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C>As I said above, a physical map is fixed.  But with software, all
 >confusion is possible :).  I can zoom and pan.  Is the center of my map
 >the visible center of my display?  Or, do I tie it to the center of
 >the original map?  It's a rather minor distinction, but I'm curious as
 >to how the professional map people's perspective.
 
My opinion is that projections are an unapologetic compromise to deal
with the facts of life that paper maps are 2D, and paper is limited.
IMHO, digital data should be stored in a universal, unprojected
coordinate system (i.e. lat and lon for this planet), and projected on
demand. Sometimes I want to see an equal-area projection; somtimes I
want to see the rhumb lines connecting places; and sometimes I want to
see the world in perspective as it appears from the moon. If I have a
computer with at least as much processing power as the chip in my
automobile (which is more than they had on board Apollo 11, which in
1969 put the first human on the Moon), I see no reason why I can't have
my digital maps served up my way.
 
On the other hand, a digital map seldom contains all the art and beauty
of say, a Middle Ages portolano, and sometimes I sense that something of
the art and *elan vitale* of mapmaking is getting lost in our brave
new world.
 
A related issue is that digital vector maps can lull the clueless
into a false sense of accuracy (because s/he can zoom in to ridiculus
scales and it still looks crisp). Sometimes it might be better to just
scan maps at a fixed scale, projection and dpi, and as the user zooms
and the map gets "fuzzy", s/he stays aware of the fact that the
resolution of the map is degrading as s/he goes beyond its intended
design.
 
The surveyor crowd I hang with on-line are always dissing me about GIS
meaning "Get It Surveyed" and can cite example after example of people
who take digital 1:2,000,000 scale data and apply it to their back yard
to see if they are in a flood plain or an otherwise legally proscribed
area so they can flame/sue somebody (usually the surveyor, as surveyors
are quick to point out).
 
My response to your comments is that you are asking the wrong question
when you ask about digital map capabilities in terms of paper maps.
Digital maps can be so much more than their paper-based siblings, but
they require software behind them to really reach their full potential.
Comparing paper maps to digtial maps is like comparing bicycles to fish.
 
_   /|   Bill Thoen <[log in to unmask]>
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