3 \page ghs3d_hypo_page MG-Tetra Parameters hypothesis
6 MG-Tetra Parameters hypothesis works only with <b>MG-Tetra</b>
7 algorithm. This algorithm is a commercial software.
9 To get a license, visit http://www.meshgems.com/meshgems-products.html
13 \section ghs3d_general_parameters General parameters
15 \image html ghs3d_parameters_basic.png
17 - <b>Name</b> - allows to define the name of the hypothesis (MG-Tetra
18 Parameters by default).
20 - <b>Optimization level</b> - allows choosing the required
21 optimization level (higher level of optimization provides better mesh,
22 but can be time-consuming):
34 - <b>Minimal size</b> - sets the minimum edge size in the generated mesh.
36 - <b>Maximal size</b> - sets the maximum edge size in the generated mesh.
38 - <b>Volumic gradation</b> - Defines the volumic ratio between 2 consecutive elements.
39 WARNING: Changing the default value of this parameter may dramatically
40 decrease the quality of the resulting mesh.
42 - <b>Use volume proximity</b> - activates consideration of distance between opposite surfaces.
44 - <b>Number of layers</b> - asks for at least given number of layers of tets between opposite surfaces.
46 - <b>Mesh holes</b> - if checked, the algorithm will
47 create mesh in the holes inside a solid shape, else only the outermost
48 shape will be meshed. Volumic elements created within holes are bound
51 - <b>Make groups of domains</b> - if checked, the algorithm will
52 create groups of just generated elements corresponding to each mesh
55 \ref ghs3d_top "Back to top"
57 \section ghs3d_advanced_parameters Advanced parameters
59 \image html ghs3d_parameters_advanced.png
61 \subsection advanced_meshing_options Advanced meshing options
63 Advanced page tab expose mostly useful advanced options. Initially,
64 default values of the options are displayed and they are not
65 modifiable. If an option is activated using a check-box, its value
68 <b>Add option</b> button adds a line to the table where you can type
69 an option and its value as text. A check box in the first column
70 activates/deactivates the option of the current row. A deactivated
71 option will be erased upon pressing \a Ok.
73 - <b>Gradation on skin</b> - This option set or not the gradation
74 value on the initial size of the skin vertices.
76 - <b>no</b> the gradation is not applied on the skin vertices.
77 In this case the initial size of a vertex is the average edges
78 lenght which belong the vertex.
80 - <b>yes</b> the gradation is applied on the skin vertices. In
81 this case the initial size of a vertex is the average edges
82 lenght which belong the vertex multiplied by the gradation.
85 - <b>Boundary regeneration</b> - defines the boundary regeneration mode.
86 MeshGems-Tetra uses alternative strategies for boundary regeneration.
88 - <b>standard</b> means that the standard boundary regeneration algorithm is used.
90 - <b>safe</b> means that various methods are tried as long as
91 the regeneration phase fails (including the alternate boundary
92 recovery mode), can be time consuming and can fail in very
95 - <b>recovery</b> means that the alternate boundary recovery
96 version is activated. Check <b>Using MeshGems-Tetra with the
97 boundary recovery module</b> chapter of MG-Tetra User Manual.
99 - <b>Force maximum edge size</b> - This option can be used to force
100 the desired maximum edge size in the generated mesh given by
101 the <b>Max Size</b> parameter. The default value is no, meaning that
102 the maximum edge length can be greater than the given value of
103 the <b>Max Size</b> parameter.
105 - <b>Force quadratic mesh</b> - This option permits to write or not an
106 output mesh file in case of negative Jacobians when generating a
107 quadratic mesh. Refer to section 4.6.3 for more details.
109 - <b>no</b> means that no output is written (this is the default);
111 - <b>yes</b> means that an output is written even in case of negative Jacobians.
113 - <b>Respect surface mesh</b> - This option forbids or not the
114 correction of input triangles and enforced edges mid-nodes to make
115 the element Jacobian strictly positive when generating a quadratic
118 - <b>yes</b> means that the input triangles and edges mid-nodes
119 are unchanged, the correction of nodes is only applied in the volume.
121 - <b>no</b> means that the input triangles and edges mid-nodes
122 can be moved. The correction of nodes is applied in the volume
123 and the mid-nodes correction can be applied on the input
124 triangles and edges mid-nodes. The corrected surface mid-nodes
125 are approximated on the surface first, or put on the linear
126 edges; The corrected edges mid-nodes can be put on the linear
129 - <b>Max number of errors</b> - the error messages will be printed up
130 to a given maximum number of errors. At least 1 error is printed and
131 at most 100 errors are printed to prevent infinite loops.
133 - <b>Maximal number of threads</b> - This allows to set the maximal
134 number of threads the software can use in parallel for the
135 multi-threading optimization mode.
137 - <b>No central point</b> - <b>yes</b> prevents adding an internal point at the
138 centre of gravity of the bounding box that MeshGems-Tetra uses by
139 default in order to speed up and to simplify the meshing
140 process. This option can be particularly useful to:
142 - generate a volume mesh without internal points at all;
144 - in some rare cases, help the boundary regeneration phase when
145 it failed with the standard options (for example when one
146 dimension of the domain is large compared to the other two with
147 a ratio of 20 or more). Use this option when the boundary
148 regeneration failed with the standard parameters and before
149 using the recovery version.
151 - <b>Optimise worst elements</b> - Applies an optimization processing
152 to improve the worst quality elements whenever possible.
154 - <b>Mode of pthreads</b> - This option sets the optimization mode
155 when using multithread capabilities. By default, this option is not
156 activated which means that only a sequential optimization is
159 - <b>safe</b> is slower than the sequential mode, but the
160 quality of the mesh can only improve;
162 - <b>aggressive</b> - is faster than the sequential mode, but
163 the quality of the resulting mesh may altered compared to the sequential mode.
165 - <b>Rectify jacobian</b> - This option activates correction of some
166 nodes so as to make the Jacobian of element strictly positive when
167 generating a quadratic mesh.
169 - <b>Sliver angle</b> - This options can be used to specify to
170 MeshGems-Tetra what is considered as a sliver and what is not. The
171 user has the possibility to specify an angle (in degrees), which
172 caracterizes a sliver : any tetrahedron which has at least an angle
173 below this value will be considered as a sliver.
175 - <b>Remove overconstrained tetrahedra</b> - This option can be used
176 to only split the tetrahadra which have at least two facets that
177 belong to the surface mesh. It will not split the overconstrained
178 edges in the mesh. The overconstrained tetrahedra are splitting,
179 whenever possible, which ensures that no tetrahedron has no more
180 than one boundary facet.
182 - <b>no</b> means that no correction is applied;
184 - <b>yes</b> means that the correction is applied after mesh generation;
186 - <b>only</b> means only correction is applied to an existing mesh.
188 - <b>Target quality</b> - Sets the desired maximum target of worst
189 quality acceptable for the volume mesh used during optimisation
190 phase. When defined, an optimization processing is applied to
191 improve the quality until the given target is reached whenever
192 possible. By default, this option is not activated which means that
193 only the standard optimisations are performed (the quality target is
194 the target quality computed by the program).
196 \subsection memory_settings Memory settings
198 - <b>Maximum memory size</b> - launches MG-Tetra software with
199 work space limited to the specified amount of RAM, in Mbytes. If this option is
200 checked off, the software will be launched with 7O% of the total RAM space.
202 - <b>Initial memory size</b> - starts MG-Tetra software with
203 the specified amount of work space, in Mbytes. If this option is checked off, the
204 software will be started with 100 Megabytes of working space.
206 \subsection log Logs and debug
208 - <b>Working directory</b> - allows defining the folder for input and output
209 files of MG-Tetra software, which are the files starting with "GHS3D_" prefix.
211 - <b>Verbose level</b> - to choose verbosity level in the range from
214 - 0, no standard output,
216 - 2, prints the data, quality statistics of the skin and final
217 meshes and indicates when the final mesh is being saved. In addition
218 the software gives indication regarding the CPU time.
220 - 10, same as 2 plus the main steps in the computation, quality
221 statistics histogram of the skin mesh, quality statistics histogram
222 together with the characteristics of the final mesh.
224 - <b>Print log in a file</b> - if this option is checked on the log is printed in a
225 file placed in the working directory, otherwise it is printed on the standard output.
227 - <b>Remove log on success</b> - if this option is checked on the log file is kept only
228 if an error occurs during the computation. This option is only available if <b>Print log in a file</b>
229 is enabled (there must be a log file to delete it) and <b>Keep all working files</b> is disabled
230 (in this case the log file is always kept).
232 - <b>Keep all working files</b> - allows checking input and output files
233 of MG-Tetra software, while usually these files are removed after the
234 launch of the mesher. The log file (if any) is also kept if this option is checked.
236 \ref ghs3d_top "Back to top"
238 \section ghs3d_enforced_vertices Enforced vertices
240 \image html ghs3d_enforced_vertices.png
242 MG-Tetra algorithm can locally make the mesh finer. It is possible to
243 define enforced vertices in the volume where the mesh will be detailed.
244 A node will be created at the enforced vertex coordinates.
246 An enforced vertex is defined by:
248 - from GEOM (Vertex, Compound) - only available on meshes with no
250 - or from (x,y,z) Cartesian coordinates
251 - A constant physical size. If this size is zero, then the mesh size is
253 - If a group name is given, the created node will be added to the
254 group. If the group does not exist, it is created.
256 \ref ghs3d_top "Back to top"
258 \section ghs3d_enforced_meshes Enforced Meshes
260 \image html ghs3d_enforced_meshes.png
262 MG-Tetra algorithm can be forced by other meshes, sub-meshes or
263 groups. The constraint elements should be contained
264 entirely into the solid mesh.
265 - The constraint element types are:
269 - If a group name is given, the enforced elements will be added to
270 the group. If the group does not exist, it is created.
272 <br><b>See Also</b> a sample TUI Script of the \ref tui_ghs3d "creation of a MG-Tetra hypothesis", including enforced vertices and meshes.
274 \ref ghs3d_top "Back to top"