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Example: Using Different Offset Methods
The following figure illustrates the difference in the offset geometry created through the Normal to Surface, Controlled Fit, and Automatic Fit methods. In this example, the Controlled Fit method allows you to select the coordinate system for translation and restrict the translation of the scaled geometry along the y-axis such that the resulting quilt terminates at the same level as the original quilt. Note that the resulting radius of curvature differs depending on the offset type used.
Using different offset methods
1. Original quilt
2. Offsets from the original quilt
3. Using Normal to Surface
4. Using Controlled Fit
5. Using Automatic Fit
6. Using Controlled Fit
7. Using Normal to Surface
8. Using Automatic Fit
Recommendations for using the offset methods:
If Normal to Surface fails, use Automatic Fit. The Automatic Fit method automatically calculates the best directions to translate the surfaces such that they appear as original ones. However, this method does not guarantee a uniform offset normal to surfaces. If the results of Automatic Fit are not satisfactory, use Controlled Fit to aid in calculation.
It is recommended that you use Automatic Fit and Controlled Fit with convex geometry only. These methods involve scaling of geometry. For non-convex geometry, the offset distance may vary, as shown in the following figure.
Offsetting Complex Surface Shapes
1. Original surface
2. Resulting surface using Automatic Fit
3. Resulting surface using Normal to Surface
When you use Automatic Fit or Controlled Fit to create an offset, the system attempts to make the distance between the original and the offset quilt no less than the input value.
The location of the coordinate system that you select when using Controlled Fit affects how the quilt is scaled. In the following illustration, the offset quilt is created using Controlled Fit with the translation restricted along the x- and y-axes. In illustration a, scaling is with respect to the CS0 coordinate system, while scaling is with respect to the CS3 coordinate system in illustration b. Note that the location of the coordinate system determines which edges remain coplanar.
a. Offset created using CS0
1. Original quilt
2. Offset quilt
1. Coplanar vertices, translation is not allowed along the x-axis
2. Original quilt
3. Coplanar vertices, translation is not allowed along the y-axis
The edges and vertices on the plane that passes through the origin of the CS0 coordinate system (the yz- and xz-planes, respectively) remain fixed. This is because translation is not allowed along the x- and y-axes.
b. Offset created using CS3
1. Coplanar vertices, translation is not allowed along the x-axis
2. Original quilt
3. Coplanar vertices, translation is not allowed along the y-axis
The edges and vertices on the plane that passes through the origin of the CS3 coordinate system (the yz- and xz-planes, respectively) remain fixed. This is because translation is not allowed along the x- and y-axes.