3D extrusion algorithm can be used for meshing prisms, i.e. <b>3D Shapes</b>
defined by two opposing faces having the same number of vertices and
-edges and meshed using the \ref projection_algos_page "2D Projection"
-algorithm. These two faces should be connected by quadrangle "side"
-faces.
+edges and meshed using, for example, the \ref projection_algos_page
+"2D Projection" algorithm. These two faces should be connected by
+quadrangle "side" faces.
The opposing faces can be meshed with either quadrangles or triangles,
while the side faces should be meshed with quadrangles only.
-\image html image157.gif
+\image html image157.gif "Prism with 3D extrusion meshing".
As you can see, the <b>3D extrusion</b> algorithm permits to build and to
have in the same 3D mesh such elements as hexahedrons, prisms and
polyhedrons.
-*/
\ No newline at end of file
+\note This algorithm works correctly only if the opposing faces have
+the same (or similar) meshing topography. Otherwise, 3D extrusion
+algorithm can fail to build mesh volumes.
+
+*/