[Xastir-dev] Re: Tiger 2003 Polygons?

[Curt, WE7U]

On Thu, 21 Oct 2004, Tom Russo wrote:

> Already tweaked the dbfawk file a little, because I forgot to add the bit
> that would color water features that haven't been assigned landmark records,
> but still have WATER=1 or WATER=2 in the PIP record.
>
> Here ya go.  Last bit for the night.

You've been kind of busy.  Sorry you didn't get much sleep, hi hi.

I tried using the lastest script and dbfawk file this morning.  I
saw water, which is a big improvement!  I'll leave that Shapefile
conversion stuff to you at this point.

Regarding OGR/reading in raw Tiger files, I've been doing some
reading (and getting way lost) plus looking at the Python script.
It looks like I can read in the "Polygon" and "PolyChainLink" layers
first, caching the important data from them, then when I start
reading in the "CompleteChain" layer I can set aside the geometries
for those whose POLY_ID's match.  After I draw all of the
points/lines, I can draw the polygons using the cached values.

Advantage:  Fast, as I only have to read in the "CompleteChain"
layer once.

Disadvantage:  I'll end up with water on top of road/railroad
bridges and the like.

Another option would be to read in and cache the complete chain,
construct/display the polygons, then draw the rest of the vectors.
Might take a lot of memory to do this though.

Anything I'm missing, or do I have the rough idea now?  I'm looking
for both the minimal "correct" way to do it and the fastest method.
It'd be nice to snag the "inside" lat/long point for the polygon as
well, so I'd have a nice place to attach a label.  That info is in
those Tiger files as well.

--
Curt, WE7U			         http://www.eskimo.com/~archer
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