[Xastir] New capability: 2008 Tiger Shapefile street maps

[Tom Russo]

On Mon, Apr 20, 2009 at 07:35:50AM -0400, we recorded a bogon-computron collision of the <mckeehan at mckeehan.homeip.net> flavor, containing:
> This is exactly the information that I was looking for, thanks!
> 
> One thing that I notice is that when I am at a zoom level that is out pretty
> far, like 768 or so, it takes a long time for Xastir to run through all of the
> maps. Much of the map data is repressed by the dbfawk files, but Xastir still
> has to process it.
> 
> Is there a way to break out each component from the files, then select max
> zoom on them in Xastir to allow Xastir to skip them at the file level?

Yes.  See "ogr2ogr" and the "-where" option.  ogr2ogr is part of GDAL.

You can use this tool to extract all the features of one type into a separate
file with the same signature as the original, so it will use the same dbfawk
file.  Then you can set map properties to your liking for each such file you
produce.

If you don't have GDAL installed and want a lighter-weight tool that can
extract features by attributes from a shapefile, see the trivial 
"split_shape_by_attribute.c" program in my "shape_web" site:  
 http://www.swcp.com/~russo/shape_web/

Follow the link for "Shapefile splitter."  The same section also has the syntax
for getting the job done with ogr2ogr.

The trick would be to construct a where clause that selects the right MTFCC
codes for the features you want.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
  In some cultures what I do would be considered normal. 
                                  -- Ineffective daily affirmation