There are, of course a vast number of issues here!
The main issues are fairly straighforward, though. I wrote a response
to an article on "Citizen Based mapping" by Roger Longhorn in
Geo:Connexion magazine, as follows:
I have just read Roger Longorn's article on citizen based mapping, and
in general have to applaud much of what he says. But I think he
oversimplifies the problems that CBM faces to be generally acceptable,
in only considering the completeness aspect of the resulting database.
There are other issues around quality, compatibility and trust.
Quality is an important issue for geographic data, and has to be taken
very seriously by any supplier of digital geographic information. Either
a supplier of such information guarantees a certain quality standard, or
information is provided about source material etc. The former approach
is that used by organizations such as the Ordnance Survey, the latter in
products such as the Antarctic Digital Database (www.add.scar.org,
managed by myself), which is a compilation of information from many
sources. Any citizen based mapping must address the matter of quality,
so that the fitness of the data for a particular purpose can be
assessed.
Compatibility is another important matter. For example, say I am
mapping a road. Do I regard the margin of the road as the kerb, or does
the road include the pavement (sidewalk for our North American friends)?
Any citizen based mapping must provide a set of feature definitions that
the user must adhere to before data can be added to the database. There
are standards for creating suitable vocabularies (e.g. ISO 19110) that
would have to be part of the fundamental underpinning of any such
project. Remember, too, that we live in a plural society, and we cannot
rely on English being the first tongue of a citizen, nor can we rely on
all English speakers using the same version of English, as I pointed out
above with my reference to pavement/sidewalk - to a North American
English speaker, the pavement is the entire metalled surface of a road!
Trust is perhaps the hardest issue for citizen based mapping. If I buy
an Ordnance Survey map, I am buying a product which has proved to be
trustworthy over a long period. If I suffer damage because the Ordnance
Survey have been negligent in mapping an area, then I might well have a
good case for obtaining redress from them. In the case of the Antarctic
Digital Database, where we cannot be so certain of the accuracy of the
mapping, we have to make careful disclaimers to ensure that users have
no doubt as to the nature of the product they are using. In both cases,
we trust the product to consistently reflect the quality statements made
for it. But in the case of citizen based mapping, how do we know that
the data contributor has provided accurate information? How do we know
that the contributor has not (for whatever reason) distorted the
information contributed to the project? And this may be quite innocent -
the contributor may only map features of personal interest, and leave
out other features of more interest to the general public. Or the
contributor may simply not be aware of a rather obscure pathway - I am
sure there are pathways in the village where I have lived for 25 years
that I am not aware of! As I said, I think this is the hardest part, and
I think that there must be a mechanism for generating "trust ratings"
for contributors so that a contributor whose data is consistently found
to be accurate and complete gets a higher rating than one whose data is
found to be less satisfactory.
Finally, and I am sure that Mr Longhorn is aware of this, there would
always be a temptation for a contributor to plagiarize copyright data.
How is this to be guarded against and policed? After all, accurate
information from whatever source is going to look much the same! So, how
is a CBM project going to be able to provide a defense against the
accusation that contributed information was copied from another source?
As we all know, some mapping agencies have a very proactive attitude to
copyright protection!
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