This command produces a 2D mesh object from a 3D mesh object. A material interface, a plane , an isosurface or a network may be extracted. A plane may be defined by three points in the plane, by a vector normal to the plane, by three points on the axes of the space, or by the coefficients of the plane equation ax+by+cz=d. An isosurface is defined by the value of the surface and the mesh object attribute to test for this value. An interface is defined by the material(s) bounding the interface. region1, [region2]are the material numbers or the material region (mregion) names whose interface is to be extracted. Use -all- to extract from all interfaces. The pset syntax can be used to limit the action of the extract with the interface and network options only. The other options ignore pset. The output 2D mesh object is cmoout; the input 3D mesh object is cmoin.
A network is defined as the material interface network from the mesh object. Unlike the other extract forms, this extracts the “parent” interface and not the “child” interface, and ignores boundaries. The output cmo also contains a new attribute “map” which maps nodes in the output cmo to (parent) nodes in the input cmo. This is supposed to work for 2D meshes (tri, quad, or hybrid) in 2D or 3D and 3D meshes (tet, pyr, pri, hex or hybrid).
The surfmesh option is described by following the link: extract/surfmesh.
The output MO will be oriented such that the outward normal of the plane that defines the surface will point in the same direction as the normals for the triangles in the output MO. If the command extracts on an isosurface, the output MO will be oriented such that the normals for the triangles point in the direction of increasing field. If the command extracts on an interface, the output MO triangles will be oriented the same as the triangles extracted from region1 of the input MO. In the case of a plane extracted along all or a portion of a material interface, only those points that lie inside the material (i.e.: away from the direction of the normal) will be picked up. If the extraction is on a boundary, the normal to the extraction plane must point out of the material in order for points to be picked up.
extract /plane /threepts/x1,y1,z1/x2,y2,z2/x3,y3,z3/ifirst,ilast,istride/cmoout/cmoin
extract /plane /ptnorm/x1,y1,z1/xn,yn,zn/ ifirst,ilast,istride/cmoout/cmoin
extract /plane /axes/xv,yv,zv/ifirst,ilast,istride/cmoout/
extract /plane /abcd/a,b,c,d/ ifirst,ilast,istride/cmoout/cmoin
extract /isosurf/attribute/value/ ifirst,ilast,istride/cmoout/cmoin
- add an attribute to contain a field for refinement and extraction
* simple unit cube divided into 2 region by a horizontal plane
region/r1/ le cube and le mid /
mregion/m1/ le cube and lt mid /
region/r2/ le cube and gt mid /
mregion/m2/ le cube and gt mid /
- start out with just a few nodes
- put some values on the field
use refine to add more detail - note only linear interpolation
between the few original nodes - one would never really do this without
recalculating the field on the finer mesh
- extract a plane
- extract a plane - note pset is ignored!
- refine some more
- now get an isosurface
- get the boundary of one region
- get the interface between two regions
- try the network option
- get the surface mesh - note interface plane is included