Am 13.07.2012 10:13, schrieb Paul Norman:
From: nimix [mailto:[email protected]]
Sent: Friday, July 13, 2012 12:58 AM
To: [email protected]
Subject: [OSM-dev] (Multi)Polygon handling


Frederik Ramm wrote

If we can't get everyone to use the same code base, then it would at
least be great to reach some kind of agreement here, or maybe at least
produce a test suite that everyone runs their code against.


I created a testsuite for that with some more cases that need special
treatment. Unfortunately I only stored the WKB representation in Google
mercator projection, so it is not very human readable. The testcase
contains a LINESTRING and a MULTIPOLYGON for simple closed ways and for
relations a MULTILINESTRING and a MULTIPOLYGON ([1]).

I would volunteer to bring it in an other format so that it is useful
for everyone writing converters and I would like to discuss what is the
best way to do it. I would suggest an .osm file and a Wiki Page
containing the expected results in WKT/WKB and some explanation for each
case. Any other ideas?
Best regards,
Melchior
My following of web standards has convinced me it is necessary to define the
expected output in every case, including invalid ones, or you will have
differing implementations. I've been giving it some thought as to what needs
to be tested, and I don't think it's excessive. I'd estimate 25-50 small
tests would cover everything.
+1
But it should be possible to reject false polygon models.
So to say:
- any application "must" deal with correct tagging in the same way (which is defined by the corresponding test cases) - if an application interprets wrong polygons, it "must" do it in the way which is defined by the corresponding test cases - but(!) every application is allowed to reject these polygons because of errors - any application is encouraged to report wrong polygons detected to users who may be able to fix that in the database.

("must" of course only to correctly claim "standard" osm polygon handling)

regards
Peter


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