Edge Edit Panel

Location: Geom page

Surface Edge Topology

Edge topology helps control the mesh generation for the surfaces and surface boundaries when using the surface automesher. Edges can have one of three states, each of which has a specific color in the rendering graphics.

Free (red): The surface edge is not connected to any other surface edge. The mesh generated across a free edge boundary will not be connected.
Shared (green): The boundary between connected surfaces (sometimes referred to as "stitched together").; The mesh across a shared edge will place nodes along the surface edge, and such nodes will be common to the elements on each side of the boundary. Shared edges are further classified as manifold (exactly two surfaces meeting at a common edge) or non-manifold (yellow), where more than two surfaces meet at a common edge. For the sake of simplicity, shared manifold edges are simply referred to as "shared" while shared non-manifold edges are referred to as "non-manifold".
Suppressed (blue): A manifold shared edge will be disregarded by the meshing process, in effect making a single larger surface out of two individual surfaces.

Topology Display

When entering any panel where the primary function is editing geometry, the surface topology display mode is activated by default. In this mode, the surface edges are colored according to their topology state. The default color assignments are red for free edges, green for shared edges, yellow for non-manifold edges and a blue dotted line for suppressed edges.

Subpanel Organization

You can move freely between subpanels. Your work on one subpanel will not be lost if you switch to a different subpanel. However, similar settings will not be shared between subpanels, so for example changing the cleanup tolerance in one subpanel does not change it in any of the others. In some cases, changes will be reflected immediately in your model as you select edges; in others, one or more green command buttons on the right edge of the subpanel can be used to execute the function once all criteria have been specified.

Toggle Subpanel

Use the Toggle subpanel to toggle edges from one state to another. The topology state can be advanced from free to shared to suppressed by clicking with the left mouse button. Conversely, the state can be regressed from suppressed to shared to free by using the right mouse button.

Exactly what state an edge takes on depends on its current state. Adjacent free edges can be advanced to shared edges with the left mouse button, provided the two edges are within the same space based on the cleanup tolerance setting. The tolerance is used to create a search sphere around the point that is clicked. If another free edge is found, it is considered for a pairing. Any paired edges are checked for an appropriate match along their length based on the cleanup tolerance. The shared edge resulting from this toggle operation will be at the location of the free edge that is clicked.

Left-clicking a shared edge will result in a suppressed edge. Left clicking a non-manifold edge has no effect, since the mesh must have nodes along such a boundary. Right-clicking a suppressed edge reverts that edge to the shared state. Right-clicking a shared edge releases the edge to the free state.

In general, left-clicking reduces the number of edges, while right-clicking increases the number of edges:

: Convert two free (red) edges to one shared (green) edge.; Convert a shared (green) edge to a suppressed (blue) edge.; Convert one free (red) edge and one shared (green or yellow) edge to a shared non-manifold (yellow) edge.
: Convert a suppressed (blue) edge to a shared (green) edge.; Convert a shared (green) edge to two free (red) edges.; Convert a shared non-manifold (yellow) edge to multiple free (red) edges.

Option	Action
at cursor: edge	Select an edge.
cleanup tol	Specify a value, in model units, above which separate edges will not be combined, toggled, replaced, or equivalenced. Edges that are this distance or less from each other will be altered as appropriate to the subpanel, while those further than this distance from each other will remain unchanged. Figure 1. Example: Cleanup Tol. With tolerance 0.1, the gap (size 0.625) remains. With tolerance 0.7, it closes as the selected edge is toggled to be shared with its nearest neighbor.

Option

Action

at cursor: edge

Select an edge.

cleanup tol

Specify a value, in model units, above which separate edges will not be combined, toggled, replaced, or equivalenced. Edges that are this distance or less from each other will be altered as appropriate to the subpanel, while those further than this distance from each other will remain unchanged.

(Un)Suppress Subpanel

Use the (Un)Suppress subpanel to suppress or unsuppress edges. Suppressed edges are treated as if they did not exist when meshed using the surface automesher, and their corresponding surfaces and resulting mesh will be continuous. However, the edges still remain in the database, and can be unsuppressed again if necessary.

Option	Action
lines selector	Select the surface edges to suppress or unsuppress.
break angle	Used to preserve geometric features within the selection; if the break angle between the normals of adjacent surface edges exceeds the set value, the edges will not be suppressed. For shared edges, this is the maximum tangential angle between two surfaces at the shared edge. Edges of surfaces exceeding this angle are not suppressed. Figure 2. Example: Break Angle. With a Break Angle of 0.1, some of the shared edges are suppressed (especially on the right side) but many remain.

Option

Action

lines selector

Select the surface edges to suppress or unsuppress.

break angle

Used to preserve geometric features within the selection; if the break angle between the normals of adjacent surface edges exceeds the set value, the edges will not be suppressed.

For shared edges, this is the maximum tangential angle between two surfaces at the shared edge. Edges of surfaces exceeding this angle are not suppressed.

Replace Subpanel

Use the Replace subpanel to move one edge line to the same edge as another, effectively combining the two edges into a shared edge at the location of one of the original edges.

This functionality provides additional control over the toggle function. Individual selections are made for the line to move and the line to retain. The resulting shared edge will be at the location of the line selected as retained.

The cleanup tolerance setting in this panel defines the maximum distance between the selected lines.

Option	Action
moved edge: lines selector	Select the surface edges to suppress or unsuppress.
retained edge: line selector	Select the edge line to move the other lines to.
cleanup tol	Specify a value, in model units, above which separate edges will not be combined, toggled, replaced, or equivalenced. Edges that are this distance or less from each other will be altered as appropriate to the subpanel, while those further than this distance from each other will remain unchanged. Figure 3. Example: Cleanup Tol. With tolerance 0.1, the gap (size 0.625) remains. With tolerance 0.7, it closes as the selected edge is toggled to be shared with its nearest neighbor.

Equivalence Subpanel

Use the Equivalence subpanel to search for free edges and combine them with a matching edge within the cleanup tolerance. The surfs selector allows selection of surfaces to check using any of the extended selection options.

Selected edges that meet other specified criteria will be equivalenced even if they belong to different components.

Option	Action
surfs selector	Select the surface to check.
geometry stitching	The surface stitching options define whether or not free-edge pairs are combined according to the following rules: by component Selected surfaces will be stitched to neighbor surfaces that belong to the same component. This is the default behavior. all Selected surfaces will be stitched to all neighboring surfaces, even if those surfaces belong to different components. attached to selection Selected surfaces will be stitched to surfaces attached to selected surfaces or edges. selection only Selected surfaces or edges will be stitched only to each other.
cleanup tol	The maximum distance between free surface edges for them to be considered a pair. Specify a value, in model units, above which separate edges will not be combined, toggled, replaced, or equivalenced. Edges that are this distance or less from each other will be altered as appropriate to the subpanel, while those further than this distance from each other will remain unchanged. Figure 5. Example: Cleanup Tol. With tolerance 0.1, the gap (size 0.625) remains. With tolerance 0.7, it closes as the selected edge is toggled to be shared with its nearest neighbor.
equiv free edges only	Restrict this operation to free surface edges only. Otherwise, a free edge that matches a shared edge can be combined to form a non-manifold edge. This option prevents shared edges from being equivalenced; only free edges will be equivalenced. Figure 6. Example: Equiv Free Edges Only. All surfaces are selected, but only the two free edges on the left are made equivalent with each other. The shared non-manifold edge on the right remains unchanged.

Unsplit Subpanel

Use the Unsplit subpanel to remove previously created split-lines; that is, lines that have been added to split one surface into multiple surfaces. This function can also be used to remove closed-edge loops, such as holes in a surface.

Note: The unsplit function removes any edge, either within a single surface or an edge between surfaces that both have the same underlying parent surface. It also tries to find a closed loop of edges to remove. This enables it to remove any closed loop or cutout feature, such as a hole or slot, contained within a surface.

Option	Action
at cursor: line selector	Select a single line to unsplit and carry out the operation immediately upon selection.
multiple edges: lines selector	Select multiple lines (with extended entity selection) and carry out the operation upon clicking untrim.

Edge Fillets Subpanel

Use the Edge Fillets panel to remove fillets from surface edges.

You can replace fillets in one of two ways:

The left side of the panel presents a search and select option to automatically identify surface edge fillets.
The right side presents a trim intersect option in which you manually remove the edge fillet by selecting the fillet endpoints.

Both options display on this subpanel, but are mutually exclusive: you may use one or the other, but you cannot use both on the same fillet. You can, of course, use both types in the same model, just not on the same fillet.

The option to remove fillets can be performed on as many fillets as you wish; all fillets in the model meeting the criteria you specify will be located and selected. Replacing a fillet with a trim-intersection corner, however, is a manual process that can only be performed on one fillet at a time.

The Search function requires selection of the surfaces to check for edge fillets. The minimum and maximum radius values bound the search to avoid looking for very small or very large fillets. The minimum angle sets a minimum arc length for a fillet to be identified.

Once surfaces have been selected and the search criteria entered, click find to identify any edge fillets meeting the search criteria. Fillets will be identified with the letter "F" at the arc center and radial lines indicating the beginning and end points on the surface edge. At this point, the fillets selector is active with all identified fillets pre-selected. Any fillets that you do not wish to remove may be de-selected by right-clicking them in the modeling window.

Click remove to extend the surface edges tangentially from the fillet end points until they meet at a hard corner.

The min radius, max radius and min angle options filter the fillets that will be converted into corners. Only fillets whose radius falls between the min/max values and have an arc of at least the min angle will be modified; all others will remain unchanged.

The trim-intersect function requires you to specify the two fillet end points. To use this function, activate the top node selector, then click the surface edge at the approximate location of one end of the fillet. A temporary node will be created, and the node selector will advance. Now, click the surface edge at the other end of the fillet. The surface edges will be extended tangentially from the points selected until they meet at a hard corner.

Option	Action
surfs selector	Select the surface to find.
fillets selector	Select the fillet to find.
min radius	Only fillets with a radius of at least this length will be found.
max radius	Only fillets with a radius of less than this length will be found.
min angle	Only fillets with an arc of at least this number of degrees will be found.
all / rounds / fillets	Choose whether to find fillets, rounds, or all. Fillets are typically quarter-circles or less, while rounds are quarter- to-half-circles. All searches for both types.
trim-intersect: node selector	Select one of the end points of the fillet you wish to remove by clicking the fillet's line in the modeling window.
trim-intersect: node selector (second)	Select the other end point of the fillet you wish to remove by clicking the fillet's line in the modeling window. A second temporary node is created, and the fillet is removed to be replaced by a corner. The corner is formed by extending the two lines on which the nodes you selected lie, until they touch.

By Feature Subpanel

Use the By Feature subpanel to combine surfaces based on geometric features. Edges meeting the criteria specified on this subpanel will be suppressed so that the corresponding surfaces are treated as being continuous by the meshing engine. Edges falling outside the criteria remain unmodified.

The angle surfs and offset surfs values preserve green edges between surfaces whose break angle (difference in surface normal direction) is more than the input value, ensuring that features are not suppressed. These normals are calculated and compared at an offset distance from their common shared edge. You can adjust both the angle and the offset distance.

Option	Action
surfs selector	Select the surface to modify.
close / leave orphan	Choose whether or not you wish the geometry engine to attempt to create closed loops from any non-closed features, such as an incomplete circle or u-shaped feature.
angle surfs	Preserve shared (green) edges between surfaces whose break angle (difference in surface normal direction) is more than the input value. These normals are calculated and compared at an offset distance from their common shared edge. You can adjust both the angle and the offset distance.
offset surfs	Specify the offset distance to be used in conjunction with the angle surfs value.
min fillet/max fillet	Preserve the shared (green) edges along the line of tangency of the surface fillet and its adjacent surfaces. The faces that comprise the length of the fillet are combined (their edges are suppressed). You can adjust the minimum and maximum fillet radii to be considered.
angle vertex	Check angle vertex to preserve the shared (green) edges leading away from a surface vertex whose exterior angle is greater than a user-specified angle. This option works on only suppressed edges and unsuppresses them where this criterion fails. Therefore, if you use move mode with this option alone it will not provide effective results. Figure 10. . The two suppressed (dotted) edges in the center-right of the model are unsuppressed (solid green) when using an angle vertex value of 220 degrees.
shape ratio	Check for surfaces that have shape ratio (ratio of the lengths of opposite edges) greater than the user-specified value. In such a case, any suppressed edges present inside that surface are unsuppressed to reduce the shape ratio. Similar to vertex angle tool, this option works effectively with update mode or in combination with other options. Figure 11. . The small suppressed edges near the circular hole are unsuppressed, making the surface ratio fall within the specified threshold.
min edge	Detect edges that are smaller than the user-specified value. The edges that are detected as small are fixed in three ways: If the small edge contains any fixed points that aren't required for geometric connectivity, those fixed points are suppressed. If the edge is much smaller than the minimum specified (less than 1/10th of specified value), the edge is degenerated (one of the end points is replaced by the other). In the remaining situations, edges are suppressed wherever possible to avoid small length edges. Figure 12.