3D modelling and visualization based on general meshes needs a great
amount of memory demands. Regular grids can substantially decrease them.
Moreover, using the regular data structures results in efficient numerical
procedures and simplicity of algorithms. On the other hand, disadvantage
of regular grids is in lower flexibility of shape expression. One of the
possibilities how to improve the shape expression of a regular grid is
its decomposition to tetrahedra. The paper concerns the problem which
arises here -- nonconformity of decomposition.