How a face bends at one place: the point, the unit normal the way the face looks, the largest and
smallest curvatures (1 over a radius, positive where the face bulges out along its normal, as the
outside of a ball does), their mean and product (the Gaussian curvature), and the unit directions
along which the face bends most and least. isUmbilic is true where it bends the same way in every
direction, as a plane or a ball does; where no curvature can be read, isDefined is false and the
curvatures and directions are 0.
How a face bends at one place: the point, the unit normal the way the face looks, the largest and smallest curvatures (1 over a radius, positive where the face bulges out along its normal, as the outside of a ball does), their mean and product (the Gaussian curvature), and the unit directions along which the face bends most and least.
isUmbilicis true where it bends the same way in every direction, as a plane or a ball does; where no curvature can be read,isDefinedis false and the curvatures and directions are 0.