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A few days ago someone asked for help in acquiring computerised maps
for their study of 19th century liberalism, and earlier today I
received another broadcast asking for pointers towards digitised maps
of London. As there seems to be a widespread interest in such imagery
I have jotted down a quick guide to one web resource, followed by
a short discussion of the copyright problems etc. I hope that it will
be found useful. Please feel free to cross-post it to any other lists
as the software discussed will generate images of anywhere on Earth.
Undoubtedly, the best way to try this will be to print this message
out and then follow the instructions `live'.
1.If you have access to Mosaic or any of the other graphic web
packages, point it to the following:
http://pubweb.parc.xerox.com/map
(This is Rank Xerox's public web map section, via which anyone can
focus on any part of Earth from any height. Only outline images are
shown, though lakes, rivers, national borders and grid lines can be
put on too.)
2.For those interested in British and Irish images the best
thing to do is to pick UK from the list of options presented. Others
may wish to choose USA or whatever.
3.Choose sinusoidal or another option (this allows you to view the
image as it appears to the eye from space or have it flattened out to
take account of the Earth's curvature).
4.Select borders to have international frontiers marked. (Or don't)
5.Find the interface where commands are entered and input:
/nogrid/ht=9.00
This will switch off the map grid squares and zoom in on the image at
a height which makes further refinements easy.
6.Use the cursor to highlight any smaller areas e.g. Northern Ireland.
7.Reset the height if a further adjustment proves necessary. You can
also move left and right a bit.
8.Now the complicated bit. Unfortunately, a slight bug in the system
(well, that's what it looks like) means that in order to download the
image one has to switch off the viewing screen. It may have been
fixed by now as I got a technician to complain about it! If not,
one will have to free up space on the screen for the download menu to
appear. Enter:
/noview
at the command interface.
9.Choose Other Remote Viewer and save it. In my case I had to use a
central server and get a technician to email it over to me from
there. Others won't have that problem.
As I said, the facility can be used to retrieve outline images of any
region on Earth. I found it extremely helpful in showing that
historians pick a starting image which helps to justify their version
of the past. The British Isles map which the BBC uses in its weather
reports is taken from 611 miles up. If this is the natural frame of
conception or reference, the Irish republic seems to have bucked a
trend of history towards unification. The RTE map of all-Ireland is
taken from (if I remember correctly) 450 miles up. If this image is
correct then Northern Ireland's unionists suddenly appear to be the
odd ones out. I've built a thesis up on this premise...
Anyway, the important issue here is that Xerox's images are part of a
public web facility. This, I _assume_, means that it is free of
copyright, though I know that others are much more reluctant to part
with such images free. Friends of the Earth, for instance, have to
negotiate prices with various data suppliers. Unless it is clip-art
supplied free of copyright to the purchaser (which tends to be
rubbish anyway, as in Microsoft's ridiculous picture of Ireland) it
is best to treat such images as a still from a film or a picture from
a book. Just a warning.
The other thing to note is that these files can take up huge amounts
of disk space if saved in the wrong format. The best bet is to try to
get them into a word processor package as a black and white graphic
file, in which case you will probably be able to fit several onto a
floppy disk. When I recently digitised the Daily Telegraph weather
map, on the other hand, the one colour image made was 8mb in size. So
watch what you're doing!
FInally, I heard some time ago that David Miller, the distinguished
Irish historian and avid computer buff, was making a study of Ireland
which involved digitising whole swathes of it. I don't know if this
is true (though his plans for the data seemed facinating) but, if it
is, he may be able to provide a few more pointers.
If anyone else knows of alternative sources of images I'd be
delighted to hear from them.
All the best,
Sean.