Forgive my ignorance on this one, but is it possible (ie does anyone make such a thing yet) to have an in-car GPS system with a monitor that actually displays proper Ordnance Survey maps?
Not long ago I was being shown a GPS system that had been fitted to a Discovery similar to my own. It had a monitor fixed next to the dashboard which in itself was quite neat. However, the actual maps, although accurate in terms of telling you where you are, were extremely disappointing in terms of data - just plain colours and little other information. The zoom level only went into something like 1 kilometer or somewhat.
Earlier today I was making use of
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and it dawnedupon me (not for the first time either) how nice it would be if said in carGPS monitor would display the same information down to streetname level,using the various forms of OS maps such as Pathfinder / Explorer etc? Any ideas anyone?
Just as a quick reference point, streetmap has the entire OS reference set which the last time I looked ran to 26CDs just for the 1:25,000 scale maps. Given that you would also need the 1:50,000, 1:100,000 and probably 1:5000 scale maps as well that gives a rough storage requirement of:
Total of around 164CDs at 650MB each - this gives a total of 78GB which would equate to around 16DVDs.
The reason these numbers are quite so different (you'd expect 1:50000 to be half as many CDs as 1:25000) is that a doubling in the resolution is a doubling in the X and Y axes which gives a quadrupling in the overall data volume. The OS CDs store the maps as uncompressed 24bit fullcolour TIFF files.
While this isn't an inconceivabla amount of data and is easily within the limits of hard disks, no hard disk rated for the kind of shock a car transmits to it is large enough for that data.
16DVDs is obviously impractical for an in-dash navigation system.
The above is without taking into account the road centerline data which the nav systems need to calculate routes which is another few hundred megabytes. If you add in elevation data (as you would want to do for serious offroading with such a nav system) then you double that data volume too.
I used to to this sort of thing for a living in a previous life working for a bit of BT which did Location Based Services - the technology is simple, it's the storage requirements that are large - especially as any good image compression algorithm is lossy and maps can't really tolerate loss of detail. Lossless compression on 24bit images with a lot of random data often increases the overall file size - sometimes by up to 75%.
The only real way to offer the level of detail you want at present is to have the terminal in the car be a display only and have a realtime data feed back to a central server, but that will cost in terms of bandwidth.
Memory-map is very good. For £39.95 inc vat you get their software, and maps covering 1/12th of the UK, it all fits on one CD (and you get to choose which 1/12th). The maps are 1:50000, which is OK for greenlaning if you have the 1:25000 paper maps to route plan. In that price and on the same CD you also get 1:500000 and 1:1M scale maps for general navigation around main roads and motorways.
The quality of the maps is great. I use mine on an old laptop that sits on the Land Rovers cubby box. If I decide to go green laning outside of the areas I currently have 1:50000 maps for then I'll buy them, they do sell
1:25000 maps but only for touristy areas. If you want the whole county in maximun detail then it will cost a couple of hundred quid, but who does? David
Go look at alt.sat.navigation or what ever it is! also look at memory-map.co.uk and google for Fugawi which is a cheaper alternative. For spoken direction look for Tom-tom. There are loads of Applications that do this sort of thing and lots of ways of doing it.
I use a home made sat nav system, very successfully and the whole of the UK
1:50000 mapping takes up about 1.2GB, although it installs from 4 CD's. For street level navigation I also have Microsoft Autoroute installed. All of this runns on a Laptop with Wireless connection to my home network so I can upload/download MP3 music and other data to the car from my house. I have an LCD screen sperate of the laptop installed on the dash bought from Ebay for about £60 quid. If you are going to do it, don't buy until you know what your'e going to use it for and try out as many of the various bits of software first. Start with something like Ozi-Explorer and put some scanned maps into it, for your neighbourhood and go out for a drive!
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