Description

The Patch command is used to easily create surfaces that patch holes in database geometry models using arbitrary intersecting sets of database curves and/or boundaries. More than one surface may be generated from a given set of database curves and/or boundaries. Database boundaries (u-min, u-max, v-min and v-max curves) are also created and are considered child entities to the new surface(s). Keep in mind that this command does not require a selection prior to being available; the desired database curves and/or boundaries bounding the new surface(s) can be selected within the command.

 

Tip: Patch surfaces are ideal for quickly filling gaps and holes in your database geometry.

In a nutshell, here is what you need to do in order to create a database surface using this command. Select the set of bounding database curves and/or boundaries from which you wish to create a new surface. Go to Create, Patch. Click on Generate Surfaces. Click on OK to save the new database surface(s) and close the panel or Cancel to save the new database surface(s) and remain with the panel open to generate additional surfaces.

Patch
Use the Patch command to repair geometry holes using sets of intersecting curves.

At the top of the Patch panel, you will find a table listing the number of database curves and/or boundaries selected, the number of pending Tangency Patches, Coons Patches, Trimmed Patches, and Trimmed Planes, as well as the number of Total Surfaces generated from the selected curves and/or boundaries.

  • Tangency Patches: Patch database surfaces which maintain local slope tangency with adjacent surfaces.
  • Coons Patches: The most generic type of patch database surface created by this command. This patch surface is created when no boundary tangency is applied (Tangency Patches), and when the selected bounding database curves and/or boundaries do not lie on an existent database surface (Trimmed Patches) nor on the same plane (Trimmed Planes).
  • Trimmed Patches: Patch database quilt created from an existent database surface or quilt. This type of patch surface is created when the selected bounding database curves and/or boundaries lie on the same existent database surface or quilt with extents larger than those of the selected boundaries. Note that a database surface or quilt can be used as a base to create this type of patch independently of its Layer and Show/Hide status.
  • Trimmed Planes: Patch database surface created from a database plane. This type of patch surface is created when the selected bounding database curves and/or boundaries are coplanar.

When creating a patch using this command, the software will present a preview of the new patch based on the selected bounding database curves/boundaries. Note that this preview will be colored-coded depending on the type of patch that will be created. This color-coding follows the same pattern used in the table a the top of the Patch panel.

Patch tangency Example
When creating a new patch, the software will render of a preview of the new patch color-coded based on its type following the pattern used in the table at the top of the Patch panel.

Immediately below the table, you will find the Boundary Tolerance frame. The Tolerance entry field inside this frame, allows you to change the tolerance from its default value of 0.001 when the set of curves is not producing a valid surface. Uncheck Use Default to enter a custom value in the provided entry field.

The Use Boundary Tangency checkbox enables the automatic slope tangency enforcement of the new patch at its boundaries. With the option checked on, the selected boundaries will be automatically evaluated to find an adjacent surface or group of surfaces that can be used to control the curvature of the new patch at its boundaries. The software will display a set of white arrows along the selected boundaries (see image above) to indicate which surface is providing the slope tangency enforcement at each boundary. When multiple surfaces are adjacent to a given selected boundary, use the space bar to toggle between the different surfaces. In the most general case, a new Tangency Patch will be created. However, if all the selected boundaries lie on a single underlying parent database surface or quilt with extents larger than those of the selected boundaries, a new database quilt will be created using the same parent surface (Trimmed Patch).

The Tangency Control Selection frame, provides tools to control which database surfaces and/or quilts can be used to enforce patch tangency. By default, all visible database surfaces and quilts can be used for this purpose. Use Begin to select specific database surfaces and/or quilts that can used to enforce tangency. Once the selection is complete, End to save and end the selection. On the other hand, use Cancel and Default to discard the current selection and to restore the default behavior respectively.

The Manual Side Definition frame provides tools to manually assemble edges of a surface providing more explicit control over the surface definition.

  • Remove Last Curve: Removes the previously added curve or boundary from the definition of the current surface side.
  • Remove All Curves: Removes all of the curves or boundaries from the definition of the current surface side.
  • Next Side: Saves the definition of the current side and moves on to the next.
  • Previous Side: Drops any definition of the current side and reverts control to the previous side in the surface. Use this command when you discover an error or omission in your previously defined side.
Manual Side Definition
Use the Manual Side Definition frame to explicitly define your surface edges.

Below the Manual Side Definition frame, the Generate Surfaces command creates the candidate database surface or surfaces from the selected set of database curves and/or boundaries along with the currently specified Tolerance.

Demonstration

Pointwise CAD Cleanup Series: How To Extend A Surface To Cover A Gap

Coons Patch Boundaries