Creating a Point Cloud surface by fitting a set of points

The Surface Type Fit cloud of points option of the Point Cloud command enables you to create a surface by fitting a given set of points or an existing surface.
A reference surface is used by the application in order to obtain the final surface. The reference may be either an existing surface of the model, or a stretched virtual one, not actually existing in the model but identified through its boundaries (four or three: in the latter case a segment is considered as the fourth boundary), or through four vertices.
After starting the command, proceed as follows.

1	If not already selected, in the Surface Type drop-down list select Fit cloud of points.
2	In the Input Mode drop-down list, select the method to be used: Select To create a surface by fitting a set of point entities existing in the model. When this mode is selected, first of all you will have to select the point entities (by clicking or by using a selection operator). Once the points are selected, the Fitting Mode must also be specified, by choosing one of the following: Boundary curves When this option is selected, the reference surface used by the program to compute the fitted surface is a stretched surface with its boundaries coinciding with the curves you will have to select. See "Creating a Point Cloud surface by specifying boundary curves" for details. 4 Vertices When this option is selected, the reference surface used by the program to compute the fitted surface is a stretched surface with its vertices coinciding with the points you will have to select. See "Creating a Point Cloud surface by specifying four vertices" for details. Surface based When this option is selected, the reference surface used by the program to compute the fitted surface is an existing surface you will have to select. See "Creating a Point Cloud surface by specifying a reference surface" for details. Import points from ASCII file To create a surface by fitting a set of point entities contained in ASCII file (extension ".pt"; each line in the file must contain the three world coordinates of a point; each coordinate is separated by the following through a blank character). The coordinates will be read according to the Units of measurement that you can set. Once the file containing the point has been loaded, the Fitting Mode must also be specified, by choosing one of the methods described for the Select mode. Fit surface To create a surface by fitting an existing surface to be selected. See "Creating a Point Cloud surface by fitting an existing surface" for details. Points from curves To create a surface by fitting the points lying on some curves to be selected. You can also define the No. of points per curve to be fitted.
3	Under NURBS parameters, you can set the values for the resulting surface. The values you can actually define depend on your former choices. The whole set is the following: Deg. U Degree of the surface along the U parametric direction. Cont. U Continuity value of the surface along the U parametric direction. Deg. V Degree of the surface along the V parametric direction. Cont. V Continuity value of the surface along the v parametric direction. Arcs U Number of arcs of the surface along the U parametric direction. Arcs V Number of arcs of the surface along the V parametric direction.
4	Once you have completed the necessary selections and set the parameters as you like, you can click the Preview button ( ). The preview of the resulting surface will be displayed. The fitting parameters will also be displayed: Max. distance the distance of the point that is farthest away from the fitting surface, which you can display by selecting the Most distant point check box. Mean square error Let di be the distance of the point Pi from the fitting surface and n the number of points to be fitted. The mean square error Eqmis the following:   You can iterate the fitting process by clicking Mean square error, thus reducing the above said values. The number of iterations can also be set (in the No. of iterations box). Finally, You can have a preview of the control points for the resulting surface by checking the Show Control Points box.
5	Click or to confirm your selections and create the surface, or click to discard your changes.