Deforming Elements According to
Shape Morphing

This command is only available with the Generative Shape Optimizer product.
This task shows how to deform elements based on shape morphing, that is matching each reference curve or point (reference elements) onto a target curve or point (target elements)
The deformation is then defined by the transformation of the reference curves or points into target curves or points.
The elements used for the deformation do not necessarily lie on the initial element.
  Several cases are presented here, from the simplest one to cases using various options. Note that whatever information is given in the first example also applies to the following examples.
Open the ShapeMorphing1.CATPart document.
 

Basic shape morphing deformation
 

  1. Click Shape Morphing .

    The Shape Morphing Deformation Definition dialog box is displayed.
     

  2. Select a curve in the 3D area and the selection automatically appears in the Element to deform  box.

  3. In the 3D area, successively select the first reference element and the first target element.

  4. Repeat this operation by selecting the second reference element then the second target element.

    As you select pairs of reference/target elements, the list in the Deformation Elements tab is updated accordingly.
     

  5. Click Preview to visualize the deformation.

    The previsualization shows that:
    • the deformation is applied to a group of points.
    • there is a constraints' mapping between the reference and the target curves.
    You can visualize the mapping constraint by selecting a number in the Constraint dialog box.

  6. Click OK to create the deformed element.

    The element (identified as Shape Morphing.xxx) is added to the specification tree.
    You can apply a constraint on the target element with the associated support element.
    The combo list displays the available continuity types depending on the reference/target elements you chose.

    • If you select a reference and a target element, the Point and the Tangent continuity are available.
      In the case of Point continuity, the Support field is grayed.

      In the case of Tangent continuity, select a support element so that the continuity is kept.

    • If you select only reference elements, all continuities (Point, Tangent, and Curvature) are available.
      In the case of Tangent or Curvature continuity, you do not need to select a support element as the element to deform is taken into account.

    • If you select the Type as Reference translation / Reference isometry / Reference similarity / Reference linear transformation, the None (G0), Rigid tangency and Rigid space constraints are available.
 

Deform an Element using Autocoupling modes
In case of reference and target wires consisting of many edges, you can set coupling points automatically by selecting an autocoupling mode for the reference-target pair selected in the Deformation Elements tab.
  1. In the work area, select a surface as Element to deform.
  2. Successively select the first Reference element and the first Target element, which appears in the Deformation Elements tab.
     
  3. Select Tangency in the Automatic coupling points combo box.

    All vertices located at G1 continuity breaks places are selected to be set as coupling points.
    This mode has only effect if

    • the deformation wires have G1 discontinuities,
    • reference and target have the same number of G1 discontinuities.

    If these conditions are not met, Tangency autocoupling mode has no effect or, if Vertices mode is also disabled, is not available.
  4. Select a second reference and target element.
     
  5. Select Vertices in the Automatic coupling points combo box.
    All manually selectable vertices are selected to be set as coupling points.
    This mode is only available if
    • the deformation wires have selectable vertices.
    • reference and target have the same number of vertices.
    If Vertices coupling mode is not available, Tangency mode is also disabled.
  6. Select a vertex from the second reference as Reference's origin and a vertex from the second target as Target's origin.
    In case of closed wires, the deformation wires' origins from where the definition of the pairs of coupling points will start, has to be selected manually.
    In case of open wires, their start point is automatically selected as origin.
  7. Click Preview to visualize the deformation.
  8. Select the first deformation elements line in the Deformation Elements tab.
    In the work area, the elements selected as first reference and target are highlighted and handles appear at the vertices.
    In the Shape Morphing Deformation Definition dialog box, the Reverse direction button is enabled.
  9. Click a handle or the Reverse direction button.

    The direction is reversed.
    In case of open reference and target wires the direction determines the start point on the wires from where the first pair of coupling points is defined. Reverse direction reverses start and end point of the wires and thus the direction of the pairs of points definition.
    In case of closed wires, Reverse direction reverses the direction in which the pairs of coupling points are defined beginning from the selected origin.
  10. Click again Preview to visualize the deformation.
     
  11. Click again a handle or Reverse direction button to undo the last step.
  12. Click OK to create the deformed element.
    The element (identified as Shape Morphing.xxx) is added to the tree.
     


 

Defining Limit Elements
  You can define one or more limit elements to separate a feature in multiple parts. You can then decide which parts of the feature you want to deform and which parts to keep intact (freeze).
Here is an example using Intersect1. as Limit curve and a Tangent Continuity.
The Reverse Direction button enables to deform the element on the other side of the limit curve. You can also click the arrow in the 3D geometry.
By default, the limit element has a point continuity and right direction.
 

 
 
 
 

Coupling Points
  Use this tab to define coupling points in order to map reference elements with target elements.
    Points must be located on reference and target curves.

In the Coupling Points tab, select the Reference point and its corresponding Target point.
 

  1. In the Manual Coupling Points tab, select the Reference point and its corresponding Target point.

  1. Click Add to select more coupling points or Remove button to remove the coupling points.
     

 
 

  • You must always select successively a reference then a target element to define a pair. You cannot select all reference elements, then all target elements for example.

  • When several pairs of curves are selected, they must be ordered, not randomly selected.
   
Reference and target curves can be multi-cells. Joined, blended, or matched curves, for example, can be used as reference or target curves.
  Rigid Zones
Sometimes you need to preserve some faces, shapes and dimensions without attenuating the deformation.
  1. Click Shape Morphing .
    The Shape Morphing Deformation Definition dialog box is displayed.
  2. Select the surface as the Element to deform.
    Rigid Zones functionality works only for deforming surfaces.
  3. Select the reference and target elements.
  4. In the Rigid Zones tab, select the faces from the surface to deform by any of the following ways:
    • Select faces from the 3D area.
    • Select faces previously extracted from the surface in the tree.
    • Select faces by creating extract features (Create Extract, Create Extract(in point), Create Extract(in tangency), Create Multiple Extract) by right-clicking the 3D area or the list in the Rigid Zones tab.

    You can remove and replace elements in the rigid zones list by selecting the rigid zone from the list and clicking Remove or Replace.
  5. Optional: Select elements from the list and click Distance Propagation to add to the list all the faces that can be reached from the selected zone according to point continuity propagation.
    Note: Depending on the part size and complexity, this action may take appropriate time.
  6. Optional: Select elements from the list and click Angular Propagation to add to the list all the faces that can be reached from the selected zone according to tangent continuity propagation.
    Note: Depending on the part size and complexity, this action may take appropriate time. 
  7. Optional: Click Preview to see the preview of the deformed surface.
    In the following examples you can see the preview of the deformed surface when rigid zones are not selected, when rigid zones are selected and when rigid zones are removed.
     

    When no rigid zones are set the preview appears in orange color.
    		  
    When rigid zones are set the feature is updated and no orange preview appears.    		  

    When all the rigid zones are removed, the previously computed result is seen in red color and the new result in orange color.
  8. In the Recognition context combo list, change the industry to Power Train.
    If faces set as rigid zones share fillets or chamfers with the surface to deform, in most cases the geometry is too complex to allow sewing the deformed surface to these rigid zones. In this case, the Shape Morphing Feature's result is not connex (i. e. it is multi-domain).
    If the fillets or chamfers are constant, the Recognition context combo list options allow sewing translated zones sharing fillets or chamfers with the surface to deform to this surface, provided the fillet's radius or chamfer's length belongs to the recognition context's range.
    The industries proposed have specific ranges, which are subject to change, in particular Ship Building's one:
    Industry Fillets' range Chamfers' range
    Power Train 0mm - 15mm 0mm-15mm
    BiW (Body in White) 1mm - 100mm 1mm-100mm
    Consumer Goods 0mm - 50mm 0mm-50mm
    Ship Building 0mm - infinity 0mm-infinity
    High Tech 0mm - 1.5mm 0mm-1.5mm
    Building 1mm - 100mm 1mm-100mm
    Machine Design 0mm - 15mm 0.03mm-1.5mm; angles range: 30deg-60deg
  9. Click Preview.
    The fillets' radius does not belong to Power Train's radii range, therefore, an Update Error dialog box opens.
  10. Click OK to close the dialog box.
    The translated zones which cannot be sewn to the deformed surface because they share smooth edges with the surface to deform are displayed in yellow.
  11. Change the recognition context to BiW.
  12. Click Preview again.
    The fillets' radius belongs to BiW's radii range. The surface is deformed and the rigid zones with shared smooth edges translated. The fillet between them is set back.
  13. Click OK to create the deformed surface.
    The Multi-Result Management dialog box appears if some rigid zones cannot be sewn to the deformed surface.
  14. Click OK.
    Note: Select keep all the sub-elements option to create Extract Features of the deformed surface and translated zones that could not be sewn to the deformed surface.
 

Use the Parameters Capability
  Use the Constraint propagation list to define the constraint propagation on the deformed surface to obtain the desired shape.
 
  In the Constraint propagation list, select the desired constraint propagation type.

The different constraint propagation are:

  • Low attenuation
  • Medium attenuation
  • Strong attenuation
  • Very strong attenuation.
    • The Strong attenuation and Very strong attenuation constraint propagations cannot maintain the Reference linear transformation continuity.
    • The magnitude of the deformation gets lower when the value of the constraint propagation is higher and thus large deformations are possible even with the Medium attenuation and Low attenuation options.
 

Deform a Surface with Limit Elements
  Sometimes, you need to create a deformed element in relation to another element. The shape morphing capability lets you fix an element that can be used by another one, thus allowing you to retain a connection between elements while deforming the initial element.

  1. Click Shape Morphing .

    The Shape Morphing Deformation Definition dialog box is displayed.

  1. Select the surface or the curve as the Element to deform.

  2. Select the first reference element.

  3. Select the target element.

  4. Click Add to add another reference element.

  5. Successively select the second reference element then the target element.

  6. Click OK to create the deformed element.
 

Deform a Wireframe with Limit Elements
  You can deform a wireframe with limit elements, provided they all lie on the wireframe’s support surface.

  1. Click Shape Morphing .

    The Shape Morphing Deformation Definition dialog box is displayed.

  1. Select the wireframe as the Element to deform.

  2. Select the first reference element.

  3. Select the target element.

  4. Click Add to add another reference element.

  5. Successively select the second reference element then the target element.

  6. Click the Limit Elements tab.

  7. Select one or more limit elements and adjust their continuity and direction as per requirement. Refer Define Limit Elements.

    All the limit elements should lie on the support surface that contains the wireframe.

  8. In the Support surface box, select the support surface.

    The Support Surface box is available only if you select a wireframe for deformation.

  9. Click OK to create the deformed element.
 

Diagnosis
  This capability lets you visualize the deviations in the 3D geometry when the result is not fully accurate.
The Warnings dialog box may also be displayed. Refer to the Managing Warnings chapter for further information.

  1. Click Shape Morphing .

    The Shape Morphing Deformation Definition dialog box is displayed.

  1. Select the surface or the curve as the Element to deform.

  2. Select the references, target elements, and Constraints.

  3. Click Preview to visualize the deviations:

    The Warnings dialog is also displayed. Refer to Managing Warnings for further information.

  4. Select a line in the dialog box to display the corresponding mapping and deviation.
    Here are the cases where warnings are displayed.
    • When inputs are of bad quality:

      • If the reference or target curves are not continuous.

      • If the reference or target curves are not continuous in tangency or in curvature and the discontinuities are not coupled.

    To solve the above warnings, we advise you to :

    1. Use the Curve Smooth command to smooth the small discontinuities, then

    2. Use the coupling point tab to associate the great tangency or curvature discontinuities between target and reference.
    • When reference curves intersect, there may be an incompatibility between constraints:
      • If the targets do not intersect
      • If the targets intersect but the mapping between reference and targets do not associate the reference's intersection with the targets' intersection. In this case, we advise you to add coupling points.
      • If the tangency constraint cannot be guaranteed.
  In the Knowledge Base
About selecting rigid zones