[Talk-us] Using TIGER to find missing road segments in OSM after license change

Martijn van Exel m at rtijn.org
Fri Mar 30 15:51:27 BST 2012

Hi all,

On Thu, Mar 29, 2012 at 12:32 PM, Martijn van Exel <m at rtijn.org> wrote:

> [...]
> The main problem I found with the original query is the Haussdorff
> distance parameter, which chosen so small would not catch TIGER ways and
> OSM ways that are of very different length. I increased the distance
> threshold by a factor 10 but still get about 38000 candidates for missing
> roads based on this query (doing a select * from tigerlines where gid not
> in ....). But maybe I'm overlooking something else altogether in this. More
> complex queries tend to be overwhelming to me. Maybe I'm not using the
> right TIGER source file? I picked the all lines one.
> Ont of the main problems with matching TIGER to OSM is the varying line
length which will make any match on geometric closeness likely to fail. A
way to make alleviate this is to:
a) merge all OSM and TIGER ways that comprise two seperate (oneway)
roadways. Never done that before but seems possible. Then,
b) merge all line features that have the same name into one linestring.
Never done that before either and presents some pitfalls (non-contiguous
ways). Coudl use MULTILINESTRING?

Then run the match query.

Ideas on how to implement / improve this idea?

martijn van exel
geospatial omnivore
1109 1st ave #2
salt lake city, ut 84103
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