Convert

The Effect->Convert command in the Model module allows different types of conversions depending on the object selected.

• It converts faces or surfaces into different objects.
• It converts curves from one type to another.
• It converts a quad polygon mesh into a triangulated polygon mesh.

Faces

You can convert a face to:

• A 2D polygon mesh
• A face made from a Linear type curve
• A NURBS face

You can control the resolution of the newly created object, both the exterior contour and any holes in the object.The original face remains available.

Procedure

1. Select a face.
2. Choose the Effect->Convert command. The Convert Face dialogue box is displayed.
3. Select either Polygon (polygon mesh), Linear Face, or NURBS.

• If you select a B-Spline face, for example, you can convert it to a cubic NURBS face or a face made of a Linear curve.
• If you select a NURBS face of higher degree (quadratic or cubic), and choose the Linear face option, the NURBS face is converted to a NURBS face of linear degree.
• If you choose the Polygon option, the face is converted to polygon mesh face.

4. To change the resolution of a curve (either a Hole or the Exterior curve), select the curve in the scroll box and enter a new Step value. The Step value applies only to the selected curve. To modify the Step value for all curves, you need to repeat the conversion procedure.
5. If you are satisfied with the shape of all curves of your original face, then leave the Step value near the default of 10.
6. Click Ok to accept the settings or Cancel to exit the dialogue box.

Parameters

• Scroll Box lists the curves of the face.
• Polygon converts a face into a 2D polygon mesh object.
• Linear Face converts a Bezier, Cardinal, or B-Spline face to a face of Linear curve type. It also converts a NURBS face to a NURBS face of linear degree.
• NURBS converts a Bezier, Cardinal, or B-Spline face to a NURBS face.
• Exterior Step specifies the number of steps for the subdivision of converted curves.

Curves

It may be useful to convert a curve from one type to another to perform a particular operation. For example if you wanted to project a curve onto a surface or trim a surface, this can only be done using a NURBS curve. If your original curve was drawn as a Bezier, you could convert it to a NURBS.

The Effect->Convert command converts curves from one type to another by one of the following methods.

 

Procedure

1. Select a curve.
2. Choose the Effect->Convert command.
   
   The Convert Curve dialogue box is displayed.
   
   
3. Select either Keep Control Points or Keep Curve and select the new type of curve.
   
   If you keep the control points, the shape of the curve may change as it is converted. Conversely, if you keep the curve's shape, the number of points on the curve are not the same after the conversion.
   
   
4. Click Ok to accept the settings or Cancel to exit the dialogue box.
   
   The curve is converted according to your settings, and the original curve is preserved.

Parameters

Keep Control Points

Converts curves according to the number of control points. Any type of curve can be converted to another curve type, but the shape of the curve is modified.

Keep Curve

Converts any type of curve into Linear, Bezier, or NURBS, while closely maintaining the appearance of the curve. Only the conversion choices in which the curve shape can be maintained are offered.

• Linear:

If you are converting a NURBS curve of higher degree (quadratic or cubic) to Linear, the result is a NURBS curve of linear degree.

B-Spline, Cardinal and Bezier curves are converted to linear type curves.

The Subdivision value determines the sampling of the original (higher degree) curve when converting to a linear curve. The higher the sampling value, the more faithfully the resulting linear curve follows the shape of the original.

If you are satisfied with the shape of your original curve, and you want to convert it to linear, leave the Subdivision value high.

• Bezier sets the Maximum Error, which controls the deviation of the Bezier from the original shape of a linear curve. The smaller the value, the more accurate the shape.
• NURBS converts a non-NURBS curve into a NURBS curve while preserving its shape.

 

Patch Objects

You can convert a patch surface object to a NURBS surface or a polygon mesh object.

1. Select a patch object.
2. Choose the Effect->Convert command.
   
   The Convert Patch dialogue box is displayed.
   
   
3. Select either Polygon or NURBS for the new object type.

The object is converted to a NURBS surface or a polygon mesh object.

 

NURBS Surface Object

You can convert a NURBS surface to a polygon mesh object.

1. Select a NURBS surface object.
2. Choose the Effect->Convert command.

The surface object is immediately converted to a polygon mesh object.

 

Polygon Mesh Object

You can convert a quad polygon mesh object to a triangulated polygon mesh object.

1. Select a quad polygon mesh object.
2. Choose the Effect->Convert command.

The polygon mesh object is immediately triangulated.

Last updated 02-apr-1998