[Xastir] SDTS to shapefile conversion?

[Tom Russo]

On Mon, Jan 03, 2005 at 12:27:59PM -0800, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Mon, 3 Jan 2005, Gerry Creager n5jxs wrote:
> 
> > Fort those of you who followed the APRS Sig thread about Tiger
> > inaccuracies a couple of weeks or months ago, this is a significant
> > deal.  I may want to snag the shapefiles; I'll get ahold of the player
> > in NYC who was so concerned about the TigerLine files.  This should make
> > him happier.
> >
> > One caveat: It is my understanding from our USGS State Mapping
> > Coordinator that not all of the SDTS coverages have been appropriately
> > reprojected to NAD83.
> 
> I think the OGR code as used by Xastir will auto-convert, but you're
> saying that for OGR2OGR you'd perhaps have to have it do a datum
> translation as well as a file translation, in order to come out with
> Shapefiles that were in WGS84 or NAD83, right?

Yes, one would have to do the projection and datum shift when using 
shapefile conversions of sdts data.  ogr2ogr can do it in one step, so 
this isn't a problem.

> I'm basing my statement about Xastir/OGR doing the auto-translation
> on the fact that it does this with Shapefiles just fine, as long as
> they have a .prj file with them that OGR can recognize.  I've used
> state-plane coordinate system NAD27 shapefiles under OGR and it
> works.

If one wants to use Xastir/OGR to read shapefiles then one would need a .prj 
for the shapefiles.  ogr2ogr creates one.  But Jason wants to use the regular 
shapelib code so he has access to dbfawk to customize presentation, and 
therefore must do a conversion to WGS84 geographic.  

-- 
Tom Russo    KM5VY     SAR502  DM64ux         http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://www.qsl.net/~km5vy/
 "When life gives you lemons, find someone with a paper cut."