Extrema of a PointCloud surface

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Memo Remo 2020-6-18

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评论： Memo Remo 2020-6-20

采纳的回答： darova

Map.txt

Hi,

I have a set of data points in 3D space (a matrix of (n x 3), in which each row corresponds to a point) that are extracted from a stl file and all together describe an irregular surface. I want to find the extrema of this surface. Is there anyway to do this in matlab? Attached is a sample file.

I know using the approach described in the following post we can find the extrema but the problem is that my data points are not continous and I cannot use meshgrid.

https://www.mathworks.com/matlabcentral/answers/277512-how-to-find-peaks-in-3d-mesh

Thanks.

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darova 2020-6-19

Can you calculate normal vector of each face? Find vector v = [0 0 1]

Memo Remo 2020-6-19

Thanks Darova,

I think I should be able o do that. However, it is not very easy to do so.

You mean I should search for those locations that has minimum variations in the direction of the normal vector?

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darova 2020-6-20

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编辑：darova 2020-6-20

Here is the idea:

use griddata to build a surface
use imregionlmax to calculate extrema

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Memo Remo 2020-6-20

Great!

"griddata" was the function I was looking for.

Thanks!

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