0022364, 0022363: EDF SMESH: Create Mesh dialog box improvement

[modules/smesh.git] / doc / salome / gui / SMESH / input / 2d_meshing_hypo.doc

diff --git a/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc b/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
index d72e4d50459e39613ca3ac0bca641acd810f497a..e019c8b87ff3c96bc64f282dc329f8b3395aab1b 100644 (file)
--- a/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
+++ b/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
@@ -2,22 +2,17 @@
 
 \page a2d_meshing_hypo_page 2D Meshing Hypotheses
 
 
 \page a2d_meshing_hypo_page 2D Meshing Hypotheses
 

-<br>
-<ul>
-<li>\ref max_element_area_anchor "Max Element Area"</li>
-<li>\ref length_from_edges_anchor "Length from Edges"</li>
-<li>\ref hypo_quad_params_anchor "Quadrangle parameters"</li>
-</ul>
+- \ref max_element_area_anchor "Max Element Area"
+- \ref length_from_edges_anchor "Length from Edges"
+- \ref hypo_quad_params_anchor "Quadrangle parameters"

 
 

-<br>

 \anchor max_element_area_anchor
 <h2>Max Element Area</h2>
 
 \anchor max_element_area_anchor
 <h2>Max Element Area</h2>
 

-<b>Max Element Area</b> hypothesis is applied for meshing of 2D faces
+<b>Max Element Area</b> hypothesis is applied for meshing of faces

 composing your geometrical object. Definition of this hypothesis
 composing your geometrical object. Definition of this hypothesis

-consists of setting the <b>maximum area</b> of meshing elements (depending on
-the chosen meshing algorithm it can be <b>triangles</b> or <b>quadrangles</b>),
-which will compose the mesh of these 2D faces.
+consists of setting the <b>maximum area</b> of mesh elements,
+which will compose the mesh of these faces.

 
 \image html a-maxelarea.png
 
 
 \image html a-maxelarea.png
 


@@ -26,32 +21,67 @@ which will compose the mesh of these 2D faces.
 \image html max_el_area.png "In this example, Max. element area is very small compared to the 1D hypothesis"
 
 <b>See Also</b> a sample TUI Script of a 
 \image html max_el_area.png "In this example, Max. element area is very small compared to the 1D hypothesis"
 
 <b>See Also</b> a sample TUI Script of a 

-\ref tui_max_element_area "Maximum Element Area" hypothesis
-operation. 
+\ref tui_max_element_area "Maximum Element Area" hypothesis operation. 

 
 

-<br>

 \anchor length_from_edges_anchor
 <h2>Length from Edges</h2>
 
 \anchor length_from_edges_anchor
 <h2>Length from Edges</h2>
 

-<b>Length from edges</b> hypothesis builds 2D mesh segments having a
-length calculated as an average edge length for a given wire.
+<b>Length from edges</b> hypothesis builds 2D mesh elements having a
+maximum linear size calculated as an average segment length for a wire
+of a given face.

 
 <b>See Also</b> a sample TUI Script of a 
 \ref tui_length_from_edges "Length from Edges" hypothesis operation.
 
 
 <b>See Also</b> a sample TUI Script of a 
 \ref tui_length_from_edges "Length from Edges" hypothesis operation.
 

-<br>

 \anchor hypo_quad_params_anchor
 <h2>Quadrangle parameters</h2>
 
 \image html hypo_quad_params_dialog.png "Quadrangle parameters creation/edition dialog"
 
 \anchor hypo_quad_params_anchor
 <h2>Quadrangle parameters</h2>
 
 \image html hypo_quad_params_dialog.png "Quadrangle parameters creation/edition dialog"
 

-<b>Quadrangle parameters</b> is a hypothesis for Quadrangle (Mapping).
-
-<b>Base vertex</b> parameter allows using Quadrangle (Mapping)
-algorithm for meshing of triangular faces. In this case it is
+<b>Quadrangle parameters</b> is a hypothesis for Quadrangle (Mapping) algorithm.
+
+<b>Transition</b> tab is used to define the algorithm of transition
+between opposite sides of faces with a different number of
+segments on opposite sides. The following types of transition
+algorithms are available:
+
+- <b>Standard</b> is the default case, when both triangles and quadrangles
+  are possible in the transition area along the finer meshed sides.
+- <b>Triangle preference</b> forces building only triangles in the
+  transition area along the finer meshed sides.
+  \note This type corresponds to <b>Triangle Preference</b> additional hypothesis,
+  which is obsolete now.
+- <b>Quadrangle preference</b> forces building only quadrangles in the
+  transition area along the finer meshed sides. This hypothesis has a
+  restriction: the total quantity of segments on all
+  four sides of the face must be even (divisible by 2).
+  \note This type corresponds to <b>Quadrangle Preference</b> additional hypothesis,
+  which is obsolete now.
+- <b>Quadrangle preference (reversed)</b> works in the same way and
+  with the same restriction as <b>Quadrangle preference</b>, but
+  the transition area is located along the coarser meshed sides.
+- <b>Reduced</b> type forces building only quadrangles and the transition
+  between the sides is made gradually, layer by layer. This type has
+  a limitation on the number of segments: one pair of opposite sides must have
+  the same number of segments, the other pair must have an even difference
+  between the numbers of segments on the sides. In addition, the number
+  of rows between sides with different discretization
+  should be enough for the transition. Following the fastest transition
+  pattern, three segments become one (see the image below), hence
+  the least number of face rows needed to reduce from Nmax segments
+  to Nmin segments is log<sub>3</sub>( Nmax / Nmin ). The number of
+  face rows is equal to the number of segments on each of equally
+  discretized sides.
+
+\image html reduce_three_to_one.png "The fastest transition pattern: 3 to 1"
+
+<b>Base vertex</b> tab allows using Quadrangle (Mapping)
+algorithm for meshing of trilateral faces. In this case it is

 necessary to select the vertex, which will be used as the fourth edge
 (degenerated).
 
 necessary to select the vertex, which will be used as the fourth edge
 (degenerated).
 

+\image html hypo_quad_params_dialog_vert.png "Base Vertex tab of Quadrangle parameters creation/edition dialog"
+

 \image html hypo_quad_params_1.png "A face built from 3 edges"
 
 \image html hypo_quad_params_res.png "The resulting mesh"
 \image html hypo_quad_params_1.png "A face built from 3 edges"
 
 \image html hypo_quad_params_res.png "The resulting mesh"


@@ -68,32 +98,39 @@ shows the good (left) and the bad (right) results of meshing.
 
 \image html hypo_quad_params_res_2.png "The resulting meshes"
 
 
 \image html hypo_quad_params_res_2.png "The resulting meshes"
 

-<b>Type</b> parameter is used on faces with a different number of
-segments on opposite sides to define the algorithm of transition
-between them. The following types are available:
+\image html hypo_quad_params_dialog_enf.png "Enforced nodes tab of Quadrangle parameters creation/edition dialog"

 
 

+<b>Enforced nodes</b> tab allows for defining points where the
+algorithm should create nodes. There are two ways to define positions
+of the enforced nodes.

 <ul>
 <ul>

-<li><b>Standard</b> is the default case, when both triangles and quadrangles
-    are possible in the transition area along the finer meshed sides.</li>
-<li><b>Triangle preference</b> forces building only triangles in the
-    transition area along the finer meshed sides.
-    <i>This type corresponds to <b>Triangle Preference</b> additional
-    hypothesis, which is obsolete now.</i></li>
-<li><b>Quadrangle preference</b> forces building only quadrangles in the
-    transition area along the finer meshed sides. This hypothesis has a
-    restriction: the total quantity of segments on all
-    four sides of the face must be even (divisible by 2).</li>
-    <i>This type corresponds to <b>Quadrangle Preference</b>
-    additional hypothesis, which is obsolete now.</i></li>
-<li><b>Quadrangle preference (reversed)</b> works in the same way and
-with the same restriction as <b>Quadrangle preference</b>, but
-    the transition area is located along the coarser meshed sides.</li>
-<li><b>Reduced</b> type forces building only quadrangles and the transition
-    between the sides is made gradually, layer by layer. This type has
-    a limitation on the number of segments: one pair of opposite sides must have
-    the same number of segments, the other pair must have an even difference
-    between the numbers of segments on the sides.</li>
+  <li>\b Vertices group allows to set up shapes whose vertices will
+    define positions of the enforced nodes. Only vertices successfully
+    projected to the meshed face and located close enough to the
+    meshed face will be used to create the enforced nodes.</li>
+  <li> \b Points group allows to explicitly define coordinates of
+    points used to create the enforced nodes. Only points successfully
+    projected to the meshed face and located close enough to the
+    meshed face will be used to create the enforced nodes.</li>

 </ul>
 </ul>

+Algorithm of creation of the enforced nodes is following.
+
+\image html hypo_quad_params_enfnodes_algo.png "Steps of the algorithm of creation of the enforced nodes"
+<ol>
+  <li> Left image: Positions of nodes are computed without taking into
+  account the enforced vertex (yellow point).</li> 
+  <li> Middle image: A node closest to the enforced vertex is
+    detected. Extreme nodes of the row and column of the detected node
+    are used to create virtual edges (yellow lines) ending at the
+    enforced vertex. </li>
+  <li> Right image: The meshed face is thus divided by the virtual
+    edges into four quadrilateral sub-domains each of which is meshed
+    as usually: the nodes of the row and column of detected node are
+    moved to the virtual edges and the quadrilateral elements are
+    constructed. 
+</ol>
+If there are several enforced vertices, the algorithm is applied
+recursively to the formed sub-domains.

 
 <b>See Also</b> a sample TUI Script of a 
 \ref tui_quadrangle_parameters "Quadrangle Parameters" hypothesis.
 
 <b>See Also</b> a sample TUI Script of a 
 \ref tui_quadrangle_parameters "Quadrangle Parameters" hypothesis.