3 \page blsurf_hypo_page BLSURF Parameters hypothesis
5 \n BLSURF Parameters hypothesis works only with <b>BLSURF</b> 2d
6 algorithm. This algorithm is a commercial software.
8 \image html blsurf_parameters.png
11 <li><b>Name</b> - allows to define the name of the hypothesis (BLSURF
12 Parameters by default).</li>
14 <li><b>Physical Mesh</b> - if is set to "Custom", allows to set size
15 of mesh elements to generate in <b>User size</b> field.
18 <li><b>User size</b> - size of mesh elements to generate. </li>
20 <li><b>Max Physical Size</b> - is an upper limit of mesh element size. </li>
22 <li><b>Min Physical Size</b> - is a lower limit of mesh element size. </li>
24 <li><b>Geometrical mesh</b> - if is set to "Custom", allows to set
25 mesh element deflection from curves and surfaces and element
26 size change rate in <b>Angle Mesh S</b>, <b>Angle Mesh C</b> and
27 <b>Gradation</b> fields correspondingly. These fields control
28 computation of element size, so called <i>geometrical size</i>, conform to
29 the surface geometry considering local curvatures. \n
30 The eventual element size at each point will be minimum of <b>User
31 size</b>, if given, and the <i>geometrical size</i>. </li>
33 <li><b>Angle Mesh S</b> - maximal allowed angle in degrees at a mesh
34 node between the mesh face and the tangent to the geometrical surface. </li>
36 <li><b>Angle Mesh C</b> - maximal allowed angle in degrees at a mesh
37 node between the mesh edge and the tangent to the geometrical curve. </li>
39 <li><b>Max Geometrical Size</b> - is an upper limit of <i>geometrical size</i>.</li>
41 <li><b>Min Geometrical Size</b> - is a lower limit of <i>geometrical size</i>.</li>
43 <li><b>Gradation</b> - maximal allowed ratio between the lengths of
44 two adjacent edges. </li>
46 <li><b>Allow Quadrangles</b> - to create quadrilateral elements.</li>
48 <li><b>Patch independent</b> - if this box is checked on, geometrical
49 edges are not respected and all geometrical faces are meshed as one
52 \image html blsurf_parameters_advanced.png
54 <li><b>Topology</b> - allows creation of a conform mesh on a shell of
57 <li>"From CAD" means that mesh conformity is assured by conformity
59 <li>"Pre-process" and "Pre-process++" let BLSURF software
60 pre-process the geometrical model to eventually produce a conform
64 <li><b>Verbosity level</b> - Defines the percentage of "verbosity" of
67 <li><b>Add option</b> - provides a choice of multiple advanced
68 options, each of which, if selected, appear in a table where you can
69 enter a value of the option and edit it later.</li>
71 <li><b>Clear option</b> - removes option selected in the table.
76 Commonly usable options are following. The name <i>diag</i> stands there for
77 the diagonal of the bounding box of the geometrical object to mesh.
80 <li><b>topo_eps1</b> (real) - is the tolerance level inside a CAD
81 patch. By default is equal to <i>diag</i> × 10-4. This tolerance is used to
82 identify nodes to merge within one geometrical face when \b Topology
83 option is to pre-process. Default is <i>diag</i>/10.0.</li>
85 <li><b>topo_eps2</b> (real) - is the tolerance level between two CAD
86 patches. By default is equal to <i>diag</i> × 10-4. This tolerance is used to
87 identify nodes to merge over different geometrical faces when
88 \b Topology option is to pre-process. Default is <i>diag</i>/10.0.</li>
90 <li>\b LSS (real) - is an abbreviation for "length of sub-segment". It is
91 a maximal allowed length of a mesh edge. Default is 0.5.</li>
93 <li>\b frontal (integer)
95 <li> 1 - the mesh generator inserts points with an advancing front method.</li>
96 <li> 0 - it inserts them with an algebraic method (on internal edges). This method is
97 slightly faster but generates less regular meshes. </li>
101 <li>\b hinterpol_flag (integer) - determines the computation of an
102 interpolated value <i>v</i> between two points <i>P1</i> and <i>P2</i> on a
103 curve. Let <i>h1</i> be the value at point <i>P1,</i> <i>h2</i> be the value at point
104 <i>P2,</i> and <i>t</i> be a parameter varying from 0 to 1 when moving from <i>P1
107 <li>0 - the interpolation is linear: <i>v = h1 + t (h2 - h1 )</i></li>
108 <li>1 - the interpolation is geometric: <i>v = h1 * pow( h2/h1, t)</i></li>
109 <li>2 - the interpolation is sinusoidal: <i>v = (h1+h2)/2 +
110 (h1-h2)/2*cos(PI*t)</i></li>
114 <li>\b hmean_flag (integer) - determines the computation of the mean of several
116 <li>-1 - the minimum is computed.</li>
117 <li>0 or 2 - the arithmetic mean computed.
118 <li>1 - the geometric mean is computed.</li>
122 <li>\b CheckAdjacentEdges, \b CheckCloseEdges and \b CheckWellDefined
123 (integers) - give number of calls of equally named subroutines the
124 purpose of which is to improve the mesh of domains having narrow
125 parts. At each iteration,\b CheckCloseEdges decreases the sizes of the
126 edges when two boundary curves are neighboring,\b CheckAdjacentEdges
127 balances the sizes of adjacent edges, and \b CheckWellDefined checks if
128 the parametric domain is well defined. Default values are 0.</li>
131 <li>\b CoefRectangle (real)- defines the relative thickness of the rectangles
132 used by subroutine \b CheckCloseEdges (see above). Default is 0.25.</li>
134 <li>\b eps_collapse (real) - if is more than 0.0, BLSURF removes
135 curves whose lengths are less than \b eps_collapse. Here, to obtain an
136 approximate value of the length of a curve, the latter is arbitrarily
137 split into 20 edges. Default is 0.0.</li>
139 <li>\b eps_ends (real) - is used to detect curves whose lengths are very
140 small, which sometimes constitutes an error. A message is printed
141 if<i> fabs(P2-P1) < eps_ends</i>, where <i>P1</i> and <i>P2</i> are the
142 extremities of a curve. Default is <i>diag</i>/500.0.</li>
144 <li>\b prefix (char) - is a prefix of the files generated by
145 BLSURF. Default is "x".</li>
147 <li>\b refs (integer) - reference of a surface, used when exporting
148 files. Default is 1.</li>
152 The following advanced options are not documented and you can use them
154 \n\n Interger variables:
156 <li> addsurf_ivertex</li>
157 <li> background </li>
159 <li> communication </li>
161 <li> export_flag </li>
165 <li> intermedfile </li>
169 <li> pardom_flag </li>
172 <li> surforient </li>
174 <li> topo_collapse </li>
178 <li> addsurf_angle </li>
181 <li> addsurf_FG </li>
183 <li> addsurf_PA </li>
184 <li> angle_compcurv </li>
185 <li> angle_ridge </li>
186 <li> eps_pardom </li>
190 <li> export_format </li>
191 <li> export_option </li>
192 <li> import_option </li>
197 Currently BLSURF plugin has the following limitations.
199 <li>Mesh contains inverted elements, if it is based on shape,
200 consisting of more than one face (box, cone, torus...) and if
201 the option "Allow Quadrangles (Test)" was checked before
204 <li>SIGFPE exception is raised at trying to compute mesh, based on
205 box, with checked option "Patch independent".</li>
207 <li>It has been found out that BLSURF algorithm can't be used as a
208 local algorithm (on sub-meshes) and as a provider of low-level
209 mesh for some 3D algorithms because BLSURF mesher (and
210 consequently plugin) does not provide information on node
211 parameters on edges (U) and faces (U,V). For example the
212 following combinations of algorithms are impossible:
214 <li> global MEFISTO or Quadrangle(mapping) + local BLSURF;</li>
215 <li> BLSUFR + Projection 2D from faces meshed by BLSURF;</li>
216 <li> local BLSURF + Extrusion 3D;</li>