Extract / grow a cluster given a point inside the cluster

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Extract / grow a cluster given a point inside the cluster

JTray
Hi all,

I am looking to extract / grow a cluster from a point cloud given a point
inside the cluster. In the point cloud there will be numerous clusters but
each will be separated by relatively large areas of space. I just want to
get one cluster if the user selects any point inside it.

I have looked at the examples but I can't see anything that allows me to
grow / segment a cluster based around a point

Is there an example / theory on how best to do this?

Thanks

JT



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Re: Extract / grow a cluster given a point inside the cluster

Fabien Rozar
Hi JT,

It seems you try to deal with a segmentation problem.
Did you read this link?

frozar

2018-06-08 13:59 GMT+02:00 JTray <[hidden email]>:
Hi all,

I am looking to extract / grow a cluster from a point cloud given a point
inside the cluster. In the point cloud there will be numerous clusters but
each will be separated by relatively large areas of space. I just want to
get one cluster if the user selects any point inside it.

I have looked at the examples but I can't see anything that allows me to
grow / segment a cluster based around a point

Is there an example / theory on how best to do this?

Thanks

JT



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Re: Extract / grow a cluster given a point inside the cluster

JTray
Hi Frozar,

Thanks for your reply

I found the function getSegmentFromPoint() which seems to do what I want.
The biggest problem is how slow the code is at computing the normals prior
to this call. If there a way to get a segment using a KDtree or Octree
method that would be much faster?

Thanks

JT



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Re: Extract / grow a cluster given a point inside the cluster

Fabien Rozar
Hi,

I know, the computation of normal vectors are slow. And if I remember correctly,
this method compute the segmentation of the whole point cloud. If you want to 
do an interactive segmentation where you click on a point to seed the region 
growing segmentation, it should be much faster.

I think you're right about the using of KDtree or Octree for segmentation.
I know this octree based segmentation:

Currently, this method is not available in PCL repository, but maybe soon...

Cheers,
frozar

Le lun. 11 juin 2018 à 10:20, JTray <[hidden email]> a écrit :
Hi Frozar,

Thanks for your reply

I found the function getSegmentFromPoint() which seems to do what I want.
The biggest problem is how slow the code is at computing the normals prior
to this call. If there a way to get a segment using a KDtree or Octree
method that would be much faster?

Thanks

JT



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Re: Extract / grow a cluster given a point inside the cluster

JTray
Thanks again for the advice Frozar. I'll do a little digging around and see
if I can come up with a quicker way to segment. I'm sure there is a better
way than I am currently doing it



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