All the options described here can be set using the MEDCouplingRemapper::setOptionInt, MEDCouplingRemapper::setOptionDouble, and MEDCouplingRemapper::setOptionString methods.

Special features of 2D intersectors

P0->P0 : PlanarIntersector.

All the 2D intersectors inherits from INTERP_KERNEL::PlanarIntersector class.

The main task offered by this class is to give the evaluation of the interpolation of one cell in source mesh with an another cell in the target mesh.

P0->P0 intersectors features.

When remapping two dimensional fields, areas of intersection between polygonal cells are to be computed. Three algorithms are available:

Triangulation: decompose each cells into triangles and computes triangle-triangle intersection by determining segment crossings and node inclusions. This algorithm is the fastest if both meshes are made of triangular cells.
Convex: presume that both meshes are made of convex cells, and performs a direct computation of the intersection nodes between two cells through a sweep line algorithm (see F. Preparata and M. Shamos, 1985 in References). For the moment, it is only possible to remap two dimensional fields on meshes with mixed triangular and quadrangular elements.
Geometric2D: Any type of 2D cells (linear, quadratic, convex-polygons, non-convex polygons) is supported by this algorithm. Due to its flexibility this algorithm is slower than the other.
PointLocator: This is a non conservative interpolator. For P0P0, it locates the barycenter of target cell in the source cells. For P1P0, it locates barycenter of target cell and compute barycentric coordinates in source cell (Works only with Triangulation). For P0P1 locate target nodes in source cells. For P1P1 compute for each target node its barycentric coordinates in source cell.

The following options are available for the 2D intersection computations:

Option	Description	Admitted values	Default
Intersection_type	Specifies the algorithm to be used in the computation of the cell-cell intersections	Triangulation, Convex, Geometric2D, PointLocator	Triangulation
Precision	Accuracy of the computations is precision times the characteristic size of the meshes	positive real numbers	1.0E-12
PrintLevel	Level of verboseness during the computations	0, 1, 2, 3	0

Special features of 3D surface intersectors

When remapping a three dimensional surfaces, one should give a meaning to the area of intersection between two three-dimensional non coplanar polygons. A projection phase is thus necessary to have both polygons on the same plane. Care must be taken when defining this projection to avoid non conservative remappings. After the projection step, the source and target cells lie in the same plane and the same algorithms as for 2D remapping can be employed. For the moment, it is only possible to remap fields on three dimension surface meshes with mixed triangular and quadrangular elements. Similar options as for the 2D remapping are available, plus some additional options specific to 3D surface remapping:

Option	Description	Admitted values	Default
MedianPlane	Position of the median plane where both cells will be projected	real numbers between 0 and 1	0.5
Precision	Accuracy of the computations is precision times the characteristic size of the meshes	positive real numbers	1.E-12
Orientation	Specifies orientation to take into account. If -1 only negative intersection area are taken into account. If 1 only positive intersection area are taken into account. If 0 intersection area are always taken into account. If 2 intersection area are always taken into account (as 0) difference is that absolute value	-1,0,1,2	0
DoRotate	Performs a rotation of the coordinate system such that the median plane is the Oxy plane	boolean true or false	true
BoundingBoxAdjustment	When detecting an intersection between bounding boxes, the bounding are expanded by a factor (1+BoundingBoxAdjustment). It is particularly useful when detecting intersections for 3D surfaces for which the bounding boxes might not actually intersect.	positive real numbers	1.e-4
BoundingBoxAdjustmentAbs	When detecting an intersection between bounding boxes, the bounding are expanded uniformly in the 3 dimension of space with the absolute value BoundingBoxAdjustmentAbs. It is particularly useful when detecting intersections for 3D surfaces for which the bounding boxes might not actually intersect.	positive real numbers	0.
MaxDistance3DSurfIntersect	Before attempting an intersection in 3D surf test the distance D between fast barycenter of target cell and medium source plane P. If option < 0. no interpretation of D is done. If option > 0. then if D<option intersection is taken into account and if D>option intersection is equal to 0. . This option exists in order to have an iso behaviour whatever the angle of plane P and OXY OYZ OXZ contrary to BBoxAdjestments options.	real numbers	-1.

Note that choosing the Triangulation Intersection_type necessarily set the DoRotate option to true.

Special features of 3D volumes intersectors

P0->P0 : TargetIntersector

Unlike PlanarIntersector phylosophy this intersector is slightly different. Here for the moment there is one instance per pair of meshes and target element. See INTERP_KERNEL::TargetIntersector for more details.

P0->P0 intersectors features.

When remapping three dimensional fields, volumes of intersection between polyhedral cells are to be computed. Two methods are available :

Triangulation : the method of Jeffrey Grandy, 1999 (see References) to intersect arbitrary polyhedra. The basic algorithm computes the intersection of a tetrahedron with an arbitrary (possibly non convex) polyhedron. Using splitting techniques, it is possible to transform the problem of computing the intersection between two general polyhedra into several tetrahedron-polyhedron intersection calculations. For the moment it is only possible to remap fields on meshes having mixed tetrahedral and hexahedral cells. When using a mesh with hexahedral cells, several splitting techniques may be employed depending mainly on whether the faces are planar or not. The following options are available for the splitting:

PointLocator : non conservative intersector based on the same principle than described in 2D.

Option	Description	Admitted values	Default
Intersection_type	Specifies the algorithm to be used in the computation of the cell-cell intersections	Triangulation, PointLocator	Triangulation
SplittingPolicy	Way in which the hexahedra are split into tetrahedra (only if Intersection_type==Triangulation)	PLANAR_FACE_5, PLANAR_FACE_6, GENERAL_24, GENERAL_48	PLANAR_FACE_5
PrintLevel	Level of verboseness during the computations	1, 2, 3, 4, 5	0

Note that a SplittingPolicy values starting with the word "PLANAR" presume that each face is to be considered planar, while the SplittingPolicy values starting with the word GENERAL does not. The integer at the end gives the number of tetrahedra that result from the split. Consider an hexahedron with planar faces and nodes numbered according to the following picture:

              7 ------ 6
             /|       /|
            / |      / |
           3 ------ 2  |
           |  |     |  |
           |  |     |  |
           |  4-----|- 5
           | /      | /
           0 ------ 1

The use of the SPLIT_NODES_5 splitting policy would lead to a 5 tetrahedra decomposition as follows :

  0, 1, 5, 2
  0, 4, 5, 7
  0, 3, 7, 2
  5, 6, 7, 2
  0, 2, 5, 7

The use of the SPLIT_NODES_6 splitting policy would lead to a 6 tetrahedra decomposition as follows :

  0, 1, 5, 6
  0, 2, 1, 6
  0, 5, 4, 6
  0, 4, 7, 6
  0, 3, 2, 6
  0, 7, 3, 6