This paper deals with an overview and analysis of methods for inspecti
ng surface quality. The overview is done by a new classification based
on common mathematical concept yielding four groups of methods. First
, techniques based on curvature, such as colour-coded map, lines of cu
rvature, isolines of curvature, and focal surfaces are considered. The
y are followed by methods based on illumination models like isophotes,
Iv-curves, reflection lines, highlight lines, and shaded-image render
ing. Then, methods using special linear transformations are included:
polar and orthonomic surfaces. The final methods studied are contour l
ines. At the end, the results of a comparative analysis of all conside
red methods, such as their suitability for determining continuities, i
nflection points, and convex/concave regions, their speed, sensitivity
to surface changes, and invariance to geometric transformations, whic
h could be very interesting and useful for a user, are presented.