Removing Points C++

Question

I have N number of points (x_N,y_N,z_N) in a point cloud. The point cloud forms the shape of a spherical shaped object. My problem is that I have points in my cloud that stick out noticeably along the z-axis (This is due to pin object inserted in my object during a scan). I would like to remove these points.

One approach I have taken is finding the change in slope for a set of points in my cloud compared to the immediate next set of points. (for example, I take my first 10 points, compute the change in slope and compare it to the change in slope for the next ten points). But this is not working so well. Any suggestions?

Any help would be greatly appreciated. Any confusion towards my problem, just let me know.

Answer 1

• Find the highest point in z, which is 100% sure to be a pin or apart of one.
• Set point to be center of sphere and remove all points within chosen radius
• Iterate twice more for other pins

Answer 2

If it's sure to be a sphere like object and points are equally spread (no side has more points than other side), take the average X, Y and Z of all points. This will be next to the center of the sphere. If that pin is not very thick or very long (if it have few points compared to the total), you can assume this as the center.

Then, measure the distance of each point to the center. Take off those having distances higher than the average distance.

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If you know the radii of the sphere and its center, simply calculate the distance of each point to the center and compare to the radii.

Answer 3

I have an observation and a corresponding suggestion:

First, the observation: You appear to be building a custom solution for a one-off case. This will not work when you scan a different object (with the pin sticking out again).

Now, the suggestion: Use something like meshlab, where you can load up a point cloud, select points and delete them.

Of course, if you're ken on writing code to solve this problem, then this is not helpful.