\page projection_algos_page Projection Algorithms
-\n Projection algorithms allow to define the mesh of a geometrical
+\tableofcontents
+
+Projection algorithms allow to define the mesh of a geometrical
object by the projection of another already meshed geometrical object.
+\note Source and target geometrical objects mush be topologically
+equal, i.e. they must have same number of sub-shapes, connected to
+corresponding counterparts.
+
+\image html topo_equality.png Topologically equal faces suitable for 2D projection.
+
+
+\section projection_1D Projection 1D
+
<b>Projection 1D</b> algorithm allows to define the mesh of an edge
(or group of edges)
by the projection of another already meshed edge (or group of edges).
\image html projection_1d.png
-In this menu you can define the \b Name of the algorithm, the already
-meshed source \b Edge and the \b Mesh (It can be omitted only when
-projecting a submesh on another one from the same global Mesh).
-It could also be necessary to define the orientation of edges,
-which is done by indicating the <b>Source Vertex</b> being the first point
-of the Source Edge and the <b>Target Vertex</b> being the first point of
-the created \b Edge.
+In this dialog you can define
+<ul>
+ <li> the \b Name of the algorithm,</li>
+ <li> the already meshed <b> Source Edge</b> and </li>
+ <li> the <b>Source Mesh </b> (It can be omitted only when projecting
+ a sub-mesh on another one of the same Mesh).</li>
+ <li> It could also be necessary to define the orientation of edges,
+ which is done by indicating the <b>Source Vertex</b> being the
+ first point of the <b>Source Edge </b>and the <b>Target Vertex</b> being
+ the first point of the edge being meshed.</li>
+</ul>
<br>
For a group of edges, <b>Source</b> and <b>Target</b> vertices should be
-shared by one edge of the group. If <b>Source</b> and <b>Target</b>
-vertices are specified, the elements of the group must be adjacent.
+shared by only one edge of the group. If <b>Source</b> and <b>Target</b>
+vertices are specified, the edges in the group must be connected.
The source and target groups must contain equal number of edges
and they must form topologically equal structures.
+\section projection_2D Projection 2D
+
\n <b>Projection 2D</b> algorithm allows to define the mesh of a face
-(or group of faces) by the
-projection of another already meshed face (or group of faces). This
-algorithm works only
-if all edges of the target face have been meshed as 1D Projections of
-the edges of the source face.
+(or group of faces) by the projection of another already meshed face
+(or group of faces). This algorithm works only if all edges of the
+target face have been discretized into the same number of
+segments as corresponding edges of the source face.
To apply this algorithm select the face to be meshed (indicated in the
field \b Geometry of <b>Create mesh</b> dialog box), <b>Projection
-2D</b> in the list
-of 2D algorithms and click the <em>"Add Hypothesis"</em> button. The
-following dialog box will appear:
+2D</b> in the list of 2D algorithms and click the <em> "Add
+Hypothesis"</em> button. The following dialog box will appear:
\image html projection_2d.png
-In this menu you can define the \b Name of the algorithm, the already
-meshed source \b Face and the \b Mesh (It can be omitted only when
-projecting a submesh on another one from the same global Mesh).
-It could also be necessary to define the orientation of mesh on the
-face, which is done by indicating two <b>Source Vertices</b>, which
-belong to the same edge of the source face, and two <b>Target
-Vertices</b>, which belong to the same edge of the created \b Face.
-For groups of face, they must contain equal number of faces
-and they must form topologically equal structures.
-
-\n <b>Projection 1D-2D</b> algorithm differs from <b>Projection 2D</b>
-algorithm in one aspect: it generates mesh segments on edges of
-the face according to the projected 2D elements; thus it does not
-require the edges to be meshed by any other 1D algorithm; moreover it
-does not allow to mesh edges of the face using another algorithm via
-definition of sub-meshes.
+In this dialog you can define
+<ul>
+ <li> the \b Name of the algorithm, </li>
+ <li> the already meshed <b> Source Face </b> and </li>
+ <li> the <b> Source Mesh </b> (It can be omitted only when
+ projecting a submesh on another one of the same Mesh). </li>
+ <li> It could also be necessary to define the orientation of mesh on
+ the face, which is done by indicating two <b>Source Vertices</b>,
+ which belong to the same edge of the <b>Source Face</b>, and
+ two <b>Target Vertices</b>, which belong to the same edge of the
+ face being meshed.</li>
+</ul>
+
+The groups of faces are suitable for this algorithm only if they
+contain an equal number of faces and form topologically equal
+structures.
+
+\section projection_1D2D Projection 1D-2D
+
+\n <b>Projection 1D-2D</b> algorithm differs from
+\ref projection_2D algorithm in one aspect: it generates mesh segments
+on edges of the face according to the projected 2D elements; thus it
+does not require the edges to be meshed by any other 1D algorithm;
+moreover it does not allow to mesh edges of the face using another
+algorithm via definition of sub-meshes.
+
+\section projection_3D Projection 3D
\n <b>Projection 3D</b> algorithm allows to define the mesh of a shape by
the projection of another already meshed shape. This algorithm works
