SMS:Process Boundary Triangles

File:SMS Process Boundary Triangles.jpg

Process Boundary Triangles dialog

When scatter points are triangulated, the resulting convex hull often contains triangles outside the desired mesh boundary. The Process Boundary Triangles dialog was developed to help remove invalid boundary triangles. To open the Process Boundary Triangles dialog:

• In the Scatter Module, make the Select Triangle tool File:SelectMeshElement.gif active
• Select Process Boundary Triangles... from the mouse right-click menu

OR

• In the Scatter Module, select Process Boundary Triangles... from the Triangles menu

Removal Options

• Aspect Ratio – A small aspect ratio (sometimes called edge ratio) will result in the removal of more triangles than a large edge ratio. Specifying too small of an aspect ratio will result in the removal of valid triangles. The aspect ratio is calculated by dividing the length of the triangle edge on the boundary by the length of the smallest triangle edge connected to the scatter vertex end points of the triangle edge on the boundary.
• Select – Triangles meeting the specified aspect ratio are selected when OK is pressed
• Delete – Triangles meeting the specified aspect ratio are deleted when OK is pressed
• Preview – Preview which triangles will be processed based on the specified aspect ratio

Using the Tool / Practical Notes

• Areas on the interior of the triangulation, such as islands, should be manually "seeded" by deleting one of the unneeded triangles in the interior region.
• Triangles will not be removed if their removal would result in:

• the removal of a scatter vertex from the triangulation
• the creation of a "bow tie" in the scatter set. A bow tie, a point in the scatter set where the scatter set is "pinched" to a single point, is shown in the image below.

"Bow tie" in a scatter set.

Related Topics

• Select Thin Triangles