Roughness of 3D Surface

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Matheus de Lorenzo
Matheus de Lorenzo on 21 Sep 2021
Edited: Bjorn Gustavsson on 24 Sep 2021
Hello everyone,
I would like to calculate the salience (or roughness) from a 3D object recovered from spacial cordinates (x,y,z) cloud. The data represents a closed 3D rough surface object, meaning that the noise/roughness is not unique to the z component, so it cannot be represented just as a projected z(x,y) surface. It is a true closed shell data set in euclidian space.
The objective is to watermark zones where there would be high local noise value. I've done this with z(x,y) surfaces, but I could not find, at first, if there are any efforts in that direction within the community.
If anyone have pointers regarding this assessment I thank you in advance !
  2 Comments
KSSV
KSSV on 21 Sep 2021
Any pictorial example?
Matheus de Lorenzo
Matheus de Lorenzo on 21 Sep 2021
Edited: Matheus de Lorenzo on 23 Sep 2021
Hello, not a matlab imaging, but here there are two images of the same surface. The one on the left is meshed in such a way that the data can be represented as a z(x,y) function, while the one on the right is a true 3D convex surface where if we tried to do a z(x,y) function we would have more than one point in z present for the same (x_i, y_i) plane coordinate (and other projection losses). The characterization of roughness of the case on the right is on point to what I am looking for.

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Accepted Answer

Bjorn Gustavsson
Bjorn Gustavsson on 22 Sep 2021
Edited: Bjorn Gustavsson on 22 Sep 2021
There are a number of hits returned when searching for "curvature" on the file exchange. The gptoolbox seems to have a bunch of tools for topographical(topological?) tasks. Some might be useful for your task. Perhaps this one: curvature-estimationl-on-triangle-mesh - if you have a general surface you ought to be able to approximate it with a triangle-mesh (not topology-general, but "every-day general"...)
HTH
  10 Comments
Bruno Luong
Bruno Luong on 24 Sep 2021
Edited: Bruno Luong on 24 Sep 2021
???? differ to what?
The roughness is measured by an probe that scan (x,y) and for each position the probe measure the heigh z(x,y). The roughness is derived from the data z(x,y) and intended to be used to access the quality/characteristics of the polishing subject by surface such as optical surface, tribology surface , etc.... It's an industry metrology standard, not a rigouruous math definition that defines for fancy surface like yours.
Bjorn Gustavsson
Bjorn Gustavsson on 24 Sep 2021
Edited: Bjorn Gustavsson on 24 Sep 2021
That is not lost on me.

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