Surface Fitting

Purpose:

This command allows user to fit surface from mesh/nodes/curves. There are 5 methods included in this dialog for surface fitting: surface fitting by mesh, surface fitting by nodes, surface fitting by curves, surface fitting by mesh&curves and surface fitting by primitives.

Function:

Mesh : Create surface from mesh or sub-mesh defined by a boundry loop.

Nodes :Create surface from nodes/points.

Curves : Create surface from curves, for example, contour curves.

Mesh&Curves : Create multiple surfaces from mesh and the curve network defined on the mesh.

Primitives : Create primitives from mesh or nodes.

Sample:

Single surface creation from mesh : A tutorial to create a single surface from mesh.

Surface creation from sub-mesh : A tutorial to create a single surface from sub-mesh.

Surface creation from curves : A tutorial to create a single surface from multiple curves.

Multiple surfaces creation from mesh : A tutorial to create multiple surfaces from mesh.

Watertight surfaces creation from mesh : A tutorial to create watertight surfaces from mesh.

Mesh

dialog
  • Topologye : Choose the topology type of your selected mesh model. Currently, there are two types of topology for choice: 1. plane-homoeomorphous; 2 cylinder-homeomorphous. LSPP use the primitives of the topology type as a template for surface creation. When you choose cylinder-homeomorphous , Boundary curves for surface and Untrimmed boundary will be disable.

  • Mesh : Use General Selection Interface to select a mesh. This checkbox allows user to select the mesh model for surface creation.

  • Boundary curves for surface : in case that user has selected a mesh model and wants to create surface from any sub-mesh region, this checkbox lets user select a boundary loop to define the inner region as a sub-mesh .

  • Gap Tol : Tolerance threshold for the end point connection for selected boundary curves .

 

  • Set control point number : This checkbox helps you specify surface UV control point number or not. By default, users do not need to care the surface uv control point number, program will compute a reasonable number for surface creation. However, for thoes advanced users who understand the feature of uv control point number very well, this checkbox is helpful for them to specify their desired number for better surface generation. When this checkbox is checked, the two textfield U Ctl Points and V Ctl Points will be enabled. The following picture shows U-direction and V-direction for a NURBS surface.

  • U Ctl Points : surface control point number in U-direction. This number will be used as an initial number to create the surface. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in U-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300 .

  • V Ctl Points : surface control point number in V-direction. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in V-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300 .

 

  • U Degree : surface degree number in U-direction. The default surface degree is 3. The maximum degree number is 8 .

 

  • V Degree : surface degree number in V-direction. The default surface degree is 3. The maximum degree number is 8 .

 

  • Max Tol : threshold for the maximum tolerance between the selected nodes/mesh and the final surface. The default number is 0.5. User can adjust this number for higher or lower precision .

 

  • Ave Tol : average tolerance between the selected nodes/mesh and surface reported by the program .

 

  • Smoothness : smoothness factor for surface generation. This factor helps user control surface smoothness, also this parameter effects surface precision. Little smoothness factor number results in little weight on surface smoothness and more weight on high presion; High smoothness factor effects oppositely. Usually, the default number is ok for general surface generation .

 

  • Untrimmed boundary : this checkbox only works for the case that the Boundary curves for surface is checked for sub-mesh surface creation. In this case, if this checkbox is checked, the program will detect automatically 4 sharp corners for a surface and the surface will be created as a untrimmed surface. Therefore, the boundary curves are kept as iso-line in U-direction and V-direction .

If this button is not checked, a trimmed surface will generate as shown as the following picture, and the boundary line may not be iso-line.

  • Preview : This button helps user preview surface. User can preview surface by the default parameters setting or preview a new surface by modification of the parameters such as Ref Plane Diretion £¨ dx, dy, dz £© (for Surface by Nodes ), surface uv control point number, surface degree number, maximum tolerance threshold or smoothness factor .

 

  • Fit : This button helps user get a high precision under the threshold of maximum tolerance. After user click Preview button, this button will be enabled in case that the initial surface was created successfully, and a message about the surface data will be printed in the message dialog. Usually, the maximum tolerance of this initial surface may not reach the specified threshold value. Then user can click this Fit button to get higher precision. Sometimes, user needs to click this button by several time for their desired precision .
  • Apply : After user has gotten a satisfactory surface by clicking Preview button and Fit button continuously, clicking this button will let user accept the surface and add it into database. Atfer the surface was added into database, Undo button will show .

  • Undo : click this button to remove the accepted surface from database .

  • Close : Close this dialog.

Nodes

dialog
  • Ref Plane Direction(dx, dy, dz) : Normal direction (dx, dy, dz) of a refered plane. When you create surface by selecting nodes(points), program will calculate a plane with this normal direction (dx, dy, dz) automatically. This plane is used as reference for surface fitting. Surface is created by projecting your selected nodes(points) onto this refered plane and draped them to target position by least mean square fitting solution.This refered plane plays an important role for surface generation. Different plane normal direction will result in different surface. Program can often calculate a reasonable direction when you click Preview button at first time. However, you can still adjust this direction (dx, dy, dz) and click Preview button for better surface result .

  • Nodes :Select nodes for surface creation.
  • Base surface :Select a base surface as a template for surface fitting. This checkbox is optional. If a base surface is selected, the final surface is calculated by moning the base surface to the selected nodes.
  • Set control point number :This checkbox helps you specify surface UV control point number or not. By default, users do not need to care the surface uv control point number, program will compute a reasonable number for surface creation. However, for thoes advanced users who understand the feature of uv control point number very well, this checkbox is helpful for them to specify their desired number for better surface generation. When this checkbox is checked, the two textfield U Ctl Points and V Ctl Points will be enabled. The following picture shows U-direction and V-direction for a NURBS surface.
  • U Ctl Points :surface control point number in U-direction. This number will be used as an initial number to create the surface. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in U-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300 .

  • V Ctl Points : surface control point number in V-direction. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in V-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300.

 

  • U Degree : surface degree number in U-direction. The default surface degree is 3. The maximum degree number is 8 .
  • V Degree : surface degree number in V-direction. The default surface degree is 3. The maximum degree number is 8 .
  • Max Tol : threshold for the maximum tolerance between the selected nodes/mesh and the final surface. The default number is 0.5. User can adjust this number for higher or lower precision .
  • Ave Tol : average tolerance between the selected nodes/mesh and surface reported by the program .
  • Smoothness : smoothness factor for surface generation. same as in Surface by Mesh option .
  • Untrimmed boundary : this checkbox is disable for this option .
  • Preview : this button helps user preview surface. After user click preview , program will calculate a resonable Ref Plane Direction and display the vector in the textfield of £¨ dx, dy, dz £© , resonable UV control point number is evaluated too. User can modify thoes parameters and click Preview button to change the surface .
  • Fit : This button helps user get a high precision under the threshold of maximum tolerance. After user click Preview button, this button will be enabled in case that the initial surface was created successfully, and a message about the surface data will be printed in the message dialog. Usually, the maximum tolerance of this initial surface may not reach the specified threshold value. Then user can click this Fit button continously to get higher precision. UV control point number will be kept for Surface by Nodes option and Surface by Curves option .
  • Apply : After user has gotten a satisfactory surface by clicking Preview button and Fit button continuously, clicking this button will let user accept the surface and add it into database. Atfer the surface was added into database, Undo button will show .

  • Undo : click this button to remove the accepted surface from database .

  • Close : Close this dialog.

Curves

dialog
  • Ref Plane Direction(dx, dy, dz) : Normal direction (dx, dy, dz) of a refered plane. When you create surface by selecting nodes(points), program will calculate a plane with this normal direction (dx, dy, dz) automatically. This plane is used as reference for surface fitting. Surface is created by projecting your selected nodes(points) onto this refered plane and draped them to target position by least mean square fitting solution.This refered plane plays an important role for surface generation. Different plane normal direction will result in different surface. Program can often calculate a reasonable direction when you click Preview button at first time. However, you can still adjust this direction (dx, dy, dz) and click Preview button for better surface result .

  • Nodes : disable in this option.
  • Base surface : disable in this option.
  • Set control point number :This checkbox helps you specify surface UV control point number or not. By default, users do not need to care the surface uv control point number, program will compute a reasonable number for surface creation. However, for thoes advanced users who understand the feature of uv control point number very well, this checkbox is helpful for them to specify their desired number for better surface generation. When this checkbox is checked, the two textfield U Ctl Points and V Ctl Points will be enabled. The following picture shows U-direction and V-direction for a NURBS surface.
  • U Ctl Points :surface control point number in U-direction. This number will be used as an initial number to create the surface. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in U-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300 .
  • V Ctl Points : surface control point number in V-direction. When you create S urface by Mesh , the final surface control point number is often greater than this initial number; However, when you create S urface by Nodes , the final surface control point number in V-direction is same as your input number. The default number is 21 if it is activated. The maximum number is 300.

 

  • U Degree : surface degree number in U-direction. The default surface degree is 3. The maximum degree number is 8 .
  • V Degree : surface degree number in V-direction. The default surface degree is 3. The maximum degree number is 8 .
  • Max Tol : threshold for the maximum tolerance between the selected nodes/mesh and the final surface. The default number is 0.5. User can adjust this number for higher or lower precision .
  • Ave Tol : average tolerance between the selected nodes/mesh and surface reported by the program .
  • Smoothness : smoothness factor for surface generation. same as in Surface by Mesh option .
  • Untrimmed boundary : this checkbox is disable for this option .
  • Preview : this button helps user preview surface. After user click preview , program will calculate a resonable Ref Plane Direction and display the vector in the textfield of £¨ dx, dy, dz £© , resonable UV control point number is evaluated too. User can modify thoes parameters and click Preview button to change the surface .
  • Fit : This button helps user get a high precision under the threshold of maximum tolerance. After user click Preview button, this button will be enabled in case that the initial surface was created successfully, and a message about the surface data will be printed in the message dialog. Usually, the maximum tolerance of this initial surface may not reach the specified threshold value. Then user can click this Fit button continously to get higher precision. UV control point number will be kept for Surface by Nodes option and Surface by Curves option .
  • Apply : After user has gotten a satisfactory surface by clicking Preview button and Fit button continuously, clicking this button will let user accept the surface and add it into database. Atfer the surface was added into database, Undo button will show .

  • Undo : click this button to remove the accepted surface from database .

  • Close : Close this dialog.

Mesh&Curves

dialog
  • Topology : this is disable in this option.

  • Mesh : Use General Selection Interface to select a mesh, this checkbox allows user to select the mesh model for surface creation .

  • Boundary curves for surface : click this checkbox to select the curve network attached on the mesh model. The curve network will be kept as surface boundary line .

  • Gap Tol : The segment is morphed by constraint of general smooth.

  • Layout : click this button, program will create base surfaces according to the topology information of curve network. The base surfaces will cover the mesh model, but they are not fitted to mesh nodes very well. The following picture shows the base surfaces .

  • New : after Layout button was clicked and base surfaces generated successfully, this New button will be activated. This button lets user select boundary curves and create a new face .

  • Max Tol : threshold for the maximum tolerance between the selected nodes/mesh and the final surface. The default number is 0.5. User can adjust this number for higher or lower precision .
  • Ave Tol : average tolerance between the selected nodes/mesh and surface reported by the program .
  • Smoothness : smoothness factor for surface generation. same as in Surface by Mesh option .
  • Untrimmed boundary : this checkbox is disanble for this option .
  • Preview : this checkbox is disanble for this option .
  • Fit : This button helps user get a high precision under the threshold of maximum tolerance .
  • Apply : clicking this button will let user accept the surface and add it into database. Atfer the surface was added into database, Undo button will show .

  • Undo : click this button to remove the accepted surface from database .

  • Close : Close this dialog.

Primitives

dialog
  • Nodes : select nodes for primitives creation.

  • Mesh : select mesh for primitives creation.

  • Primitives : select type of primitives for creation.

  • Apply : clicking this button will let user accept the surface and add it into database. Atfer the surface was added into database, Undo button will show .

  • Undo : click this button to remove the accepted surface from database .

  • Close : Close this dialog.