[gdal-dev] SDTS

[Ben Discoe]

Thanks to your help so far! I've made a lot of great progress.

The current problem is with getting information out of SDTS DLG with OGR.

In the "classic" DLG representation, there are "nodes" which are connected
by "lines". The "lines" connect the nodes, not only via an array of points,
but they also reference the start and end nodes by index.

Using OGRLineString in the "Line String" layer, i can get the array of
points for each line. But, i cannot figure out how to tell which are the
start and end nodes.

I tried iterating through the OGRFieldDefn for these features, but none of
them contain the node information.

I could try doing a manual lookup of start and end nodes, by comparing the
(x,y) values at the ends of the lines... but is there a way to get the
information directly, as one does from a normal DLG?

Thanks,
Ben

> -----Original Message-----
> From: Frank Warmerdam
> Subject: Re: [gdal-dev] SDTS
>
>
> if I run ogrinfo against a 1:24000 DLG I get:
>
> warmerda at gdal[176]% ogrinfo -ro HP01CATD.DDF
> INFO: Open of `HP01CATD.DDF'
> using driver `SDTS' successful.
> 1: AHPF (None)
> 2: AHPT (None)
> 3: AHDR (None)
> 4: NP01 (Point)
> 5: NE01 (Point)
> 6: NA01 (Point)
> 7: NO01 (Point)
> 8: LE01 (Line String)
> 9: PC01 (Polygon)
>
> Of these layers, the first three (with geometry type None) are
> pure secondary attribute tables. You will find the Point, Line
> String and Polygon layers have geometry.