Geocaching, my requirements are somewhat different. I’ve already mentioned the importance of the electronic compass, but with the colour screen and the topographic maps, alongside the fact that the unit is rugged and fully waterproof, coupled with the small size, it is great for a bit of caching. So this afternoon I took it out for a spin, trying a couple of local caches.

Back when I first went out caching, caches in the UK were few and far between, indeed our Queens Oak cache was the first cache to be placed in Berkshire when it was hidden back in 2001. Now when I pulled the list of the closest 100 caches to home from the site, all the caches were between the line of the M4 and M3! Whereas for a long while our closest caches were our own, just two miles away, there are now twelve caches closer to home than those.

As I had a couple of errands to run at the Church, I opted to try the Finchampstead Microcache, and Rectory Hollow caches as these were a short walk from the car park there.

Late Afternoon Finchampstead Fields

The closest was the microcache, a 35mm film canister hidden close to the path down from White Horse Lane to the village, which as implied by the description on the page, didn’t prove to be too much of a problem to find. One of the things you pick up quite quickly when caching is there are a number of common places people will hide things – indeed one of the reasons I drifted away from caching was due to the repetitive nature of a number of the caches. However it was the first time I’d actually explored this bit of Finchampstead, and I was treated to some quite stunning views across the fields in the late afternoon sun.

Next on my list was Rectory Hollow, which was a much larger box, but also had reports of issues with the co-ordinates. The cache owners had checked several times, and usually got the right co-ordinates when approaching from the north-east – the direction from which I was coming. This one was again alongside a path, but this time the path from the Church that heads down towards the Tally Ho pub and Eversley. Oddly enough, although the GB Topo included the footpath from the Church (or at least from the point where it is only a footpath rather than the access for a couple of houses on the top of the hill, the part of the path on from where it meets the Whitehorse Lane to the Village path is missing – a common problem. According to this discussion (relevant statement is about a third of the way down the fourth page) the problem is down to the quality of the data supplied by the Ordnance Survey. Apparently the vector mapping includes only those paths surveyed by the OS surveyors – paper maps and the raster mapping generated from them include right of way information licensed from local authorities that isn’t licensed here – as the vector mapping is primarily aimed at business who have more interest in urban and city areas, the vector mapping is apparently more accurate there.

Heading down to the cache site, and trying not to look suspicious to the various dog walkers I passed, I actually initially missed the cache site as the proximity alarm for the cache didn’t sound. This was because the co-ordinates placed the cache out in the middle of the adjacent field. I tried moving out from under the trees, and trying again, but the GPS was consistently placing the location in the field, necessitating a more detailed search to try and find the box. Unfortunately I’d hit the time of day when quite a few people were out walking their dogs, so that combined with the problems with the co-ordinates meant that I decided to call it a day and head back to do what I needed at the Church. I’d got the bit of exercise, which was the point anyway, even if I didn’t find both caches. I’ll head back another day when hopefully the geometry of the satellites will be such that I can get a better fix on the location.