FEM Patch Face
Insert 
Shapes (Standard) (Part Level)
Use this command to fit a
single face through a set of points on boundary curves. This is similar
to the N-Sided
Patch command, but instead of subdividing the patch into 4-sided NURBS
faces first, a surface is directly fitted through a collection of points
on the boundary curves, then trimmed along the boundary.
This method produces favorable results for the cases when creating a well-formed 4-sided patch is a problem, such as input curves that resemble the outline of a "clover leaf." The N-Sided Patch does not handle filling a face along a set of boundary edges that include concave curves.
Curves - Select the boundary curves. You can use wireframe geometry, sketches or face edges.
U degree, V degree - Specify the degree of the resulting face in the U and V directions. This refers to the degree of the equation that defines the face in each direction. Faces of a lesser degree are less exact and require less storage and computation time. The opposite is true for faces of a higher degree. The default value of 3 will produce a good quality face in most cases.
Points
You can select interior points that you want the new face to pass through. This can be any list of points and/or point blocks as long as they are "within" the boundary curves.
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The fitted face will follow the general "ridge lines" defined by the spine curves, thus forming a roof-like face. The ridge lines can consist of a single point for a pointy tipped dome in its simplest form or a series of complex ridge lines and valleys. |
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Normal
If the Points option above is used, you can specify an optional surface normal at these points. This can help create "uniform" spine ridge lines for domed face features. This forces the ridge lines to be the peak of the dome and point in an uniform direction. Otherwise, undulations may occur.
Tangent at Boundary
Check this box to make the face tangent to all edges attached to a face. Tangency tags (see below) will override this option.
Specify sample density
If you check this box - In the Density field (see below), enter the average number of sampling points on the input curves. VX then computes the actual number of sampling points according to the relative length of each curve with regards to the total length of all curves. This is a rather quick but simplistic approach. However, it may result in exceeding the desired point tolerance limit at a location between two adjacent sample points when interpolated unless a very high number of points are used. Therefore, some trial and error may be necessary.
If you do not check this box - VX automatically uses a discretization method for sampling the points on the input curves. This is an attempt to automatically generate the sample points in such a way where no chord between the points is further away from the curve than the point tolerance limit and thus, increases the accuracy of the resulting fitted face. You may also use the Iteration option (see below) along with this option to specify the number of iterations used during discretization for fine-tuning purposes.
Density
See Specify sample density above.
Iterations
Specify the number of iterations used for locating sample points on the input curves. See Specify sample density above.
U-direction
Indicate the preferred U-Direction for the face.
FEM Settings
Spring Constant, Bending Resistance
These commands create surfaces based on energy minimization. Use the slider bars to set the spring constant and bending resistance values. See Finite Element Methods (FEM) for Surface Creation for more information.
Reset
Use this option to reset the FEM Settings sliders to their system default positions.
Add Tangency
Use this option to add a tangency tag to the edge of one or two mating faces that indicates the tangency at the edge. A tag can be added during or after (not before) boundary edges are selected. A tangency tag can not be added to an edge that has not yet been selected as a boundary. Tangency tags created with this option will override the "Tangent at boundary" option (above) for the tagged edge.
Select the edge to tag.
If the edge is shared by two faces, select the face to tag. If you middle-click, a random face is assigned.
Select the continuity option.
Position - Only the position of the edge is maintained.
Tangent - The position of the edge and tangency (at the edge) are enforced.
Delete Tangency
Use this option to delete a continuity tag created with the Add Tangency option above. Select the edge that the continuity tag is attached to.
The maximum number of control points for the given fitted face is approximately 100,000 (9 minimum). This number allows more complex surfaces to be fitted without overly sacrificing system performance.
