2011/11/20 José Luis García Pallero <jgpall...@gmail.com>:
> 2011/11/20 Carnë Draug <carandraug+...@gmail.com>:
>> On 19 November 2011 00:40, Tobias Andersson <xyzto...@hotmail.com> wrote:
>>> First of all, hi everyone! I'm new here and hope that this is the right way
>>> to post bug reports. Otherwise, please inform me how to do it.
>>> Now, I installed octclip to find intersections between polygons and found an
>>> odd behaviour when sections of different polygons follow the same line.
>>> Also, Strange results are returned when a section "touches" a point in the
>>> other polygon.
>>> The problem is that the result in the first example should be one polygon
>>> and that the result in the second example should be a polygon without the
>>> duplicate point [2.4 2.4].
>>> I thank you for updating the package or advising me if I think wrong on how
>>> the functionality should be.
>>>
>>>
>>> Two example codes are shown below so that you can rerun the script
>>> yourselves:
>>> 1. Sections of different polygons follow the same line:
>>> % This is a script to generate a polygon and plot it in a figure and find
>>> intersection
>>> polygons(1).p = [ 2.2 2.2;
>>> 3.4 3.4;
>>> 6.3 3.4;
>>> 5.3 2.8;
>>> 3.3 2.4];
>>> polygons(2).p = [ 1.2 2.2;
>>> 3.4 3.4;
>>> 5.3 3.4;
>>> 5.3 2.8;
>>> 4.4 2.3;
>>> 3.3 1.7]+5;
>>> polygons(2).p = polygons(2).p + [1*ones(size(polygons(2).p,1),1)
>>> 0*ones(size(polygons(2).p,1),1)];
>>> plot(polygons(1).p(:,1),polygons(1).p(:,2),'*-');
>>> hold on
>>> plot(polygons(1).p([end 1],1),polygons(1).p([end 1],2),'*-');
>>>
>>> plot(polygons(2).p(:,1),polygons(2).p(:,2),'*-.k');
>>> plot(polygons(2).p([end 1],1),polygons(2).p([end 1],2),'*:k');
>>> hold off
>>> [X,Y,nPol,nInt,nPert] = _oc_polybool(polygons(2).p,polygons(1).p,'AND');
>>> fprintf('runPolygonShowNonIntersecting.m\n')
>>> fprintf('Numbers of polygons found: %i\n',nPol)
>>>
>>>
>>> 2. A section "touches" a point in the other polygon:
>>> % This is a script to generate a polygon and plot it in a figure and find
>>> intersection
>>> polygons(1).p = [ 2.2 2.2;
>>> 3.4 3.4;
>>> 6.3 3.4;
>>> 5.3 2.8;
>>> 3.3 2.4];
>>> polygons(2).p = [ 1.2 2.2;
>>> 3.4 3.4;
>>> 5.3 3.4;
>>> 5.3 2.8;
>>> 4.4 2.3;
>>> 3.3 1.7]+0.2;
>>> polygons(2).p = polygons(2).p + [1*ones(size(polygons(2).p,1),1)
>>> 0*ones(size(polygons(2).p,1),1)];
>>> plot(polygons(1).p(:,1),polygons(1).p(:,2),'*-');
>>> hold on
>>> plot(polygons(1).p([end 1],1),polygons(1).p([end 1],2),'*-');
>>>
>>> plot(polygons(2).p(:,1),polygons(2).p(:,2),'*-.k');
>>> plot(polygons(2).p([end 1],1),polygons(2).p([end 1],2),'*:k');
>>> hold off
>>> [X,Y,nPol,nInt,nPert] = _oc_polybool(polygons(2).p,polygons(1).p,'AND');
>>> fprintf('runPolygonShowNonIntersecting.m\n')
>>> fprintf('Numbers of polygons found: %i\n',nPol)
>>
>> Hi Tobias
>>
>> do you think you can submit a patch? Anyway, I'm also sending this
>> e-mail to the dev who wrote this function, he's probably the best
>> person to fix anything about the package.
>>
>> Carnë
>>
>
> Hello,
>
> Tobias, I don't understand when you say that in the first example the
> result should be one polygon. You perform the 'AND' operation but the
> two polygons in your example are disjoints, so they have no
> intersection. The second example runs well for me. Please, see the
> attached *.png files with the results of your examples in my computer
> (in the second one I have added in red the resulting polygon).
>
> Take in account too that I implement the Greiner-Hormann algorithm
> which is not robust when a point or an edge of one polygon coincides
> with a point or an edge of the other. Please, see
> http://davis.wpi.edu/~matt/courses/clipping/ for more details.
>
> About OctCLIP, you should use the oc_polybool function (is a *.m
> script) instead of the _oc_polybool one (is the *.oct function)
>
> Cheers
>
> --
> *****************************************
> José Luis García Pallero
> jgpall...@gmail.com
> (o<
> / / \
> V_/_
> Use Debian GNU/Linux and enjoy!
> *****************************************
>
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Hi all,
The geomtry package also has functions to deal with polygons in 2D.
Is there a chance that we merge the octclip and geometry package?
At least it would be good to know what is already implemented in both
packages and if possible benchmark them.
Thanks
--
M. Sc. Juan Pablo Carbajal
-----
PhD Student
University of Zürich
http://ailab.ifi.uzh.ch/carbajal/
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contains a definitive record of customers, application performance,
security threats, fraudulent activity, and more. Splunk takes this
data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
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