what is manifold and non-manifold surface

OpenGL
1

as the subject.

can someone explain these two concepts in plain english? i have check out the wikipedia but i got lost in half way of reading it.
so maybe guru other there can explain these two concepts with simple and clear statements.

thanks

2

This should clarify things :
http://wiki.aqsis.org/faq/index#what_is_risubdivisionmesh_non-manifold_error
http://www.ru.is/kennarar/hannes/useful/BlenderManual/htmlI/ch07.html#BSG.EDT.F.S68.1107

3

shortest description i’ve heard that i thought helped was that a manifold surface is one in which every edge is adjacent to two faces. i believe that property is necessary and sufficient.

e.g. a triangle is not a manifold surface - each edge is adjacent to a single face. a cube is a manifold surface. if you take one face away from the cube, it is no longer manifold.

some properties that come out of this - no open boundaries (like the cube missing a face), the surface is “air-tight”, it has a distinct inside and outside surface, etc.

non-manifold is any surface that doesn’t meet the requirement for a manifold surface.

4

Basically, a manifold surface is a surface that completely encloses a volume.