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Modify subdivision creases

Use the Modify Subdiv Crease tool to edit creases in your subdivision objects including creases that were created in other applications such as Autodesk Maya or Autodesk Fusion 360. Using this tool you can:

  • Modify the fade between creased and non-creased topology to create smooth transitions.
  • Adjust the default sharpness of a crease by softening or exaggerating it.
  • Offset the position of a crease to either side of the edge center point.

About modifying creases

Before modifying creased edges, note the following:

  • Crease modifications made by the tool are only supported by Alias subdivision objects. Edits, such as the crease fades, applied to subdivision objects in Alias do not persist when the subdivision object is exported to other applications such as Autodesk Maya and Autodesk Fusion 360.
  • Modifying a crease changes the underlying limit surface of the subdivision object. This means that the crease modifications have construction history, which is indicated by the green wireframe. The subdivision control cage is not affected by the tool.
  • Since crease modifications change the subdivision limit surfaces, these modifications persist when opened in applications that support Alias surfaces.

Guidelines for modifying crease fades

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After selecting a creased edge, Alias display areas in red when the subdivision topology does not support a crease fade. This can happen in the following situations:

  • The crease starts at a boundary. To add a crease transition, uncrease one or more edges at either end.
  • Two or more adjacent creased edges are not available to create the transition.
  • The selected crease intersects with another creased edge.
  • There is less than two edges between the end of the crease and a sharp curve along the edge.
  • The creased edge is adjacent to a face with more than four edges, which is also known as an n-sided polygon.

Modify fades between creased and uncreased areas

  1. In the Subdivision tool palette, select the Modify Subdiv Crease tool: .

  2. Select the crease fade you want to modify.

    The crease is now highlighted in green, and a default crease transition is applied to the selected crease. When you deselect the creased edge, it displays as a dashed line, which indicates that it has been modified. The surrounding topology wireframe displays green, indicatiing that it now has construction history.

  3. To choose another transition Length, in the viewport, do any of the following:

  • RMB-click under Length and select a value from the list.

  • LMB-click under Length to cycle through the Length values.

  • Click a point along the edge where you want the crease transition to end.

Remove the crease transition

  • In the viewport, right-click under Length and select Off or click the first edge in the transition. When you turn off a crease transition, the subdivision control cage is not modified. Only the underlying surface is modified, which has history and can be query edited and turned on again.

    Note:

    To delete the transition, delete the Modify Crease tool construction history. After deleting, the creased data is no longer part of the subdivision limit surface. The data can be retrieved as templated surfaces with each surface appearing in the Object Lister as individual nodes.

Adjust the sharpness of a crease or offset the crease position

There are some scenarios when the Sharpness and Bias parameters cannot be modified. These include the following:

  • There is a curve along the creased edges.
  • A CV along the crease is not connected to quad topology. For example, a CV along the crease is a valence 5 vertex or higher, which is also known as a star-point.
  • A crease fade is set to Off at either end of the creased edge.
  1. In the Subdivision tool palette, select the Modify Subdiv Crease tool icon , then click the icon to open the control window.

  2. Select the crease you want to modify and do the following:

    • To soften or sharpen the crease, adjust the Sharpness value. By default, subdivision creases have a Sharpness value of 1.
    • To offset the crease position, adjust Bias.

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