on 11/9/2006 2:02 PM Stephen Brown Jr said the following:
At a bare minimum, I would like to have street level maps for a couple of
states and then expand to include the entire U.S.
What would be the best option based on what I want? Also, is there a good
tutorial or reference that explains all these different types of maps
available?
Shapefiles will probably give you the best bang for the buck and with a
little effort on your part and maybe some help from the list, you can get a
very nice looking and nice acting Xastir setup.
Shapefiles are a pure vector format, containing basically just a bunch of
lines from here to there. A "shapefile" is actual a set of 3 files, often
called the "holy trinity" by at least one GIS-type I've come across:
a) map.shp
Contains the actual point data for the lines or points
b) map.shx
I'm not certain, but I think this is an index of the .shp file to make
searching quicker.
c) map.dbf
A very important file; this is a simple flat database with a one-to-one
matching with the line segments in the map.shp file. This is where metadata
about the line segments is stored.
Xastir has a feature called dbfawk that allows you to define drawing styles
(color, line width, and more) based on attributes in the .dbf file.
Tom Russo has a good tutorial on using dbfawk files in Xastir:
http://www.swcp.com/~russo/shape_web/tutorial.html
(I don't know if that's on the wiki -- but if not, it ought to be!)
With Xastir's map properties panel, you can set the minimum and maximum zoom
levels at which a particular map will be drawn. (Using dbfawk files, you can
even do this on a line-segment basis rather than a whole-file basis). This
allows you to use less-complex, and therefore faster-drawing, shapefiles
when zoomed out to a state or nation level, but switch to very detailed
shapefiles when zoomed into a smaller area (county, etc.)
With dbfawk files and the shapefiles generated from the Tiger data
(ftp://aprs.tamu.edu/pub/Xastir/Maps/TIGER/xastir.tamu.edu/index.html), you
could have xastir's maps look exactly like the Tiger server maps - only MUCH
quicker!
Using shapefiles, I was able to use the above maps for the whole state of
Texas. This was good, but my county provides better quality map data (in
shapefile format) that is more accurate, higher resolution, and more
updated. So for my county, I use the county-provided map data and turned off
that county with the Tiger shapefiles.
See result at: http://aprs.lightningflash.net/
I hope this gets you started by answering a few questions. All of use on the
list will be more than happy to answer any more questions you have about
maps -- we all seem to get pretty excited over Xastir's mapping capabilities!
73
-Lance KJ5O
--
J. Lance Cotton, KJ5O
[EMAIL PROTECTED]
http://kj5o.lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the
cookies.
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