\page blsurf_hypo_page BLSURF Parameters hypothesis
\anchor blsurf_top
-BLSURF Parameters hypothesis works only with \b DISTENE \b BLSurf 2d
-algorithm. This algorithm is a commercial software. To obtain a
-licence, visit http://www.distene.com/en/corp/eval-distene.html
-\tableofcontents
+\tableofcontents
\section blsurf_general_parameters General parameters
- <b>Name</b> - allows defining the name of the hypothesis (BLSURF
Parameters_n by default).
-- <b>Physical Mesh</b> - can be set to <em>None</em>, <em>Custom</em>
- or <em>Size Map</em>
+- <b>Physical Mesh</b> - can be set to <em>None</em>, <em>Global size</em>
+ or <em>Local size</em>
- - if set to <em>Custom</em>, allows user input in the in <b>User size</b>,
- <b>Max Physical Size</b> and <b>Min Physical Size</b> fields.
+ - if set to <em>Global size</em>, only the <b>User size</b>,
+ <b>Max Size</b> and <b>Min Size</b> fields are taken into account.
- - if set to <em>Size Map</em>, behaves like <em>Custom</em> mode and takes into
- account the custom elements sizes given in the Size Map tab.
+ - if set to <em>Local size</em>, behaves like <em>Custom</em> mode and takes into
+ account the "Gradation" parameter and the custom elements sizes given in the
+ "Local size" tab.
-- <b>User size</b> - defines the size of the generated mesh elements.
+- <b>Geometrical mesh</b> - can be set to <em>None</em>, <em>Global size</em>
-- <b>Max Physical Size</b> - defines the upper limit of mesh element size.
+ - if set to <em>Global size</em>, allows user input in <b>Mesh angle</b>,
+ <b>Mesh distance</b> and <b>Gradation</b> fields. These fields control
+ computation of the element size, so called <i>geometrical size</i>, conform
+ to the surface geometry considering local curvatures. If both the <b>User size</b>
+ and the <i>geometrical parameters</i> are defined, the eventual element size
+ corresponds to the least of the two.
-- <b>Min Physical Size</b> - defines the lower limit of mesh element size.
+- <b>User size</b> - defines the size of the generated mesh elements. If "Relative value"
+is checked, the value is relative to the diagonal of the shape.
-- <b>Geometrical mesh</b> - if set to <em>Custom</em>, allows user input in
-<b>Angle Mesh S</b>, <b>Angle Mesh C</b> and <b>Gradation</b>
-fields. These fields control computation of the element size, so
-called <i>geometrical size</i>, conform to the surface geometry
-considering local curvatures. If both the <b>User size</b> and the
-<i>geometrical size</i> are defined, the eventual element size
-corresponds to the least of the two.
+- <b>Max Size</b> - defines the upper limit of mesh element size. If "Relative value"
+is checked, the value is relative to the diagonal of the shape.
-- <b>Angle Mesh S</b> - maximum angle between the mesh face and the
-tangent to the geometrical surface at each mesh node, in degrees.
+- <b>Min Size</b> - defines the lower limit of mesh element size. If "Relative value"
+is checked, the value is relative to the diagonal of the shape.
-- <b>Angle Mesh C</b> - maximum angle between the mesh edge and the
-tangent to the geometrical curve at each mesh node, in degrees.
+- <b>Gradation</b> - maximum ratio between the lengths of two adjacent edges.
-- <b>Max Geometrical Size</b> - defines the upper limit of the
- <i>geometrical size</i>.
+- <b>Quadratic mesh</b> - if checked, quadratic elements will be generated.
-- <b>Min Geometrical Size</b> - defines the lower limit of the
- <i>geometrical size</i>.
+- <b>Mesh angle</b> - Limiting angle (in degree) between the plane of a triangle of the mesh and each of the tangent planes at the three vertices.
+The smaller this angle is, the closer the mesh is to the exact surface, and the denser the resulting mesh is.
-- <b>Gradation</b> - maximum ratio between the lengths of two adjacent
- edges.
+- <b>Mesh distance</b> - Maximum desired distance between a triangle and its supporting CAD surface.
+The smaller this distance is, the closer the mesh is to the exact surface (only available in isotropic meshing).
-- <b>Allow Quadrangles</b> - if checked, allows the creation of
- quadrilateral elements.
+- <b>Anisotropic</b> - if checked, this parameter defines the maximum anisotropic ratio of the metric governing the anisotropic meshing process.
+The default value (0) means that the metric (and thus the generated elements) can be arbitrarily stretched.
-- <b>Patch independent</b> - if checked, geometrical edges are not
-respected and all geometrical faces are meshed as one hyper-face.
+- <b>Remove tiny edges</b> - if checked, the tiny (nano) edges are removed from the generated mesh.
+The tiny edge value defines the minimal length under which an edge is considered to be a tiny one.
-\ref blsurf_top "Back to top"
+- <b>Remove bad elements</b> - if checked, the bad elements (slivers) are removed from the generated mesh.
+The bad element value defines the aspect ratio triggering the "bad element” classification.
-\section blsurf_advanced_parameters Advanced parameters
+- <b>Mesh optimisation</b> - if checked, the mesh will be optimized in order to get better shaped elements.
-The notion of <i>diag</i> used in the descriptions means the diagonal
-of the bounding box of the geometrical object to mesh.
+- <b>Allow Quadrangles</b> - if checked, allows the creation of quadrilateral elements.
-\image html blsurf_parameters_advanced.png
-
-- <b>Verbosity level</b> - defines the percentage of "verbosity" of
-BLSURF [0-100].
+\ref blsurf_top "Back to top"
-- <b>Topology</b> - allows creation of a conform mesh on a shell of
-not sewed faces. The following choices are allowed:
+\section blsurf_advanced_parameters Advanced parameters
- - <em>"From CAD"</em> means that mesh conformity is assured by conformity
- of a shape.
+The notion of <i>diag</i> used in the descriptions means the diagonal of the bounding box of the geometrical object to mesh.
- - <em>"Pre-process"</em> and <em>"Pre-process++"</em> allow the BLSURF software to
- pre-process the geometrical model to eventually produce a conform
- mesh.
+\image html blsurf_parameters_advanced.png
- - <em>"PreCAD"</em> is an auxiliary CAD pre-processing module which has
- two main goals:
+- <b>PreCAD options</b> -if checked, the PreCAD module will be used. This module has
+two main goals:
- - Complete missing or inadequate CAD descriptions.
+ - Complete missing or inadequate CAD descriptions.
- - Perform topology reconstruction and specific geometry
- enhancement for mesh generation.
+ - Perform topology reconstruction and specific geometry
+ enhancement for mesh generation.
- \n This module requires a specific licence. The following PreCAD
- options are the most significant and important ones:
+ \n This module requires a specific licence. The following PreCAD
+ options are the most significant and important ones:
- <b>Merge Edges</b> - allows PreCAD to optimize the geometry by merging some
- edges. This option is 0 by default.
+ edges. This option is checked by default.
- - <b>Remove nano edges</b> - allows PreCAD to optimize the geometry by removing
- the nano edges whenever possible. This option is 0 by default.
-
- - <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$\mathrm{diag} \times 10^{-5}\f$.
+ - <b>Process 3D topology</b> - allows PreCAD to perform the cleanup processing.
+ This option is checked by default.
- <b>Discard input topology</b> - computes the CAD topology from scratch,
without considering the topological information contained in the original CAD
- (useful for iges files). This option is 0 by default.
+ (useful for iges files). This option is unchecked by default.
+
+- <b>Verbosity level</b> - defines the percentage of "verbosity" of
+MeshGems-CADSurf and MeshGems-PreCAD [0-100].
- <b>ExportGMF</b> - saves the computed mesh into a GMF file (.mesh or .meshb).
The following BLSURF options are commonly usable:
-- \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.
-
-- \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.
-
-- \b LSS (real) - is an abbreviation for "length of sub-segment". It is
-a maximal allowed length of a mesh edge. Default is \f$0.5\f$.
-
- \b frontal (integer)
- 1 - the mesh generator inserts points with an advancing front method.
- - 0 - it inserts them with an algebraic method (on internal edges). This method is
+ - 0 - it inserts them with an algebraic method (on internal edges). This method is
slightly faster but generates less regular meshes.
- \n Default is 0.
+ \n Default is 1.
- \anchor blsurf_hinterpol_flag \b hinterpol_flag (integer) - determines the computation of an
interpolated value <i>v</i> between two points <i>P1</i> and <i>P2</i> on a
\n Default is 0.
-- \b CheckAdjacentEdges, \b CheckCloseEdges and \b CheckWellDefined
-(integers) - give the number of calls of equally named subroutines the
-purpose of which is to improve the mesh of domains having narrow
-parts. At each iteration,\b CheckCloseEdges decreases the sizes of the
-edges when two boundary curves are neighboring,\b CheckAdjacentEdges
-balances the sizes of adjacent edges, and \b CheckWellDefined checks if
-the parametric domain is well defined. Default values are 0.
+The following PreCAD options are commonly usable.
+
+- \b closed_geometry (boolean) - 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.
+
+- \b create_tag_collision (boolean) - creates new tags from original ones in case
+of collision (entity merge or association for example). By default
+this option is 1.
-- \b CoefRectangle (real)- defines the relative thickness of the rectangles
-used by subroutine \b CheckCloseEdges (see above). Default is 0.25.
+- \b debug (bool) - If debug = 1 PreCAD will be very verbose and will output
+some intermediate files in the working directory. By default this
+option is 0.
-- \b eps_collapse (real) - if more than 0.0, BLSURF removes
-curves whose lengths are less than \b eps_collapse. To obtain an
-approximate value of the length of a curve, it is arbitrarily
-split into 20 edges. Default is 0.0.
+- \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.
-- \b eps_ends (real) - is used to detect the curves whose lengths are very
-small, that sometimes constitutes an error. A message is printed
-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$\frac{\mathrm{diag}}{500.0}\f$.
+- \b periodic_tolerance (real) - defines the maximum distance error accepted between
+two sets of periodic entities. By default this option is \f$\mathrm{diag} \times 10^{-5}\f$.
-- \b prefix (char) - is a prefix of the files generated by
-BLSURF. Default is "x".
+- \b remove_tiny_edges (boolean) -optimize the geometry by removing the nano edges whenever possible.
+By default this option is 0.
-- \b refs (integer) - reference of a surface, used when exporting
-files. Default is 1.
+- \b required_entities (char) -controls the correction operations. Possible values are:
-The following PreCAD options are commonly usable.
+ - "respect" - PreCAD is not allowed to correct or optimize a required edge.
-- \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.
+ - "ignore" - PreCAD is allowed to correct a required edge.
-- \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.
+ - "clear" - PreCAD will erase "required" status of each required entities, and will thus
+ be allowed to correct a required edge.
-- \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$10^{-5}\f$.
+ \n By default this option is "respect".
-- \b eps_sewing (real) - tolerance of the assembly. It rarely requires to be tuned.
+- \b sewing_tolerance (real) - tolerance of the assembly. It rarely requires to be tuned.
By default this option is \f$\mathrm{diag} \times 5 \cdot 10^{-4}\f$.
-- \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$5 \cdot 10^{-4}\f$.
+- \b tags (char) -controls the optimisation process. Possible values are:
-- \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.
+ - "respect" - PreCAD is not allowed to cross the CAD attributes boundaries for optimisation purpose.
-- \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.
+ - "ignore" - PreCAD is allowed to cross the CAD attributes boundaries for optimisation.
-- \b periodic_tolerance (real) - defines the maximum distance error accepted between
-two sets of periodic entities. By default this option is \f$\mathrm{diag} \times 10^{-5}\f$.
+ - "clear" - PreCAD will erase each tgas of each entities, and will thus
+ be allowed to cross the CAD attributes boundaries in its optimisation purpose.
-- \b periodic_tolerance_relative (real) - the same as \b periodic_tolerance but in a relative unit.
-By default this option is \f$10^{-5}\f$.
+ \n By default this option is "respect".
-- \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$\mathrm{diag} \times 10^{-4}\f$.
-
-- \b periodic_split_tolerance_relative (real - the same as \b
-periodic_split_tolerance but in a relative unit. By default this
-option is \f$10^{-4}\f$.
-
-The following advanced options are not documented and you can use them
-at your own risk.
-
-- Integer variables:
- - addsurf_ivertex
- - anisotropic
- - background
- - coiter
- - communication
- - decim
- - export_flag
- - file_h
- - gridnu
- - gridnv
- - intermedfile
- - memory
- - normals
- - optim
- - pardom_flag
- - pinch
- - rigid
- - surforient
- - tconf
- - topo_collapse
-- Real variables:
- - addsurf_angle
- - addsurf_R
- - addsurf_H
- - addsurf_FG
- - addsurf_r
- - addsurf_PA
- - angle_compcurv
- - angle_ridge
- - anisotropic_ratio
- - eps_pardom
-- String variables:
- - export_format
- - export_option
- - import_option
+- \b tiny_edge_length (real) - the length below which en edge is considered as nano for the topology processing.
+By default this option is \f$10^{-5}\f$.
\ref blsurf_top "Back to top"
- If a group name is specified : If the group exists, the enforced nodes will be added in the existing group, if the group does not exist it will be created.
+All the internal vertices of the faces can be considered as enforced vertices if the corresponding checkbox is checked.
+A group can optionnaly be defined on those enforced vertices.
+
\sa Sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including enforced vertices.
\ref blsurf_top "Back to top"
