The Advanced panel presents additional advanced parameters to control the characteristics of the surface mesh to be created, including controls to enable/disable 2D T-Rex for specific boundary types.

Create, Automatic Surface Mesh, Advanced tab
The Advanced panel provides additional, more advanced controls over the characteristics of the surface mesh being created.


The Parameters frame provides several additional parameters to control the characteristics of the resulting surface mesh. Parameters Frame
The Parameters frame provides additional parameters for identifying hard edges and mappable surfaces, refining the surface mesh, and determining which boundaries are considered for domain adaption.

The Edge Assembly Angle parameter is the angle (prescribed in degrees) used to determine whether or not to join connectors when generating the surface mesh. This parameter has a default value of 40.0 and a valid range of [0, 180).


Note: Changing the Edge Assembly Angle may affect how boundaries are reported on the Global tab. For example, if the new value for Edge Assembly Angle causes the smallest boundary edge to be joined when connectors are built, Min. Boundary Length in the Geometry Characteristics frame on the Global tab is updated accordingly.

The Hard Edge Angle parameter is the angle (prescribed in degrees) used to determine whether the edge between two quilts represents a convex or concave edge. This parameter has a default value of 45.0 and a valid range of [0, 180). If the angle between the quilt normals is greater than the prescribed value, the edge is classified as Convex (if the normals point away from the boundary) or Concave (if the normals point toward the boundary).

The Refinement Factor parameter is used to globally refine or coarsen the surface mesh. This parameter has a default value of 1.0 and a valid range of [0.125, 8].


Tip: The Refinement Factor can be used to quickly generate surface meshes for an entire mesh family. Once you are satisfied with the quality of the surface mesh, use factors < 1 to generate coarser surface meshes and factors > 1 to generate finer surface meshes.

The Mapped Subdivision Ratio parameter is used to identify thin surfaces for special mapped mesh handling (i.e. surfaces for which the unstructured domain should be mapped to an underlying structured domain). This parameter has a default value of 10.0 and a valid range of [0, ∞), where a value of 0 disables thin surface meshing.

The Mapped Subdivision Ratio parameter is used to identify surfaces that are good candidates for using mapped unstructured domains. The images show the difference between using a mapped domain (left) and an unmapped domain (right) for the blunt trailing edge of a wing.

The Mapped Subdivision Ratio parameter is defined as the ratio of the subdivisions of the long and short connectors for unstructured domains defined by four connectors. If the computed ratio is greater than the defined value, the connector distributions and dimensions are synced to create a balanced structured domain. The structured domain is then diagonalized with the Link option enabled using either the Best Fit or Keep Quads diagonalization methods, depending on the Algorithm setting on the Global tab. For more information on domain diagonalization, please review the description of the Diagonalize command in this User Manual.

After the Create Surface Mesh command is finished, hovering the mouse over the domains displays information about whether or not the domain is mapped in the probe area of the Status Bar. Domains that are mapped also display the computed subdivision ratio while domains that are unmapped show information about why it was classified as such. Please click the Mapped Domain Probe Messages button below to view a table showing the possible probe messages that could be displayed as well as their meanings. AltText

When you hover over domains while in the Automatic Surface Mesh command, the probe area of the status bar (red rectangle) displays information about whether or not that domain is mapped. This image shows a selection of the more common messages. Click on the Mapped Domain Probe Messages button below to see a complete list of all messages.

Message Meaning
Too many edges. The definition of the unstructured domain has more than 1 edge.
Not 4 connectors. The domain is not defined by exactly 4 connectors.
Wrong grid topology. A node or connector was used an incorrect number of times in the definition of the domain. Mapped domains expect each node to be used exactly twice and each connector to be used exactly once.
Not 4 nodes. The loop of connectors defining the domain does not contain exactly 4 nodes.
Invalid grid. At least one of the connectors is undimensioned.
Failed high-low test. The connectors in a mapped domain are expected to alternate their numbers of subdivisions: high-low-high-low.
Long sides not convex. At least one high subdivision connector is not classified as convex.
Subdivision ratio The ratio between the low subdivision count and the high subdivision count did not meet the specified limit.
Side ratio The ratio between a short side connector's current dimension and the target dimension (for a balanced structured domain) is too great.
Subdivision: Length ratio The length ratio is too high. The length ratio is computed as a ratio of two ratios: the subdivision ratio and the ratio between the average lengths of the short and long sides.
Span varies too much. The linear distance between sampled points along the high subdivision connectors varies too much from the length of the short side connectors.
Quilt has zero area. The computed quilt area is below the tolerance.
Failed area ratio test. The ratio between the expected area and the computed quilt area is too great. The expected area is calculated by subdividing the long sides into segments, connecting the ends of corresponding segments, and summing the quadrilateral areas.
Corner angle too large. A quad in one of the corners would have an included angle exceeding the specified target limit. This message is only possible when the Algorithm is set to Quad Dominant.
Invalid mapping. The structured domain was unbalanced.

The Boundary Proximity Influence parameter controls which connectors become sources for domain adaption and has three options:

  • By Orientation: Only connectors on the outward side of a domain's quilt are used as sources for domain adaption. This option is useful for preventing undesired clustering from connectors on the opposite side of the model and is the default option.
  • All: All nearby connectors are used as sources for domain adaption.
  • None: No connectors are used as sources for domain adaption.
The Boundary Proximity Influence determines which connectors (if any) influence clustering on the interior of domains. Use the By Orientation option (shown left) to prevent undesired bleed-through clustering that can sometimes result from using the All option (shown right).


The table in the Stretching frame provides controls for viewing, enabling/disabling, and refining the three different classified boundary types: Curvature, Convex, and Concave. Edges are classified as Curvature edges if the target connector dimension based on surface curvature is much greater than the target dimension based on the curvature of the edge's underlying curve definition (i.e. the edge is straight but the quilts sharing that edge have significant curvature in the direction normal to the edge). Connectors created on edges classified as Curvature are automatically assigned to an Angle T-Rex boundary condition.

Edges are classified as Convex and Concave according to the Hard Edge Angle parameter in the Parameters frame above. Connectors created on edges classified as Convex and Concave are automatically assigned to a Max. Aspect Ratio T-Rex boundary condition. For more information on 2D T-Rex boundary conditions, please review the 2D T-Rex Boundary Conditions page in this User Manual.

Stretching Frame
The Stretching frame provides tools that allow you to visualize, enable/disable, and adjust the refinement of the three types of classified boundaries.

The Type and # columns display read-only values showing the name of the classified boundary type and the number of connectors associated with that type, respectively. Use the Show column to enable/disable the display of each classified type. By default, the checkboxes are checked on and the connectors are rendered in the Display window using the corresponding color in the Show column. Uncheck the checkbox to disable the display of a classified boundary type.

The State column allows you to specify whether 2D T-Rex is enabled/disabled for a particular classified boundary type during the creation of the surface mesh. By default, Curvature and Convex are turned On and Concave is turned Off. Click in the State field of a row to bring up a drop-down menu that can be used to toggle the State On or Off.

The Scale Max. Edge column allows you to scale the edge length for a classified boundary type with respect to the settings on both the Global and Local tabs. Scale Max. Edge has a valid range of [0, 1] and the default settings are 1.0 if the State of the boundary type is On and 0.5 if Off.