AZ_PROJ.FAQ released with AZ_PROJ v1.04

1. Is it possible to fill states/countries/islands with
colors?

	The short answer is no.

	The .wdb files contain geographic information in the form of
a series of points (given in lat/lon) which are joined by az_proj
to make a map-line (also called wdb path). The wdb file consists
of series of these map lines each of 30-500 points. Postscript
can fill areas bound by such lines if they form a closed path.
However the map-lines in the .wdb files generally do not join
one to another, are not traced in the same direction and records
in proximity in the file do not necessarily describe closely
related pieces of geography. Thus in general it is not possible
to join these lines to make a closed loop which can then be
filled using the Postscript "fill" command to make (say) all
of USA green and all of Australia red. The wdb pathes making
the large lakes have all been edited by hand, so that the lakes
can be filled (with blue).

	The long answer is no also.

	Even is someone edited all the paths to be closed loops,
the maximum number of points in a postscript path is somewhat
less than 1500 (depending on what else is sitting in memory).
Except for simple paths like state borders, most continents etc
are made up of more that 1500 points.



2)	Why do the bright colors on the display (like light
blue for lakes) become darker on a color printer (like
murky grey blue)?

	This is because of the different conventions used for
RGB on a display and a printer. Printers are linear devices. You
give it G=0.25 and the print reflects 75% of the green (and 100%
of everything else). A display doesn't absorb or reflect anything.
Instead light comes from the screen, an amount which is non-linear
in photons/grid voltage (or some control function). Since all
phoshors are about the same as each other, there were no great
compatibility problems between different TV screens and no-one
really cared about the non-linearity. However you can't run a
printer or display off the control signals designed for the other
type of device, without doing the conversion (called a "gamma"
correction). Postscript does not ask the device it is running
on whether it is a printer or a display, so other subtle ruses
have been devised in az_proj to handle the situation. We've
assumed that the output is to a display. Postscript can ask
the "product" it's running on, and the product will return
a string (eg nothing, Deskjet550C). If the string matches a
known printer (we know Deskjet550C, 1200C or Apple Phase IISDX),
then we do the gamma correction.

	If your printer is another color printer, then follow
the instructions in az_proj.ps for detecting your printer
(you'll have to duplicate a few lines and put in your string).
Look for the string "gamma" in the code to locate the place to
start changing things.

3).	Can I spread my map over several piece of paper, and
later tape/staple/glue them together to make a bigger map?

	Yes. For further details, see the center_offset
feature in az_ini.ps

4)
Where's the .exe file?

	Some of you ask me.

	The answer is that there's _NO_ .exe file in the AZ_PROJ package.
The package consists of a set of files which when printed on a Postscript
printer will produce a map of your choice. The files are all Postscript,
which is ascii and can be edited by a normal programming editor i.e.
an ascii editor. Do not use a word processor to edit the files, unless
it can be run in ascii mode. If you want to use these files to
create maps on your monitor, or to print to a non-Postscript
printer, then you need to find a Postscript Interpreter that
will make allow you to do this. This interpreter will be
different for different operating systems. Ghostscript (see
elsewhere in this file) does a good job of this for
DOS, Win, DVX, OS/2, Unix and this is what we used. There are
other programs that do the same job, that I have not tested
with AZ_PROJ.

	So the answer is that you have to supply the .exe file (the
Postscript interpreter) or else a Postscript printer. (For information
on getting Ghostscript, see the README.AZP file).

	Joe NA3T
	Nov 1996
