More about Wrapping

The following section aims at describing wrapping operation in more details:
 


How is the Wrapping Representation Calculated?Top

You generate a wrapping from existing geometric elements by:

  • computing a set of points regularly spaced on the envelope of the original geometry (distance between points = grain parameter)
  • offsetting these points to obtain a inflated result which better includes the original geometry (offset value = grain * offset ratio)
  • building triangles from the set of offset points.   

The following example aims at illustrating these three steps as well as the impact of grain and offset ratio parameters on the final result.
 

 

Step 1: Computing Points Using the Grain ParameterTop


Step 2: Offsetting Points Using the Offset Ratio ParameterTop

 

Step 3: Building the Result Top

Case 1: Offset Ratio = 0.0 
Case 2:  Offset Ratio = 0.5

Case 3: Illustration of how the frontier between inner area and outer area is calculated with a simplified envelope.


In this case, any geometry which is not visible from any of the six canonical directions is considered as internal and is not considered for the wrapping volume computation.
To take such geometries under consideration, use convex envelop.
Case 4: Cubic option set

When the cubic check box is selected, the result is a voxel (cubic) representation of the envelope. The voxel size equals the grain parameter. The offset ratio is not used.
 

Case 5: Illustration of how the frontier between inner area and outer area is calculated with a convex envelope.

The computation time is higher for the Convex envelop computation type, for the same grain size.
However, a higher grain size can be used because it ensures that the geometry is well contained in the envelope.

How the Grain and Offset Parameters Impact the Wrapping Calculation?Top

The table below shows the grain parameter impact on the wrapping calculation:

Grain Value
Computation Time
Used Memory
Resulting Size (number of triangles)
Greater Shorter Less Smaller
Smaller Longer More Bigger

The table below shows the offset ratio impact on the wrapping calculation:

Offset Ratio Value
Computation Time
Used Memory
Resulting Geometric Size
Resulting Size
(number of triangles)
Greater No Change No Change Bigger No change
Smaller No Change No Change Smaller No Change
Cubic Mode Shorter Less Includes entirely the original geometry No Change