
Geometry : 
Subject: Re: [geometry] Douglas Peucker on 3D lines
From: Stephan Menzel (stephan.menzel_at_[hidden])
Date: 20120620 08:33:02
Hi Barend,
thanks for the fast reply!
On Wed, Jun 20, 2012 at 11:58 AM, Barend Gehrels <barend_at_[hidden]> wrote:
> I will find this out later. Indeed this is unexpected so I think it is a too
> strict assertion somewhere.
Sorry I didn't append a testcase but the code I have given should be
enough. By judging from the templates I saw I suppose this would be
more or less compiler independent.
>> I have tried several PointSegmentDistanceStartegies, this was the only
>> one that compiled. The others threw plenty of errors at me as soon as
>> I got their headers included (MSVC2008). Are they different in what
>> they do or only in complexity and cost? In other words: Can I just use
>> that one that did compile or is in in some way worse than the others?
>
>
> This is the correct one indeed. Which more are there (for Cartesian?) I
> think for Cartesian there is only one included? For Spherical there are two
> (indeed redundant, have to be cleaned).
Well, frankly math is not my speciality (which is why I appreciate a
library taking care of it ;)
so I didn't know there's only one of them suitable. I was just looking
at the strategies and picked one at random. Sorry for not mentioning
just how ignorant I really am.
> I need a drawing to explain it well.
>
> So on this page:
> http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm
>
> in the figure on the right, marked with "1". You see an "a", "b", "c" there.
> If "b" > max.distance it will be included. If "b" < max.distance, it will
> not be included in the resulting linestring.
Ah, yes. Much clearer now. I took that totally wrong then.
Thanks for your help.
Cheers,
Stephan
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