[scikit-image] Whar are values returned by measure.marching_cubes

[EV Petr]

Hello,

I'm not familiar with scikit-image. I  only want to use the function
`measure.marching_cubes`,
but I cannot figure out what really represent the values returned by it.

`help(measure.marching_cubes)` says:

*values : (V, ) array*

*Gives a measure for the maximum value of the data in the local region
        near each vertex. This can be used by visualization tools to apply
        a colormap to the mesh.*


What is data here (this term is too general)?

I saw that values.shape[0] is the same as vertices.shape[0]. Hence
each value is associated to a vertex.

 How is it assigned to a vertex? How are these values related to the
volume or to the equation F(x,y,z)=0?

(I want to extract a triangulation of an implicit surface having this equation).


A second question is related to the coordinates of vertices.

When I plot the  trisurf defined by `vertices` and `faces` I notice

that the x, y and z-range illustrated by tick values

is different from the real values. More precisely: if my surface has
zmin=-1 and zmax=2,  on z-axis

this range is [5,11].  Is there a transformation that maps the
vertices coordinates, as they are returned by

`measure.marching_cubes` to real coordinates on my surface?


Thanks,


Eve
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