X-Git-Url: http://git.salome-platform.org/gitweb/?p=modules%2Fsmesh.git;a=blobdiff_plain;f=doc%2Fsalome%2Fgui%2FSMESH%2Finput%2Fconstructing_meshes.doc;fp=doc%2Fsalome%2Fgui%2FSMESH%2Finput%2Fconstructing_meshes.doc;h=0000000000000000000000000000000000000000;hp=2481807fd0888fdda36ee1c0c880f28b4a8cb8c0;hb=f0f67c0b47e58361bc50c7169734da604fbfca01;hpb=f6825d843153c333e95e1345ef7c7fc2d0fe5698 diff --git a/doc/salome/gui/SMESH/input/constructing_meshes.doc b/doc/salome/gui/SMESH/input/constructing_meshes.doc deleted file mode 100644 index 2481807fd..000000000 --- a/doc/salome/gui/SMESH/input/constructing_meshes.doc +++ /dev/null @@ -1,483 +0,0 @@ -/*! - -\page constructing_meshes_page Constructing meshes - -To create a mesh on geometry, it is necessary to create a mesh object by choosing -- a geometrical shape produced in the Geometry module (main shape); -- meshing parameters, including - - \ref basic_meshing_algos_page "meshing algorithms" and - - \ref about_hypo_page "hypotheses" specifying constraints to be - taken into account by the chosen meshing algorithms. - -Then you can launch mesh generation by invoking \ref compute_anchor "Compute" command. -The generated mesh will be automatically shown in the Viewer. You can -switch off automatic visualization or limit mesh size until which it is -automatically shown in \ref mesh_preferences_page (Automatic update entry). - -\note Sometimes \a hypotheses term is used to refer to both algorithms -and hypotheses. - -Mesh generation on the geometry is performed in the bottom-up -flow: nodes on vertices are created first, then edges are divided into -segments using nodes on vertices; the nodes of segments are then -used to mesh faces; then the nodes of faces are used to mesh -solids. This automatically assures the conformity of the mesh. - -It is required to choose a meshing algorithm for every dimension of -sub-shapes up to the highest dimension to be generated. Note -that some algorithms generate elements of several dimensions, and -others of only one. It is not necessary to define meshing -parameters for all dimensions at once; you can start from 1D -meshing parameters only, compute the 1D mesh, then define 2D meshing -parameters and compute the 2D mesh (note that 1D mesh will not be -re-computed). - -An algorithm of a certain dimension chosen at mesh creation is applied -to discretize every sub-shape of this dimension. It is possible to -specify a different algorithm or hypothesis to be applied to one or -a group of sub-shapes by creating a \ref constructing_submeshes_page -"sub-mesh". You can specify no algorithms at all at mesh object -creation and specify the meshing parameters on sub-meshes only; then -only the sub-shapes, for which an algorithm and a hypothesis (if any) -have been defined will be discretized. - -\n Construction of a mesh on a geometry includes at least two -(\ref create_mesh_anchor "mesh creation" and -\ref compute_anchor "computing") of the following steps: - - -\anchor create_mesh_anchor -

Creation of a mesh object

-To construct a mesh: -
    -
  1. Select a geometrical object for meshing.
    2. -
  2. In the \b Mesh menu select Create Mesh or click "Create - Mesh" button in the toolbar. - -
    - \image html image32.png - "Create Mesh" button -
    - - The following dialog box will appear: - - \image html createmesh-inv.png -
    -
    3. -
  3. To filter off irrelevant meshing algorithms, you can - select Mesh Type in the corresponding list from Any, - Hexahedral, Tetrahedral, Triangular and \b Quadrilateral (there - can be less items for the geometry of lower dimensions). - - Selection of a mesh type hides all meshing algorithms that cannot - generate elements of this type.
    4. - -
  4. Apply \subpage basic_meshing_algos_page "meshing algorithms" and - \subpage about_hypo_page "hypotheses" which will be used to compute - this mesh. - - "Create mesh" dialog box contains several tab pages titled \b 3D, - \b 2D, \b 1D and \b 0D. The title of each page reflects the - dimension of the sub-shapes the algorithms listed on - this page affect and the maximal dimension of elements the algorithms - generate. For example, \b 3D page lists the algorithms that affect - 3D sub-shapes (solids) and generate 3D mesh elements - (tetrahedra, hexahedra etc.) - - As soon as you have selected an algorithm, you can create a - hypothesis (or select an already created one). A set of accessible - hypotheses includes only the hypotheses that can be used by the - selected algorithm. - - \note - - Some page(s) can be disabled if the geometrical - object does not include shapes (sub-shapes) of the corresponding - dimension(s). For example, if the input object is a geometrical face, - \b 3D page is disabled. - - Some algorithms affect the geometry of several dimensions, - i.e. 1D+2D or 1D+2D+3D. If such an algorithm is selected, the - dialog pages related to the corresponding lower dimensions are - disabled. - - \b 0D page refers to 0D geometry (vertices) rather than - to 0D elements. Mesh module does not provide algorithms that - produce 0D elements. Currently \b 0D page provides only one - algorithm "Segments around vertex" that allows specifying the required - size of mesh edges about the selected vertex (or vertices). - - For example, you need to mesh a 3D object. - - First, you can change a default name of your mesh in the \b Name - box. Then check that the selected geometrical object indicated in - \b Geometry field, is what you wish to mesh; if not, select - the correct object in the Object Browser. Click "Select" button - near \b Geometry field if the name of the object has not yet - appeared in \b Geometry field. -
    - \image html image120.png - "Select" button -
    - - Now you can define 3D Algorithm and 3D Hypotheses, which will be - applied to discretize the solids of your geometrical object using - 3D elements. Click the "Add Hypothesis" button to create - and add a hypothesis. -
    - \image html image121.png - "Add Hypothesis" button -
    - Click the "Plus" button to enable adding more additional hypotheses. - - Click the "Edit Hypothesis" button to change the values for the - current hypothesis. -
    - \image html image122.png - "Edit Hypothesis" button -
    - - Most 2D and 3D algorithms can work without hypotheses using - default meshing parameters. Some algorithms do not require any - hypotheses. After selection of an algorithm "Hypothesis" field of - the dialog can contain: - - After selection of an algorithm Add. Hypothesis field can contain: - - - Proceed in the same way with 2D and 1D Algorithms and Hypotheses that - will be used to mesh faces and edges of your geometry. (Note - that any object has edges, even if their existence is not - apparent, for example, a sphere has 4 edges). Note that the - choice of hypotheses and lower dimension algorithms depends on - the higher dimension algorithm. - - If you wish you can select other algorithms and/or hypotheses - for meshing some sub-shapes of your CAD model by \ref constructing_submeshes_page. - - Some algorithms generate mesh of several dimensions, while others - produce mesh of only one dimension. In the latter case there must - be one Algorithm and zero or several - Hypotheses for each dimension of your object, otherwise you will - not get any mesh at all. Of course, if you wish to mesh a face, - which is a 2D object, you do not need to define a 3D Algorithm and - Hypotheses. - - In the Object Browser the structure of the new mesh is - displayed as follows: - \image html image88.jpg - It contains: - - - There is an alternative way to assign Algorithms and Hypotheses by - clicking Assign a set of hypotheses button and selecting among - pre-defined sets of algorithms and hypotheses. In addition to the built-in - sets of hypotheses, it is possible to create custom sets by editing - CustomMeshers.xml file located in the home directory. CustomMeshers.xml - file must describe sets of hypotheses in the - same way as ${SMESH_ROOT_DIR}/share/salome/resources/smesh/StdMeshers.xml - file does (sets of hypotheses are enclosed between \ - tags). For example: -~~~~~~{.xml} - - - - - - - -~~~~~~ - If the file contents are incorrect, there can be an error at - activation of Mesh module: "fatal parsing error: error - triggered by consumer in line ..." -
    -
    - \image html hypo_sets.png - List of sets of hypotheses. Tag [custom] is - automatically added to the sets defined by the user. -
    - \note - - \a "Automatic" in the names of predefined sets of hypotheses - does not actually mean that they are suitable for meshing any - geometry. - - The list of sets of hypotheses can be shorter than in the - above image depending on the geometry dimension. -
    5. -
- -Consider trying a sample script for construction of a mesh from our -\ref tui_creating_meshes_page "TUI Scripts" section. - -\anchor evaluate_anchor -

Evaluating mesh size

- -After the mesh object is created and all hypotheses are assigned and -before \ref compute_anchor "Compute" operation, it is possible to -calculate the eventual mesh size. For this, select the mesh in -the Object Browser and from the \b Mesh menu select \b -Evaluate. The result of evaluation will be displayed in the following -information box: - -\image html mesh_evaluation_succeed.png - -\anchor preview_anchor -

Previewing the mesh

- -Before \ref compute_anchor "the mesh computation", it is also possible -to see the mesh preview. This operation allows to incrementally -compute the mesh, dimension by dimension, and to discard an -unsatisfactory mesh. - -For this, select the mesh in the Object Browser. From the \b Mesh menu -select \b Preview or click "Preview" button in the toolbar or activate -"Preview" item from the pop-up menu. - -
-\image html mesh_precompute.png -"Preview" button -
- -Select 1D mesh or 2D mesh preview mode in the Preview dialog. - -\image html preview_mesh_1D.png "1D mesh preview shows nodes computed on geometry edges" -
-\image html preview_mesh_2D.png "2D mesh preview shows edge mesh elements, computed on geometry faces" - -Compute button computes the whole mesh. - -When the Preview dialog is closed, the question about the storage of temporarily -created mesh elements appears: - -\image html preview_tmp_data.png - -These elements can be kept in the mesh. - - -\anchor submesh_order_anchor -

Changing sub-mesh priority

- -If the mesh contains concurrent \ref constructing_submeshes_page "sub-meshes", -it is possible to change the priority of their computation, i.e. to -change the priority of applying algorithms to the shared sub-shapes of -the Mesh shape. - -To change sub-mesh priority: - -Choose "Change sub-mesh priority" from the Mesh menu or a pop-up -menu. The opened dialog shows a list of sub-meshes in the order of -their priority. - -There is an example of sub-mesh order modifications taking a Mesh created on a Box -shape. The main Mesh object: - -The first sub-mesh Submesh_1 created on Face_1 is: - -The second sub-mesh Submesh_2 created on Face_2 is: - - -And the last sub-mesh Submesh_3 created on Face_3 is: - - -The sub-meshes become concurrent if they share sub-shapes that can be -meshed with different algorithms (or different hypotheses). In the -example, we have three sub-meshes with concurrent algorithms, because -they have different hypotheses. - -The first mesh computation is made with: -
-\image html mesh_order_123.png -"Mesh order SubMesh_1, SubMesh_2, SubMesh_3"
-
-\image html mesh_order_123_res.png -"Result mesh with order SubMesh_1, SubMesh_2, SubMesh_3 "
- -The next mesh computation is made with: -
-\image html mesh_order_213.png -"Mesh order SubMesh_2, SubMesh_1, SubMesh_3"
-
-\image html mesh_order_213_res.png -"Result mesh with order SubMesh_2, SubMesh_1, SubMesh_3 "
- -And the last mesh computation is made with: -
-\image html mesh_order_321.png -"Mesh order SubMesh_3, SubMesh_2, SubMesh_1"
-
\image html mesh_order_321_res.png -"Result mesh with order SubMesh_3, SubMesh_2, SubMesh_1 "
- -As we can see, each mesh computation has a different number of result -elements and a different mesh discretization on the shared edges (the edges -that are shared between Face_1, Face_2 and Face_3) - -Additionally, sub-mesh priority (the order of applied algorithms) can -be modified not only in a separate dialog box, but also in -the Preview. This helps to preview different mesh results, -modifying the order of sub-meshes. -
-\image html mesh_order_preview.png -"Preview with sub-mesh priority list box"
- -If there are no concurrent sub-meshes under the Mesh object, the user -will see the following information. -
-\image html mesh_order_no_concurrent.png -"No concurrent submeshes detected"
- - -\anchor compute_anchor -

Computing the mesh

- -It is equally possible to skip \ref evaluate_anchor "the Evaluation" -and \ref preview_anchor "the Preview" and to \b Compute the mesh after -the hypotheses are assigned. For this, select your mesh in -the Object Browser. From the \b Mesh menu or the context menu -select \b Compute or click \a "Compute" button of the toolbar. - -
-\image html image28.png -"Compute" button -
- -After the mesh computation finishes, the Mesh Computation information -box appears. If you close this box and click "Compute" button again, -without previously changing meshing parameters, the mesh will NOT be -re-computed and the Mesh Computation information box will be shown -with the same contents. (To fully re-compute the mesh, invoke -\ref clear_mesh_anchor "Clear Mesh Data" command before). - -\anchor meshing_result_anchor -If the mesh computation has been a success, the box shows information -on the number of entities of different types in the mesh. - -\image html meshcomputationsucceed.png - -\anchor meshing_failed_anchor -If the mesh computation has failed, the information about the cause of the -failure is provided in \b Errors table. - -\image html meshcomputationfail.png - -After you select an error in \b Errors table, Show Sub-shape button allows -visualizing in magenta the geometrical entity meshing of which failed -(Name of this entity or its ID and type is shown in \a Sub-shape column). - -
-\image html failed_computation.png -3D algorithm failed to compute mesh on a box shown using Show - Sub-shape button -
- -Publish Sub-shape button publishes the sub-shape, whose meshing -has failed, in the Geometry component as a child of the main shape, which -allows analyzing the problematic geometry and creating a sub-mesh on it in -order to locally tune the hypotheses. - -If the failure is caused by an invalid input mesh and the algorithm has -found which mesh entities are bad, Show bad Mesh -button appears in the dialog. Clicked, it shows the bad mesh entities in -the Viewer in magenta. Sometimes the shown mesh entities are too small -or/and hidden by other mesh elements. They can be seen after -switching the mesh to Wireframe visualization mode or switching off -the visualization of faces and volumes (if any). - -Bad Mesh to Group button creates groups of bad mesh entities -to facilitate their analysis. - -
-\image html show_bad_mesh.png -Edges bounding a hole in the surface are shown in magenta using Show - bad Mesh button -
- -\note Mesh Computation Information box does not appear if you set -\ref show_comp_result_pref "Mesh computation/Show a computation result notification" preference -to the "Never" value. This option gives the possibility to control mesh -computation reporting. There are the following possibilities: always -show the information box, show only if an error occurs or never. -By default, the information box is always shown after mesh computation operation. - -

-\anchor edit_anchor -

Editing the mesh

- -It is possible to \ref modifying_meshes_page "edit the mesh" of a -lower dimension before generation of the mesh of a higher dimension. - -For example you can generate a 2D mesh, modify it using e.g. -\ref pattern_mapping_page, and then generate a 3D mesh basing on the -modified 2D mesh. The workflow is as follows: -- Define 1D and 2D meshing algorithms. -- Compute the mesh. 2D mesh is generated. -- Apply \ref pattern_mapping_page. -- Define 3D meshing algorithms without modifying 1D and 2D algorithms -and hypotheses. -- Compute the mesh. 3D mesh is generated. - -\note Nodes and elements added \ref adding_nodes_and_elements_page -"manually" cannot be used in this workflow because the manually created -entities are not attached to any geometry and thus (usually) cannot be -found by the mesher paving a geometry. - -See Also a sample TUI Script demonstrates the possibility of -\ref tui_editing_while_meshing "Intermediate edition while meshing" - -*/