Create and Edit a Simple Breakline
Simple breaklines are simplified linestrings that help to define the shape of a surface as do other 3D line types that act as breaklines, by controlling how triangles in the surface mesh are formed. Triangles forming a surface never cross a breakline. Use breaklines of any type to more accurately reflect where surface topography changes.
Often, you will create a breakline by adding linestring segments between points where surface triangles converge (at vertices), but you can also add simple breakline segments freely between any two locations on or near the surface. The addition, deletion, or any edit to a 3D line serving as a surface breakline will cause the entire surface to be reformed. Unlike more complex linestrings, simple breaklines do not use vertical control points; you can enter elevations for each new vertex or derive elevations from existing vertices.
To create a simple breakline:
- Do one of the following:
- Select Create Breakline in Surfaces > Create.
- Right-click a surface, and select Create Breakline from the context menu.
The Create Breakline command pane displays.
- In the Name box, type an identifier for the linestring as you want it to appear in the Selection Explorer and in graphic views when you select from multiple objects. You can also use the name to select the linestring in the Advanced Select command.
- Select a layer on which to create the linestring in the Layer list, or select <<New Layer>> to create a new layer for the linestring.
- Select an option for how smoothly the surface is rendered at this particular linestring in the Surface sharpness list.
- Select the surface to which the linestring will be assigned as a member in the Add to surface list.
- Click . The Edit Linestring command pane displays with reduced options appropriate for creating a simple breakline.
- In the Start Point group's Type list, select Coordinate to start the linestring at any location, or select Point ID to attach the linestring to a named point.
- Click in either the Coordinate box or Point ID box (depending on what you chose for the starting point type), and use one of these ways to specify each point along the linestring:
- In a graphic view, pick a vertex on the surface, or pick a named point (which may be a member of the surface and therefore one of its vertices)
- Pick any location on or near the surface in the graphic view, and then type an elevation in the Elevation box. Then, click Save or press .
- Type a coordinate, press , and type an elevation in the Elevation box. Click or press .
The first point of the simple breakline is saved and you are prompted to add the second point and specify how the segment between them is formed.
Note: To use the elevation from a point you pick anywhere on a surface, right-click and select From Surface Snap from the context menu. You are prompted to pick the point in the From Surface Snap command pane. Then, click Save or press .
Note: To avoid picking points off of the surface (with no elevation), uncheck the Free snap in the Snap Mode dialog when you create a simple breakline or linestring. If you are prompted for an elevation, you may have missed the vertex point you were trying to pick.
Note: You can also draw a 'freehand' breakline without using any existing data. In fact, you do not even need to have a surface to create a breakline. - Keep adding segments to the linestring using one of the methods in step 8.
- Click . The simple breakline appears on the surface in graphic views, but does not appear in the Project Explorer.
Note: Once created, linestrings can be graphically selected and added to other surfaces.
Tip: To view changes to your surface more clearly as you work, open a 3D view and move it to a new tab group next to your plan view so you can see both views concurrently.
To edit a simple breakline:
- Use the operations in Edit a Linestring's Horizontal Segments.
