\page blsurf_hypo_page BLSURF Parameters hypothesis
+\anchor blsurf_top
\n BLSURF Parameters hypothesis works only with <b>BLSURF</b> 2d
algorithm. This algorithm is a commercial software.
-
+\n To get a licence, visit http://www.distene.com/corp/eval-distene.html
+
+<ol>
+<li>\ref blsurf_general_parameters "General parameters"</li>
+<li>\ref blsurf_advanced_parameters "Advanced parameters"</li>
+<li>\ref blsurf_local_size "Local size"</li>
+<ol>
+<li type="a">\ref blsurf_sizemap_computation "Computation of the physical size"</li>
+<li type="a">\ref blsurf_attractor "Advanced maps"</li>
+<li type="a">\ref blsurf_attractor_computation "Computation of attractors"</li>
+</ol>
+<li>\ref blsurf_enforced_elements "Enforced vertices"</li>
+<li>\ref blsurf_limitations "Limitations"</li>
+</ol>
+
+\anchor blsurf_general_parameters
<h1>General parameters</h1>
\image html blsurf_parameters.png
<li><b>Patch independent</b> - if checked, geometrical
edges are not respected and all geometrical faces are meshed as one
hyper-face.</li>
+</ul>
+\ref blsurf_top "Back to top"
+
+\anchor blsurf_advanced_parameters
<h1>Advanced parameters</h1>
+The notion of <i>diag</i> used in the descriptions means the diagonal of the bounding box of the
+geometrical object to mesh.
+
\image html blsurf_parameters_advanced.png
+<li><b>Verbosity level</b> - Defines the percentage of "verbosity" of
+BLSURF [0-100].</li>
+
<li><b>Topology</b> - allows creation of a conform mesh on a shell of
not sewed faces.
<ul>
<li>"Pre-process" and "Pre-process++" allow the BLSURF software to
pre-process the geometrical model to eventually produce a conform
mesh. </li>
+ <li>"PreCAD" is an auxiliary CAD pre-processing module which has
+ two main goals:
+ <ul>
+ <li> Complete missing or inadequate CAD descriptions.</li>
+ <li> Perform topology reconstruction and specific geometry
+ enhancement for mesh generation.</li>
+ </ul>
+ This module requires a specific licence.
+ \n
+ The following PreCAD options are the most significant and important ones:
+ <ul>
+ <li><b>Merge Edges</b> - allows PreCAD to optimize the geometry by merging some
+ edges. This option is 0 by default.</li>
+ <li><b>Remove nano edges</b> - allows PreCAD to optimize the geometry by removing
+ the nano edges whenever possible. This option is 0 by default.</li>
+ <li><b>Nano edge length</b> - gives the length below which an edge is considered as nano
+ for the topology processing. See also the \b remove_nano_edges option. If unset, PreCAD
+ default value is \f$\mathrm{diag} \times 10^{-5}\f$.</li>
+ <li><b>Discard input topology</b> - computes the CAD topology from scratch,
+ without considering the toplogical information contained in the original CAD
+ (Useful for iges files). This option is 0 by default.</li>
+ </ul>
+ </li>
</ul>
-<li><b>Verbosity level</b> - Defines the percentage of "verbosity" of
-BLSURF [0-100].</li>
+<li><b>ExportGMF</b> - saves the computed mesh into a GMF file (.mesh or .meshb).</li>
-<li><b>Add option</b> - provides the choice of multiple advanced
-options, which appear, if selected, in a table where it is possible to
-input the value of the option and to edit it later.</li>
+<li><b>Add option</b> - provides the choice of multiple PreCAD and BLSURF
+advanced options, which appear, if selected, in a table where it is
+possible to input the value of the option and to edit it later.</li>
-<li><b>Clear option</b> - removes the option selected in the table.
+<li><b>Clear option</b> - removes the option selected in the table.</li>
</ul>
\n
-The following options are commonly usable. The notion of <i>diag</i>
-used in the descriptions means
-the diagonal of the bounding box of the geometrical object to mesh.
+The following BLSURF options are commonly usable.
<ul>
-<li><b>topo_eps1</b> (real) - is the tolerance level inside a CAD
-patch. By default is equal to <i>diag</i> � 10-4. This tolerance is used to
+<li>\b topo_eps1 (real) - is the tolerance level inside a CAD
+patch. By default is equal to \f$\mathrm{diag} \times 10^{-4}\f$. This tolerance is used to
identify nodes to merge within one geometrical face when \b Topology
-option is to pre-process. Default is <i>diag</i>/10.0.</li>
+option is to pre-process.</li>
-<li><b>topo_eps2</b> (real) - is the tolerance level between two CAD
-patches. By default is equal to <i>diag</i> � 10-4. This tolerance is used to
+<li>\b topo_eps2 (real) - is the tolerance level between two CAD
+patches. By default is equal to \f$\mathrm{diag} \times 10^{-4}\f$. This tolerance is used to
identify nodes to merge over different geometrical faces when
-\b Topology option is to pre-process. Default is <i>diag</i>/10.0.</li>
+\b Topology option is to pre-process.</li>
<li>\b LSS (real) - is an abbreviation for "length of sub-segment". It is
-a maximal allowed length of a mesh edge. Default is 0.5.</li>
+a maximal allowed length of a mesh edge. Default is \f$0.5\f$.</li>
<li>\b frontal (integer)
<ul>
interpolated value <i>v</i> between two points <i>P1</i> and <i>P2</i> on a
curve. Let <i>h1</i> be the value at point <i>P1,</i> <i>h2</i> be the value at point
<i>P2,</i> and <i>t</i> be a parameter varying from 0 to 1 when moving from <i>P1
-to</i> <i>P2</i> .
+to</i> <i>P2</i>.
<ul>
-<li>0 - the interpolation is linear: <i>v = h1 + t (h2 - h1 )</i></li>
-<li>1 - the interpolation is geometric: <i>v = h1 * pow( h2/h1, t)</i></li>
-<li>2 - the interpolation is sinusoidal: <i>v = (h1+h2)/2 +
-(h1-h2)/2*cos(PI*t)</i></li>
+<li>0 - the interpolation is linear: \f$v = h1 + t (h2 - h1 )\f$</li>
+<li>1 - the interpolation is geometric: \f$v = h1 \times \left( \frac{h1}{h2} \right)^{t}\f$</li>
+<li>2 - the interpolation is sinusoidal: \f$v = \frac{h1+h2}{2} + \frac{h1-h2}{2 \cdot \cos(\pi \cdot t)}\f$</li>
</ul>
Default is 0.</li>
<li>\b hmean_flag (integer) - determines the computation of the average of several
values:<ul>
<li>-1 - the minimum is computed.</li>
-<li>0 or 2 - the arithmetic average computed.
+<li>0 or 2 - the arithmetic average is computed.
<li>1 - the geometric average is computed.</li>
</ul>
Default is 0.</li>
<li>\b eps_ends (real) - is used to detect the curves whose lengths are very
small, which sometimes constitutes an error. A message is printed
-if<i> fabs(P2-P1) < eps_ends</i>, where <i>P1</i> and <i>P2</i> are the
-extremities of a curve. Default is <i>diag</i>/500.0.</li>
+if \f$\left|P2-P1\right| < eps\_ends\f$, where <i>P1</i> and <i>P2</i> are the
+extremities of a curve. Default is \f$\frac{\mathrm{diag}}{500.0}\f$.</li>
<li>\b prefix (char) - is a prefix of the files generated by
BLSURF. Default is "x".</li>
files. Default is 1.</li>
</ul>
+\n
+The following PreCAD options are commonly usable.
+<ul>
+<li>\b closed_geometry (int) - describes whether the working geometry
+should be closed or not. When activated, this option helps PreCAD to process
+the dirtiest geometries. By default this option is 0.</li>
+<li>\b debug (int) - If debug = 1 PreCAD will be very verbose and will output
+some intermediate files in the working directory. By default this
+option is 0.</li>
+<li>\b eps_nano_relative (real) - the same as \b eps_nano, but relatively to
+the diagonal of the box bounding the geometry. By default this option is \f$10^{-5}\f$.</li>
+<li>\b eps_sewing (real) - tolerance of the assembly. It rarely requires to be tuned.
+By default this option is \f$\mathrm{diag} \times 5 \cdot 10^{-4}\f$.</li>
+<li>\b eps_sewing_relative (real) - the same as \b eps_nano but relatively to
+the diagonal of the box bounding the geometry. By default this option is \f$5 \cdot 10^{-4}\f$.</li>
+<li>\b manifold_geometry (int) - describes whether the working geometry should be manifold or not.
+When activated, this option helps PreCAD to process the dirtiest
+geometries. By default this option is 0.</li>
+<li>\b create_tag_collision (int) - creates new tags from original ones in case
+of collision (entity merge or association for example). By default
+this option is 0.</li>
+<li>\b periodic_tolerance (real) - defines the maximum distance error accepted between
+two sets of periodic entities. By default this option is \f$\mathrm{diag} \times 10^{-5}\f$.</li>
+<li>\b periodic_tolerance_relative (real) - the same as \b
+periodic_tolerance but in a relative unit. Bu default this option is \f$10^{-5}\f$.</li>
+<li>\b periodic_split_tolerance (real) - This periodicity processing related option defines
+the minimum distance between a CAD point and an imprinted point. It allows to indirectly
+control the number of created points and small edges. By default this
+option is \f$\mathrm{diag} \times 10^{-4}\f$.</li>
+<li>\b periodic_split_tolerance_relative (real - the same as \b
+periodic_split_tolerance but in a relative unit. By default this
+option is \f$10^{-4}\f$.</li>
+</ul>
+
\n
The following advanced options are not documented and you can use them
at your own risk.
<li> import_option </li>
</ul>
-<h1>Custom size map</h1>
+\ref blsurf_top "Back to top"
-\image html blsurf_parameters_sizemap1.png
+\anchor blsurf_local_size
+<h1>Local size</h1>
-User sizes can be defined on faces, edges or vertices.
+Local sizes can be defined on faces, edges or vertices.
<ul>
<li>The faces, edges and vertices can belong to the meshed geometrical
object or to its sub-shapes (created using <b>Explode</b> command).</li>
</ul></li>
</ul>
-\anchor blsurf_attractor
-<h2>Advanced maps</h2>
-\n
-\image html blsurf_parameters_sizemap2.png
-\n
-Specific size maps, called attractors can be defined on faces. They allow to define the size of the mesh elements on a face so that the mesh is the finest on the attractor shape and becomes coarser when getting far from this shape.
-The selected attractor can be either a Vertex or an Edge. The attractor doesn't have to be a sub-shape of the shape to mesh.
-\n
-Furthermore you can choose to keep the size constant until a certain distance from a shape. This option can be combined or not with the "attractor" size map described above.
-\n
-If the two options are combined the size will remain constant until the distant specified in "constant over" and grow then as prescribed by the attractor function. Else the growing is only controled by the standard arguments of BLSURF (gradation ...).
-
-\image html blsurf_attractors2.png "Example of mesh created using attractors, the attractors here are the side edges and the size grow from the side of the surface towards the apex"
-\n
-\image html blsurf_const_size_near_shape2.png "Example of size map with constant size option, the size is kept constant on the left side of the surface until a certain distance"
-\n
-Remark : The validation of the hypothesis might take a few seconds if attractors are defined or the "constant size" option is used because a map of distances has to be built on the whole surface for each face where such an hypothesis has been defined.
+3 different types of size maps can be defined:
+<ol>
+<li type="a">\ref blsurf_sizemap_computation "Computation of the physical size"</li>
+<li type="a">\ref blsurf_attractor "Advanced maps"</li>
+<li type="a">\ref blsurf_attractor_computation "Computation of attractors"</li>
+</ol>
-<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
+\ref blsurf_top "Back to top"
\anchor blsurf_sizemap_computation
<h2>Computation of the physical size</h2>
-\n
+\image html blsurf_parameters_sizemap1.png
+
The physical size is obtained by querying sizemap functions associated to the input CAD object for surfaces, curves and points.
Each function can either return a value h (which is then trimmed
between the two bounds hphymin and hphymax), or "no answer" (by not
</ul>
In order to compute the mean of several values, the arithmetic mean is used by default, but this can be modified by the parameter \ref blsurf_hmean_flag "hmean flag". In the same way, in order to interpolate two values, a linear interpolation is used by default, but this can be modified by \ref blsurf_hinterpol_flag "hinterpol flag".
+\ref blsurf_local_size "Back to \"Local size\"" \n
+\ref blsurf_top "Back to top"
+
+\anchor blsurf_attractor
+<h2>Advanced maps</h2>
+\n
+\image html blsurf_parameters_sizemap2.png
+\n
+More specific size maps can be defined on faces.
+
+<ul>
+<li> <i> Attractors </i> allow to define the size of the mesh elements
+on a face so that the mesh is the finest on the attractor shape and
+becomes coarser when getting far from this shape.
+<ul>
+<li> The selected attractor can be a Vertex, an Edge, a Wire or a
+Compound mixing several entities of those types.</li>
+<li> The attractor doesn't have to be a sub-shape of the shape to mesh.</li>
+<li> The size will grow exponentially (see the formula below) but is
+bounded by gradation, \n so if you want the formula to be strictly
+respected, you should set the <i>gradation</i>
+to its maximum (2.5) in the <i>arguments</i> tab.
+</ul>
+\n
+<li> Furthermore you can choose to <i> keep the size constant </i>
+until a certain distance from a shape. This option can be combined or
+not with an <i>attractor</i> size map described above.
+<ul>
+<li> If the two options are combined the size will remain constant
+until the distance specified in "constant over" and grow then as
+prescribed by the attractor function.</li>
+<li> Else the growing is only controled by the standard arguments of
+BLSURF (gradation ...).</li>
+</ul>
+</ul>
+
+\image html blsurf_const_size_near_shape2.png "Example of size map with constant size option, the size is kept constant on the left side of the surface until a certain distance"
+
+Remark : The validation of the hypothesis might take a few seconds if
+attractors are defined or the "constant size" option is used because a
+map of distances has to be built on the whole surface for each face
+where such a hypothesis has been defined.
+
+<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
+
+\ref blsurf_local_size "Back to \"Local size\"" \n
+\ref blsurf_top "Back to top"
+
\anchor blsurf_attractor_computation
<h2>Computation of attractors</h2>
\n
-The size grow exponentially following the equation : h(d) = User size + (h_start - User Size) * exp( -(d / R)^2 ).
+The size grows exponentially following the equation :
+\f$h(d) = \mathrm{User Size} + (\mathrm{h\_start} - \mathrm{User Size}) \times e ^ { - \left( \frac{d}{R} \right) ^ {2} }\f$
\n
Where :
<ul>
<li>h_start is the desired size on the given attractor shape</li>
-<li>d is the distance of the current point from the attractor shape. The distance is the geodesic distance (i.e. calculated by following the surface to be meshed) </li>
+<li>d is the distance of the current point from the attractor
+shape. The distance is the geodesic distance (i.e. calculated by following the surface to be meshed) </li>
<li>R is called the distance of influence and allows controlling the growth rate of the mesh </li>
</ul>
-Warning : The formula is respected only if it doesn't imply a gradation bigger than the one set in the "Arguments" tab. So it's better to set it to its maximum value : 2.5.
-<h1>Custom enforced vertices</h1>
+\image html blsurf_attractors2.png "Example of mesh created using attractors, the attractors here are the side edges and the size grows from the side of the surface towards the apex"
+
+\ref blsurf_local_size "Back to \"Local size\"" \n
+\ref blsurf_top "Back to top"
+
+\anchor blsurf_enforced_elements
+<h1>Enforced vertices</h1>
\image html blsurf_parameters_enforced_vertices.png
-It is possible to define some enforced vertices to BLSurf algorithm
-without creating any vertices by CAD algorithms.
+It is possible to define some enforced vertices to BLSurf algorithm.
+An enforced vertex is defined on a Face or a Compound by
+<ul>
+<li> selecting an existing Vertex or Compound,</li>
+<li> or creating a new vertex given its coordinates.</li>
+</ul>
+The enforced vertex is the projection of a point defined by its
+(x,y,z) coordinates on the selected face.
<ul>
-<li>The enforced vertex is the projection of a point defined by its
-(x,y,z) coordinates on the selected face.</li>
<li>It is possible to define several enforced vertices on a face or a group of faces.</li>
<li>If the projected point is on the boundary or outside of the face, it will be ignored.</li>
+<li>If a group name is specified, the enforced nodes will be added in the group. If the group does not exist it will be created.
</ul>
<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including enforced vertices.
+\ref blsurf_top "Back to top"
+
+\anchor blsurf_limitations
<h1>Limitations</h1>
Currently BLSURF plugin has the following limitations.
<ul>
- <li>The created mesh will contain inverted elements if it is based on a shape,
- consisting of more than one face (box, cone, torus...) and if
- the option "Allow Quadrangles (Test)" has been checked before
- computation.</li>
-
- <li>SIGFPE exception is raised at the attempt to compute the mesh
- based on a box when the option "Patch independent" is checked.</li>
-
<li>BLSURF algorithm cannot be used as a local algorithm (on
sub-meshes) or as a provider of a low-level
mesh for some 3D algorithms, because the BLSURF mesher (and
<li> BLSURF + Projection 2D from faces meshed by BLSURF;</li>
<li> local BLSURF + Extrusion 3D;</li>
</ul>
- </li>
+ </li>
</ul>
+\ref blsurf_top "Back to top"
+
*/
