How to define EXTENT

[Banister Trevor]

As long as you are consistent you can use whichever system (decimal degrees,
meters, feet) you want. The map server doesn't really have support for DD
yet, I'm having to fake it out and tell it that I'm using kilometers, which
messes up the scale bar and zoom factor numbers. Use meters, kilometers, or
feet if you can. Whatever you choose, your extents must be in the same units
as your shape file.

You should be able to get some insight by looking at the "world file" that
came with your sectional. If you don't have one, you'll have to create one
so the map server knows where is the world to put it.

A world file should look something like this: (copied from one of Steve's
earlier mails)
This represents the whole world in Geographic format.

0.16666667535901
0.0
0.0
-0.16666667535901
-179.91666666232049
89.91667605005205

Hope this helps.

Trevor

-----Original Message-----
From: Mark Cady [mailto:mcady at clh.net]
Sent: Friday, September 17, 1999 9:36 AM
To: Mapserver Users
Subject: How to define EXTENT


Hi All:

   I'v gotten the demo to work on my Red Hat 5.2 system. (thanks Steve).
I am
trying to get up to speed on GIS since I'm a newbe on that.  I have a
question on EXTENTS.
I assumed that the coordinates were a datum like WGS84. I have looked at
the EXTENT in
demo.map and at my trusty aviation sectional and I don't understand how
to relate the two.
What am I missing? How do I relate lat. lon. to EXTENT. Also in my shape
files do I put in lat. lon.
or EXTENT coordinates.

  I know these are basic questions but I have searched around and have
come up empty
on answers.


TIA

Mark C.