Newsgroups: comp.infosystems.gis
Date:         Thu, 16 Apr 1992 11:33:35 PDT
              <GIS-L@UBVM.BITNET>
From:         Rich Taketa <TAKETA@SJSUVM1.BITNET>
Subject:      Re: perspective on Geographic
              16 Apr 1992 08:22:52 -0400 from <kclarke@RESDGW6.ER.USGS.GOV>

Frans Rip writes:

I wonder (as non-geographer/cartographer) why SCALE would be the
criterium of interest.
Wouldn't 'area size', or 'spatial resolution / object size' be
more appropriate ?

        Scale implies a level of generalization, or "abstraction" for
        information as presented on a map.  This carries with it a notion of
        spatial resolution.  Although a GIS can heoretically store
        information at any "scale", in actual practice the information is
        recorded at a specified scale and displayed at a specified scale.

After all, using GI-systems implies a separation between the digital
model of the earth (or part of it) and the visualization of aspects of
that model (a map is just one of the ways to do that).
Therefore, definition based on map scale seems to miss the heart of
the matter.

Shouldn't you map what is of interest, on a scale that shows what you
need to see ?
The distinction between a map and a plan is arbitrary indeed !

        True, as in the engineering "maps" used by public utilities.  At what
        point does the engineering site plan (which could cover many square
        kilometers) become a map?  And does it really matter?  However,
        one should always be cognizant of the scales being used to collect
        and display the data, and the relationships among the scales of
        collection, storage, and display.

And one step further: why only think in maps ? Maps are just one group
of projections (i.e. vertical) of the data on your presentation
platform. Move your (virtual) camera, look at it from a different
angle ! Shift your focus ! Visualize earth rather than only mapping it !

Peter Halls writes:

This debate, surely, is in danger of resurrecting the debate of Geographic vs
Spatial.

Like it, or not, we are now effectively 'stuck' with the term GIS for the name
of the mechanism for (computer aided) storage, manipulation, management,
analysis and reporting upon spatial (or geographic (note the small s this time))
information.  If the 'geo' is to be regarded as pedantic, we have to invent
a new term for the analysis of the spatial relationships of features on other
planets.  As a Geologist, I am unaware of replacing the 'geo' when we were
examining samples of moon rocks some years back!

Likewise scale!  If you are working on a planetary scale, then (for the earth)
a scale of 1:50000 would be a highly detailed plan!  If you are examining
plant communities, or soil stability, 1:20, such as an architect's site plan
might well be the point at which you change nomenclature from 'map' to 'plan'.

For me, the power of GIS is that it is, essentially, application INDEPENDENT;
unlike scale, the pedantic meaning of 'geo' and such like.  At York I have
research workers of many disciplines using (to a greater or lesser extent -
many of them have yet to understand the sheer power potential of the tool they
are using) GIS to examine spatial data that covers areas from the whole world
(and whole 'other' planets) to floral variations within a SSSI (Site of
Special Scientific Interest).  Our recent General Election looks likely to add
yet another group of workers as they try to analyse the results and to try to
understand the background to those results.

Lets put some more effort into promoting the opportunities of GIS, and the basic
needs for affordable base map information in a digital form and at an
ecconomic (for the user) licence fee, rather than this childish bickering as
to whether what 'so and so' is doing is GIS!

        If this discussion remains highly theoretical, then I would agree.
        However, in the practical world of software, developers make
        decisions that affect the usability of their product for various
        applications.  Some of the most fundamental are the choice of digital
        precision for coordinates (which affects the range and accuracy of
        coordinate values) and the way in which floating-point numbers are
        compared (commonly using tolerance values).

        The decisions are a fact of life in software development, and I do not
        imply that software developers are in some way taking shortcuts.
        However, I do think that specific instances of computer hardware
        and software end up being more capable of addressing particular
        ranges of problems.  In the case of GIS, software may be designed,
        developed and tested to address a particular range of scales.  I know
        from experience that although almost anything can be represented in
        computer, not everything is represented equally well.


Keith Clarke writes:

I think Frans has helped me somewhat in something I have been thinking
about for a while, i.e. what is the difference (and similarity) between
cartography and GIS. Concern for the map, i.e. its projection, scale,
level of generalization, is obviously cartography. Visualizing information
structure in data is obviously GIS. Once again, I think that the overlap
is more important than the differences. Cartographers make maps, but should
be concerned about geographic information. GISers (what is the real term..
perhaps geographic information analysts) analyze geo-information, but I
think they also should be concerned about cartography. The cartography/geography
link is about a hundred years old, there's no need to break it because of
one new technology.
P.S. Is an oblique air photo really "visualizing the earth rather than mapping
 it"?

        I would think that "reading" the aerial photograph (oblique or
        otherwise) would be the visualization part.  One could argue that the
        "mapping" of earth features onto the photo is a matter of physics and
        chemistry.




Rich Taketa
Department of Geography and Environmental Studies
San Jose State University
San Jose, California   95192
(408) 924-5425
taketa@sjsuvm1.BITNET
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