# Roughness of 3D Surface

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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 !
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Matheus de Lorenzo on 21 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 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
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Bjorn Gustavsson on 24 Sep 2021
That is not lost on me.

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