Most map file formats like WDB, MIF, etc. basically are designed for pen
plotters.  That is, connecting the dots when the pen is down, lift the pen
up, move it somewhere else, put the pen down and connect some more dots.
In ASCII they look like this:

n
lat1,lon1
lat2,lon2
.
.
.
latn,lonn
m
lat1,lon1
lat2,lon2
.
.
.
latm,lonm
.
.
.

where you connect n points, lift the pen and then connect m points.  In DX,
the connection type would be lines.  The coordinate would be positions.
The connections list corresponds to the order in the list, but you don't
have a pair of coordinates for when the pen is "lifted".  In the sample
data I sent you from WDB II for the US, that's what I did from the original
WDB II data or in the WDB I data used in the WorldMap macro.  Of course,
the original data were in EBCDIC and derived from hand digitizing maps,
which is the inverse of this process.

FYI, formats like MIF will add attributes to the lines for various
properties.  Similar things are done by many GIS packages.  I hope this
helps.




"Allard" <[EMAIL PROTECTED]>@opendx.watson.ibm.com on 02/11/2001
03:16:44 PM

Please respond to [email protected]

Sent by:  [EMAIL PROTECTED]


To:   <[email protected]>
cc:
Subject:  [opendx-users] World Data Bank file question




I would like to thank Lloyd Treinish for his help with getting  the world
map mapped onto some GIS data that I'm using, but I also have a  question.
Is there an ascii example of how the World Data Bank data is  formatted?
I'm trying to use mapping data sets from SAS to put state  boundaries and
other geographic boundary features onto my data, and I noticed in  the
WDBI.dx file that there are segments involved for making the  connections.
SAS seems to do a similar thing.  I have managed to  produce a map with
just the lat/long coordinates showing up as points using the  SAS data set,
but I would also like to put the segments on there so one can  actually see
the drawn state borders.

Once again any help would be appreciated.


Reply via email to