[OSM-dev] OSM-dev] Determining if two linestrings are "similar"

Sandor Seres sandors39 at gmail.com
Mon Jan 7 11:31:06 GMT 2013

You may call it "similar" or "almost overlapping"  or ... probably meaning
that two polygons, poly-lines or poly-line segments are so close to each
other that they, with a very high probability; represent the same
real-world object.
There is a huge number of such cases in OSM source data producing
a proportional amount of redundancy. While this is not a serious problem in
raster mapping, it causes considerable problems and inefficiency in vector
mapping, or in vector streaming (especially via cellular networks) based
mapping. Therefore, many of us, preferring vector mapping, have certain
model for eliminating "almost overlapping" geometries in our
data-preparation-tool chain.
I am using a proprietary corridor-geo-search function where the
"almost"/"similar" notion is a variable corridor-thickness. A line-string
(as you call it) is the skeleton line to such a corridor. The function is
very fast and is (practically) in no-time eliminating huge amount of
For more details, please, do not hesitate to contact me.
Regards, Sandor.
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