a sample demonstrate how to fit a NURBS surface to mesh.
Open the demo file meshtosurface.proj . You will see the following mesh model displayed in LSPP mainpage.
a mesh model
Click the menu button Geometry->Surface->Fit from pnts/mesh . Both of Fit surface from Points/Mesh dialog and Mesh Selection dialog are shown .
dialog for selecting mesh
Select Mesh Option. Select ByPart radio button in the Selection panel.
mesh option
Click Preview button. An initial surface generated. See the following two pictures, the right picture shows the initial surface, the left picture shows the details at the corner position.
preview surface
Also a message was printed in the bottom dialog : Control point #:u=21 v=31; max dev:0.439477,mean dev:0.104203 . This message reports that the initial surface has 21 control points in U-direction and 31 control points in V-direction, the maximum deviation between surface and mesh nodes is 0.439477, the mean deviation is 0.104203. The maximum deviation is under the default threshold setting 0.5 .
tolerance
Change the parameter Max Tol to be 0.3. Click Fit button again. The surface was updated. The message reports ¡®Control point #:u=27 v=38; max dev:0.256196,mean dev:0.054895.
Change the parameter Max Tol to be 0.1. Click Fit button again. surface was updated. The message reports ¡®Control point #:u=33 v=43; max dev:0.093604,mean dev:0.016271'. You will see the the updated surface is very near to the corner point position from the following picture.
improved surface
Change the parameter Max Tol to be 0.05. Click Fit button again. surface was updated. The message reports ¡®Control point #:u=40 v=48; max dev:0.049742,mean dev:0.009516'.
When you decrease the max tolerence threshold, the surface control point number will increase in both of U-direction and V-direction in order to get more details for higher precision.
When you get the satisfactory surface, click Apply button to add the surface into database.