To
recognize rapidly the pattern of an intersection of n cylinders the following
technique is useful.

- Draw the great circles on the
sphere of all cylinder axes.
- Use a 2-dimensional picture
- Apply the generalized angle
bisection method in each polygon

The *generalized
angle bisection method* is best described in the following picture

Start in
the corners and construct slightly curved lines. Consider also bisecting lines
of imaginary corners outside the polygon, which are formed of not immediate
neighbours of polygon sides.

Example

Great
circles:

Great
circles after application of the generalized angle bisection method in some
polygons.

Four facets
are appearing.