CGAL users discussion list

[Kilian Demeulemeester <>]

Hello,

I took a closer look, our CMakeLists clones "releases/CGAL-4.10".

Therefore, the bug only no longer exists - except in my environment :(

Thanks for the responsiveness and the help.

Best.

Kilian Demeulemeester 
Directeur R&D  
Snapkin | Outil de mesure et de mise en plan 2D/3D pour le bâtiment.
Tél : +33 (0)7 83 49 82 36 | Discutons !


-----Message d'origine-----
De : 

 
<>
 De la part de Simon Giraudot
Envoyé : mardi 10 juillet 2018 11:00
À : 

Objet : Re: [cgal-discuss] Point Set Shape Detection - connected component do 
not provide expected results

Hello,

Are you sure you are using CGAL 4.10.2?

This bug has indeed existed but it was fixed in CGAL 4.10.1: 
https://github.com/CGAL/cgal/pull/2194

Best,

-- 
Simon Giraudot, PhD
R&D Engineer
GeometryFactory - http://geometryfactory.com/



Le 10/07/2018 à 10:10, Kilian Demeulemeester a écrit :
> Good morning,
>
> I managed to identify the bug in the RANSAC class. It can be described in 
> this way:
>
> During the detect method, the process is as follows:
> 1. Candidates are generated
> 2. Among the generated candidates, the best of them is extracted: 
> best_candidate - that we will name SHAPE1
> 3. The connected_components method is called on SHAPE1, and the value of 
> m_has_connected_component changes to true.
> 4. For the bug to occur, we assume that SHAPE1 meets the minimum number of 
> inliers condition BUT the stop_probability associated with SHAPE1 is not 
> sufficient for it to be extracted.
> 5. From then on, the loop starts again at step 1.
> 6. After studying more candidates, SHAPE1 is again the best candidate.
> 7. HOWEVER, during the call of score method, THE VALUE OF SHAPE1 m_indices 
> HAS BEEN MODIFIED.
> 8. As in step (3), the connected_components method is called on SHAPE1. 
> However, since m_has_connected_component is already a true, the value of 
> m_indices IS NOT MODIFIED. Therefore, the largest connected_component is 
> not extracted.
> 9. As in step 4, the stop_proability value associated with SHAPE1 is 
> calculated. Let's just say this time it's enough to extract the candidate. 
> Then, the inliers are extracted. Unfortunately, these do not correspond to 
> good inliers.
>
> My idea is to fix the score method as so: when this method is called, the 
> value of m_has_connected_component should be set to false BECAUSE IT 
> CHANGES THE value of m_indices.
>
> In order to fix the bug locally (monkey patching), I've override the 
> connected_component method so that it keeps m_has_connected_component to 
> false. By doing so, the bug was fixed.
>
> If my description seems clear, can I open a merge request to correct the 
> `score` method? It would be for me the opportunity to contribute (in a tiny 
> way) to the project :)
>
> Best.
>
> Kilian Demeulemeester
> Directeur R&D
> Snapkin | Outil de mesure et de mise en plan 2D/3D pour le bâtiment.
> Tél : +33 (0)7 83 49 82 36 | Discutons !
> 
>
> -----Message d'origine-----
> De : Kilian Demeulemeester
> Envoyé : lundi 9 juillet 2018 15:17
> À : 
> 
> Objet : RE: [cgal-discuss] Point Set Shape Detection - connected component 
> do not provide expected results
>
> Hello,
>
> The following snippet proves the bug (in my environment):
> https://gitlab.com/snippets/1731486
>
> The part about loading the point cloud and writing down the point cloud 
> have to be rewritten (because I'm using my company custom library).
>
> The code provided in the snippet detects 343 shapes - most of them being 
> not "connected".
>
> Best.
>   
> -----Message d'origine-----
> De : 
> 
>  
> <>
>  De la part de Kilian Demeulemeester Envoyé : lundi 9 juillet 2018 11:44 À 
> : 
> 
>  Objet : RE: [cgal-discuss] Point Set Shape Detection - connected component 
> do not provide expected results
>
> I'll try to create a snippet.
>
> The bugs occur with the parameters I've provided:
> - probability=0.01
> - minPoints=10000
> - epsilon=0.01
> - clusterEpsilon=0.05
> - normalThreshold=0.9
>
> It looks that the parameter minPoints is the one responsible for this 
> behavior.
>
> When using the default value, the extracted shapes are correct (but a lot 
> of them are missing).
>
> Best.
>
> Bien cordialement.
> Kilian Demeulemeester
> Directeur R&D
> Snapkin | Outil de mesure et de mise en plan 2D/3D pour le bâtiment.
> Tél : +33 (0)7 83 49 82 36 | Discutons !
> 
>
> -----Message d'origine-----
> De : 
> 
>  
> <>
>  De la part de Simon Giraudot Envoyé : lundi 9 juillet 2018 10:53 À : 
> 
>  Objet : Re: [cgal-discuss] Point Set Shape Detection - connected component 
> do not provide expected results
>
> Hello,
>
> I am sorry but I cannot reproduce your bug. Does it happen all the time?
> RANSAC being based on randomness, it's possible that the result changes 
> from one run to another. Do you have the (x,y,z) coordinates of where this 
> bug happens?
>
> Also, there are no normal vectors in the file you provide. Can you tell me 
> how you estimate these normals? Better, can you share the source code of 
> how you estimate the normals + call RANSAC (maybe just the section of the 
> code if it is part of a larger project)? That way, I am sure I'm doing the 
> same thing.
>
> Best,
>
>
> --
> Simon Giraudot, PhD
> R&D Engineer
> GeometryFactory - http://geometryfactory.com/
>
>
>
> Le 09/07/2018 à 10:02, Kilian Demeulemeester a écrit :
>> Hello,
>>
>> Here is the point cloud in PLY format:
>> https://drive.google.com/file/d/1cPcxFLQCccmd2X1OWzunc0WtRIiuM9f0/view
>> ?usp=sharing
>>
>> Best,
>>
>> Bien cordialement.
>> Kilian Demeulemeester
>> Directeur R&D
>> Snapkin | Outil de mesure et de mise en plan 2D/3D pour le bâtiment.
>> Tél : +33 (0)7 83 49 82 36 | Discutons !
>> 
>>
>> -----Message d'origine-----
>> De : 
>> 
>>  
>> <>
>>  De
>> la part de Simon Giraudot Envoyé : lundi 9 juillet 2018 09:27 À :
>> 
>>  Objet : Re: [cgal-discuss] Point Set Shape
>> Detection - connected component do not provide expected results
>>
>> Hello,
>>
>> Le 06/07/2018 à 15:33, Kilian Demeulemeester a écrit :
>>> The point cloud is available here: 
>>> https://drive.google.com/open?id=1r4-9vLq35L6c4SwlGvqppzv6-wrP8nfV 
>>> (108Mo).
>> I can't seem to open E57 files, could you convert your point cloud to
>> another format? (PLY, OFF, LAS, XYZ.)
>>
>> Thank you,
>>
>> --
>> Simon Giraudot, PhD
>> R&D Engineer
>> GeometryFactory - http://geometryfactory.com/
>>
>>
>>> We are using CGAL 4.10.2.
>>>
>>> I've seen that there has been changes relative to that package but... 
>>> nothing related to this.
>>>
>>> I've checked the release note and didn't see anything related to that bug.
>>>
>>> I've also blamed the changes of the method connected_component in 
>>> CGAL\Shape_detection_3\Shape_base.h - and did not find any changes lately.
>>>
>>> As for now, I think I will try to extend the class 
>>> CGAL::Shape_detection_3::Plane<Traits> to create my own version - and 
>>> overload the connected_component method to use our own version (using 
>>> opencv).
>>>
>>>
>>> Bien cordialement.
>>> Kilian Demeulemeester
>>> Directeur R&D
>>> Snapkin | Outil de mesure et de mise en plan 2D/3D pour le bâtiment.
>>> Tél : +33 (0)7 83 49 82 36 | Discutons !
>>> 
>>>
>>> -----Message d'origine-----
>>> De : 
>>> 
>>>  
>>> <>
>>>  De
>>> la part de Simon Giraudot Envoyé : vendredi 6 juillet 2018 15:04 À :
>>> 
>>>  Objet : Re: [cgal-discuss] Point Set Shape
>>> Detection - connected component do not provide expected results
>>>
>>> Hello,
>>>
>>> This is indeed unexpected. From what you explain in your email, I don't 
>>> think you did anything wrong, so I suspect there is a bug in the package. 
>>> What version of CGAL do you use? There has been some changes in the Shape 
>>> Detection package lately (but if I remember correctly, nothing that 
>>> addresses a bug like this one).
>>>
>>> Is there any way you could you share the point cloud so I can try to 
>>> reproduce it and find where is the bug?
>>>
>>> Best,
>>>
>>> --
>>> Simon Giraudot, PhD
>>> R&D Engineer
>>> GeometryFactory - http://geometryfactory.com/
>>>
>>>
>>> Le 06/07/2018 à 10:16, KDemeul a écrit :
>>>> Hello,
>>>>
>>>> I am trying to use the  Point Set Shape Detection
>>>> <https://doc.cgal.org/latest/Point_set_shape_detection_3/index.html#
>>>> Chapter_Point_Set_Shape_Detection>
>>>> package - in order to detect PLANEs only.
>>>>
>>>> I've defined the value of the parameters as follow:
>>>> -probability=0.01
>>>> - minPoints=10000
>>>> - epsilon=0.01
>>>> - clusterEpsilon=0.05
>>>> - normalThreshold=0.9
>>>>
>>>> However, it seems that the clusterEpsilon parameter is not correctly
>>>> taken into account.
>>>>
>>>> Here is an example of a plane detected by the algorithm.
>>>>
>>>> As one can see, the left part is disconnected from the right part -
>>>> by a gap of approx 1.6m.
>>>>
>>>> <http://cgal-discuss.949826.n4.nabble.com/file/t375977/Sans_titre.pn
>>>> g>
>>>>
>>>> Is there something I don't get?
>>>>
>>>> Best regards,
>>>>
>>>> Kilian Demeulemeester.
>>>>
>>>>
>>>>
>>>> --
>>>> Sent from: http://cgal-discuss.949826.n4.nabble.com/
>>>>
>>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to 
> https://sympa.inria.fr/sympa/info/cgal-discuss
>
>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to 
> https://sympa.inria.fr/sympa/info/cgal-discuss
>
>
>



-- 
You are currently subscribed to cgal-discuss.
To unsubscribe or access the archives, go to
https://sympa.inria.fr/sympa/info/cgal-discuss