[Xastir] Making better looking maps

[Tom Russo]

On Fri, Aug 10, 2007 at 09:00:29AM -0400, we recorded a bogon-computron collision of the <k1lnx at k1lnx.net> flavor, containing:
> 
> I do have one question on the downloaded Tiger data. When I unzipped
> Tennessee for example, it created two directories, Polygons and Polylines.
> In the corresponding directories I see (I'll use my home county as an
> example):
> 
> /usr/local/share/xastir/maps/static_maps/TN/Polygons
> -rw-r--r-- 1 root root 1352805 2007-05-08 15:06 Carter_County.dbf
> -rw-r--r-- 1 root root 1276956 2007-05-08 15:06 Carter_County.shp
> -rw-r--r-- 1 root root   25156 2007-05-08 15:06 Carter_County.shx
> 
> /usr/local/share/xastir/maps/static_maps/TN/Polylines
> -rw-r--r-- 1 root root  2534921 2007-05-08 15:04 Carter_County.dbf
> -rw-r--r-- 1 root root      143 2007-05-08 15:04 Carter_County.prj
> -rw-r--r-- 1 root root  1709364 2007-05-08 15:04 Carter_County.shp
> -rw-r--r-- 1 root root   104580 2007-05-08 15:04 Carter_County.shx
> 
> What is the difference between the Polygons and Polylines directory, if any?


They are completely different, and you need both for good maps with all the
features.

Polyines are linear features like roads, streams, etc.
Polygons are area features like parks, reservations, military bases, lakes, 
reservoirs, etc.

It is a limitation of the shapefile format that a single file can contain only
one type of object (point, line, area), so for data that has lots of different
types one requires lots of different files.

This question has been asked so many times that it's a FAQ that needs to get
answered in README.MAPS.  It isn't.  I'll go put it there now, and on the 
Wikified version.

> What file or files do I edit to start customizing colors, line widths, etc?

This is done in the "dbfawk" file associated with the data.  This is sorta
answered in README.MAPS, but not explicitly.

There are two ways to associate a DBFAWK file with a shapefile:  
signature-based, or per-file based.  

"signature-based" looks at the list of attributes in the dbf file and tries to 
apply a "one-size-fits-all" set of rules to all files that match the 
signature.  These dbfawk files all live in /usr/local/share/xastir/config,
and have somewhat descriptive names.  The two that are used for the TIGER/Line
data are "tgr2shp.dbfawk" and "tgr2shppoly_2006.dbfawk".  The first is for
the polyline data, the second is for the polygon data.

The second way to do this is per-file, so that each individual file can be
treated differently.  These files all live in the same directory as the 
shapefile, and have base names that are the same as the shapefile to which they
apply, but with the ".dbfawk" suffix instead of ".shp" or ".dbf"  A per-file
dbfawk file overrides any signature-based file that matches, and applies only
to the file whose name it matches.  

So if you want to experiment on one county you can copy the global default
file (tgr2shp or tgr2shppoly_2006, depending on what you want to change) into 
a per-file dbfawk file that matches that county's name and lives in the same 
directory as the county shapefile, and then when you're done you could move it 
to /usr/local/share/xastir/config and it would become a signature-based file.  
But be careful, because re-installing xastir will re-install the default 
tgr2shp and tgr2shppoly_2006 files.  You'll have to preserve your changes
somehow so they don't constantly get overwritten when you upgrade xastir.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick