2011/11/20 José Luis García Pallero <jgpall...@gmail.com>:
> 2011/11/20 Juan Pablo Carbajal <carba...@ifi.uzh.ch>:
>> 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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>>> contains a definitive record of customers, application performance,
>>> security threats, fraudulent activity, and more. Splunk takes this
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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.
>
> Hi Pablo,
>
> The OctCLIP has only one function for performs general polygon
> clipping using the Greiner-Hormann algorithm (see
> http://davis.wpi.edu/~matt/courses/clipping/). I see that the geometry
> package is the Octave implementation of MatGeom for MatLab that has
> one function for polygon clipping when the clipper polygon is a
> rectangular box and the clipped one is convex. The Greiner-Hormann
> algorithm can work with general polygons so it could be used in the
> clipping function in geometry. I see too that this function is not
> implemented in the geometry package. But I would like to maintain
> alive the OctCLIP package because for me is easier to maintain
>
> --
> *****************************************
> José Luis García Pallero
> jgpall...@gmail.com
> (o<
> / / \
> V_/_
> Use Debian GNU/Linux and enjoy!
> *****************************************
>
I see your point. I can suggest the following courses of action:
1. You accept to be a maintainer of the geometry package (which indeed
is an extension of MatGeom since it handles piecewise polynomial
polygons http://octave.sourceforge.net/geometry/function/shapetransform.html)
and we merge the two packages. Geometry accepts a sub-folder
structure, therefore you will continue maintaining ONLY the octCLIP
folder. I can take care of the merging if you accept this proposal.
2. Geometry can add a wrapper that calls your function. This is clean
but has the drawback that the user needs to install more packages and
the dependency list grows.
I strongly suggest 1. However I do not want you to feel that geometry
is assimilating your package (we are not the Borg!). Geometry will be
your package and your package will be everything else that geometry
has. We will just clean up a little the repository and strengthen our
packages.
Looking forward to your answer.
--
M. Sc. Juan Pablo Carbajal
-----
PhD Student
University of Zürich
http://ailab.ifi.uzh.ch/carbajal/
------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure
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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