\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
<h1>General parameters</h1>
<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-description.</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. Default is 0.</li>
+ <li><b>Remove nano edges</b> - allows PreCAD to optimize the geometry by removing
+ the nano edges whenever possible. Default is 0.</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). Default is 0.</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 treat
+the most dirtiest geometries. Default 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. Default is 0.</li>
+<li>\b eps_nano_relative (real) - Same as \b eps_nano but given in relatively to
+the diagonal of the box bounding the geometry. Default is \f$10^{-5}\f$.</li>
+<li>\b eps_sewing (real) - tolerance of the assembly. It rarely requires to be tuned.
+Default is \f$\mathrm{diag} \times 5 \cdot 10^{-4}\f$.</li>
+<li>\b eps_sewing_relative (real) - Same as \b eps_nano but given in relatively to
+the diagonal of the box bounding the geometry. Default 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 treat the most dirtiest geometries. Default is 0.</li>
+<li>\b create_tag_collision (int) - creates some new tags from original ones in case
+of collision (entity merge or association for example). Default is 0.</li>
+<li>\b periodic_tolerance (real) - defines the maximum distance error accepted between
+two sets of periodic entities. Default is \f$\mathrm{diag} \times 10^{-5}\f$.</li>
+<li>\b periodic_tolerance_relative (real) - Same as \b periodic_tolerance but in relative
+unit. Default 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 points and small edges created. Default is \f$\mathrm{diag} \times 10^{-4}\f$.</li>
+<li>\b periodic_split_tolerance_relative (real - Same as \b periodic_split_tolerance but in
+relative unit. Default is \f$10^{-4}\f$.</li>
+</ul>
+
\n
The following advanced options are not documented and you can use them
at your own risk.
<h1>Custom size map</h1>
-\image html blsurf_parameters_sizemap.png
+\image html blsurf_parameters_sizemap1.png
User sizes can be defined on faces, edges or vertices.
<ul>
</ul></li>
</ul>
-<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
-
\anchor blsurf_sizemap_computation
<h2>Computation of the physical size</h2>
\n
</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".
+\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_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"
+\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 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.
+
+\anchor blsurf_attractor_computation
+<h2>Computation of attractors</h2>
+\n
+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>R is called the distance of influence and allows controlling the growth rate of the mesh </li>
+</ul>
<h1>Custom enforced vertices</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
following combinations of algorithms are impossible:
<ul>
<li> global MEFISTO or Quadrangle(mapping) + local BLSURF;</li>
- <li> BLSUFR + Projection 2D from faces meshed by BLSURF;</li>
+ <li> BLSURF + Projection 2D from faces meshed by BLSURF;</li>
<li> local BLSURF + Extrusion 3D;</li>
</ul>
- </li>
+ </li>
</ul>
*/
