Hi.
I just read on wikipeda the meaning of class surfaces a.
".. class a surface is a term used in the design jargon indicating a style surface, obtained from the union of multiple free-form surfaces, which presents continuity of tangency and curvature in correspondence of all edges of union... "
observation
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a class surface is composed of the union of elementary surfaces.
elementary surfaces are polynomials (*).
the typical elementary surfaces are: plane, sphere, paraboloid, ellipsoid, etc.
along the lines of fitting the surfaces have the same tangent plane (derived before) and same curvature (derived second).
my comment
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with class surfaces, you can model all surfaces of the world.
problems can arise if I have to shape a surface that has several spatial twists. In this case the surface will have many elementary surfaces and many fitting lines.
For what I have to do, class surfaces are more than adequate.
Hi.
enrico
(*)
plan is an order polynomial 1 in x, y, z variables
ball is an order polynomial 2 in x, y, z variables
ellipsoid is an order polynomial 2 in x, y, z variables