Global Positioning System Reference
In-Depth Information
CHAPTER FOUR
Mapmaking
After a brief historical excursion, we look at the problem of map projections:
how to represent the three-dimensional surface of our planet on a piece of
paper. We will see that there is no way to do so with perfect accuracy and that,
as a consequence, many different map projections have been promulgated
over the centuries, to enhance this or that feature of the earth.
The First Two Thousand Years
The long and winding story of humankind's struggles to develop accurate
maps is in many ways a sorry tale, at least in the West. After a bright start, it
gets stuck. Misconceptions were accepted and then became enshrined for
millennia. My account of early mapmaking is, metaphorically, shown in
large scale—covering a great area but with little detail. There is a danger in
this approach: if I pick out a few key events and skip over many others, you
may join the dots in a linear fashion. You might then quite naturally
consider that mapmaking progressed in an inexorable steady stream, like a
rolled carpet unfolding. It didn't happen like that. For every influential
figure I mention, there were a hundred others. Many of them doubtless
made more telling contributions or were less wayward in their understand-
ing of mapmaking. Space precludes a full discussion (an irony, I suppose). I
cover a few key subjects of which we have a reasonable knowledge and
omit others of which we don't or which are controversial. As always, I will
point those readers who yearn for more detail toward references that
provide such.
In the West, cartography starts plainly enough with the Greek philoso-
phers. Later, it becomes entangled with aspects of navigation, exploration,
the geographical expansion of nations, and mercantile interests. It be-
