Tony Walsh said:The only thing I've
never been able to get used to is the 15m contour interval - I've not
yet worked out why harvey's thought that was a good idea.
If you want to find out then look at the difference between 15 and 10m
contours somewhere steep... With 10m contours there is simply too much
information to get everything in! OS maps frequently remove contours
between references on really steep areas, and this isn't obvious until
you either look very closely at the map or find your descent plan is one
helluva lot steeper than you'd bargained for!
Probably the best example of Too Much Information is the OS 1:25K
Outdoor Leisure map of the Cuiilin, where there's so much brown it's
verging on impossible to follow the actual shape of the ridge. It's
/tricky/ on the standard Harveys, but the deliberately simplified,
exploded view on the back with /less/ information presented is actually
much, much clearer because it's much cleaner.
In a similar vein, Norwegian topo maps, that typically deal with more
relief than you have in the UK, have 20m contour intervals. Don't
forget that 10m has been selected to usefully portray the whole UK, and
map it at a standard, so you have something that needs to work
acceptably in Norfolk as well as Lochaber. For seriously steep stuff
though, and Harveys tend to concentrate on that sort of ground, bigger
contour intervals can actually make a lot of sense.
Having said that, it should be noted that many Harveys maps were
originally published at 1:40K, and the amount of information presented
had to fit in a smaller space. The reason for the expansion to 1:25K
seems to be marketing rearing its ugly head, with a common perception
that Bigger Is Better. Comparing the current 1:25K to the original
1:40K maps many were sourced from all you have is more paper, which
means more unwieldy in use and no extra detail, which I find /very/
annoying. The 1:40K from Harveys were originally made for KIMM mountain
marathon events, with mountain navigation by individuals a specific and
major point of their design, and for the most part they're as good as
anything I've seen. The 1:25K blowups of the same are poorer because
you could more info in the greater space and not lose clarity.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/