RANSAC shape detection, detecting many cylinders.

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Shukhrat
Posts: 12
Joined: Sun Mar 31, 2019 11:11 pm

RANSAC shape detection, detecting many cylinders.

Post by Shukhrat »

Hello,

I am trying to use RANSAC shape detection plugin to detect downed dead wood and trunk of tree (1 m above ground) using cylinder algorithm. I have one hectare plot with TLS point cloud, cut 1.3 m above ground in order to detect dead wood. I would like to use cylinder shape detection to extract cylinder shape features such as dead wood and trunk of trees. However, this algorithm is detecting only 20-30 cylinders which each of them include many dead wood and trunks. Changing parameters such as max distance to primitive, sampling resolution doesn't help.
Is there any way to detect many cylinder shaped features from point cloud?
Any help highly appreciated.

Cheers,
Shukhrat
daniel
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Re: RANSAC shape detection, detecting many cylinders.

Post by daniel »

Have you reduced the minimum number of samples (points) per primitive?
Daniel, CloudCompare admin
Shukhrat
Posts: 12
Joined: Sun Mar 31, 2019 11:11 pm

Re: RANSAC shape detection, detecting many cylinders.

Post by Shukhrat »

Thank you so much, it worked after several attempts. Sorry I was in the field which is why I didn't respond. Segments are created now, but still not perfect. For instance one cylinder can include 2-3 segments, could you please tell me the way to improve it ? Also, I now have a lot of vertical and horizontal cylinders, is it possible to select horizontal ones?

Thanks,

Kind regards,
Shukhrat
daniel
Site Admin
Posts: 7709
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
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Re: RANSAC shape detection, detecting many cylinders.

Post by daniel »

Hum, even if's already quite powerful, this algorithm produces a lot of false detections... And parameters can be tricky to set.

Currently there's no tool in CC that can do the cleanup automagically.You would have to change the code / develop new tools to do it.
Daniel, CloudCompare admin
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