An isosurface of a scalar function 
is a level set 
for a fixed value
. If 
is a smooth function with
continuous derivatives of all orders, then at points
where its gradient is nonzero,
the implicit function theorem makes the
isosurface a smooth surface whose normal direction is
.
Isosurface
See also
Gradient, Level Set, SurfaceExplore with Wolfram|Alpha
References
Lorensen, W. E. and Cline, H. E. "Marching Cubes: A High Resolution 3D Surface Construction Algorithm." Comput. Graphics 21, 163-169, 1987.Cite this as:
Weisstein, Eric W. "Isosurface." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Isosurface.html