I'm not knowledgeable enough about shape files to be able to figure out what the "where" clause should be.
What I would like to do is pull parts of the shape files into their own file, so I would have a file (probably still keeping it broken down by state/county) for Limited Access Roads, another for secondary roads, etc.; basically, the same breakdown that is done in the dbfawk files. Having each bit of information in a separate file would let me set the max zoom level for each file and thus prevent Xastir from reading data that I have no intention of displaying at the particular zoom level that I am at. So that's my end goal. With that in mind, can someone recommend tools that would help me understand how to build appropriate where clauses to break these files out? Thanks! -- William McKeehan KI4HDU http://mckeehan.homeip.net On Mon, April 20, 2009 9:38 am, Tom Russo wrote: > On Mon, Apr 20, 2009 at 07:35:50AM -0400, we recorded a bogon-computron > collision of the <[email protected]> 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 > _______________________________________________ > Xastir mailing list > [email protected] > http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir > > _______________________________________________ Xastir mailing list [email protected] http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
