[Talk-us] Updating unchanged TIGER imports to TIGER 2013
geodesy99 at gmail.com
Sat Mar 16 17:37:13 UTC 2013
> The other thing that has come up is that there are a lot of TIGER edges that
do not correspond to OSM ways in either their old or new version In Indiana
most of these seem to be linear water. Were these intentionally excluded
from OSM? Or would it be useful to try to pick them up as part of the set
of changes representing additions to TIGER between 2006 and 2013?
Hydrography features and attributes are available by county in the
Area Hydrography County-based Shapefile
Linear Hydrography County-based Shapefile
The Area Hydrography Shapefile contains the geometry and attributes of both
perennial and intermittent area hydrography features, including ponds,
lakes, oceans, swamps, glaciers, and the area covered by large streams
represented as double-line drainage. Single-line drainage water features
can be found in the All Lines Shapefile and Linear Hydrography Shapefile.
The Linear Hydrography shapefile contains all linear hydrography features
with “H” (Hydrography) type MTFCC in the MAF/TIGER database by county. The
shapefiles are provided at a county geographic extent and in linear
elemental feature geometry. The content of the linear hydrography shapefile
includes streams/rivers, braided streams, canals, ditches, artificial paths
and aqueducts. A linear hydrography feature may include edges with both
perennial and intermittent persistence.
The artificial path features may correspond to those in the USGS National
Hydrographic Dataset (NHD). However, in many cases the features do not
match NHD equivalent feature and will not carry the NHD metadata codes.
Single-line drainage water features include artificial path features that
run through double-line drainage features such as rivers and streams, and
serve as a linear representation of these features. Shorelines for area
hydrography can be found in the All Lines shapefiles with MTFCC set to
either “P0002” (shoreline of perennial water feature) or “P0003” (shoreline
of intermittent water feature).
> I believe TIGER water features were excluded because NHD data is more accurate
and comprehensive in most locations.
Somewhere else in the processing steps documentation, they mention that
they simplify and adjust either, or both, to eliminate braiding, etc., (
like where a winding road follows a oxbowed river) - and that adjustment is
tempered if either or both according to the significance as statistical
area boundary between census periods.
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