(© copyright 1996-1999, Timothy G. Feeman and Elaine F.
Bosowski.)
boundaries found on base maps and/or in your atlas to
the graticules you generate on the computer. In use for centuries,the like squares method
serves as a means of changing scale, orientation, and/or projection format by transferring
the information that is in one area on a source map to the corresponding area on the map
you are creating.
Before you begin your map compilation, study the base graticules for the source
map (usually a globe or a suitable atlas map) as well as for the map you are creating. Make
sure that you can answer these questions for both graticules:
- How many degrees of latitude separate each parallel that is drawn?
- How many degrees of longitude separate each meridian that is drawn?
- Where is the center of each projection? If on a pole, is it the North or South pole? If
on the equator, is a longitude specified?
- Which way is north? south? east? west? (Warning: North is not always at
"the top". East is not always to the right. This is important!)
Once you have answered these questions, you may proceed.
- For each "square" on the graticule (bounded by two lines of latitude
and two lines of longitude), locate the same "square" on the globe
(bounded by the same lines of latitude and longitude).
- Then, as accurately as you can, copy the land boundaries you find in that
"square" of the globe onto the corresponding "square" on your map.
- You should work on a square by square basis, taking care to work with regions that are bounded
by the same lines of latitude and longitude on your reference globe (or atlas) and on
your graticule.
- Using different regions on the globe and on the graticule is one of the main mistakes
that can occur in compiling a map.
- Getting directions (north, south, east, west) confused is one of the main
mistakes that can occur in compiling a map.
What you are doing is creating proportional squares throughout both the source and
final map. Ideally, one would make accurate maps using the specific latitude and longitude
and mathematically calculating the locations of the point on a new map. For our purposes
in this course, we want you to use highly generalized and simplified boundary lines. Only
the boundaries between land and water will be put on your newly generated graticules.
To highlight the land masses relative to the bodies of water on your maps, you will
draw in only those portions of the graticule that lie within ocean regions. This
will allow the land masses to emerge as the "figure" within the graticule
covered "ground", or oceans.
At the end of the course, you will have a set of graticules and maps that allow you to
see and compare the similarities and differences among and between different map
projections.
Finally, a sketch of the Like Squares method:
