INTRODUCTION AND DEFINITIONS
Break lines are lines or polylines that sub-divide the mesh; they represent the edges of a paved surface, a ridge, a channel, or any other topographic feature that the user wants to preserve. While mentioned in 2D topographic tracing, break lines become very important in meshing. Here, they have an accurate z-coordinate and they become the edges that the triangles in the mesh conform to, defining and controlling the smoothness and continuity of the mesh. They allow the user to break-up the mesh into reasonable “chunks” for future texturing and detailing.
Please see ‘Leica Cyclone – Creating a Basic CAD Ojects From Surface Topography (2D)’ as a supplement to this workflow.
OPEN A REGISTERED UNIFIED MODEL SPACE
SELECT AND DELETE UNNEEDED POINTS
CREATE NEW LAYERS FOR THE BREAKLINES AND FEATURES
3. Create new layers for the breaklines and features (Shift + L) -> Review the area to be modeled identifying where the surface changes and/or where the user wants a clean break or difference between adjacent surfaces.Create layers for primary and secondary features as needed.
4. Create lines to represent the topography and features, assigning an accurate x, y, and z coordinate -> There are several ways to make lines including (1) using 2D drawing methods (covered in ‘Topography and Site Elements – 2D’ above) (2) with pick points, (3) by extending an existing line (4) by snapping two existing lines together (5) by creating a polyline with Fit Edge command, and (6) by merging polylines together.
See Help -> Contents -> Search -> ‘Make Lines, Polylines, and Breaklines’ for steps for each of these methods.There are additional variations of each.BEWARE: Lines created by pick points cannot be used for break lines in meshing; if picking points, be sure to create a polyline rather than a line segment.
A. If drawn in 2D, use Edit Object -> Move/Rotate to move the object to the correct z-coordinate; there are multiple options moving objects including by a standard axis and pick points.
B. Create additional break lines following the feature or edge of the break lines; place these to break up the mesh and around the boundaries, segmenting out areas where a topographic ground plane is not needed (ie: inside buildings)
Figure 3 – Top view of plaza; Polylines have been created to outline where the sidewalk and grass meet; orange handles help highlight the polylines
C. Use multiple views to confirm line is properly located at all angles and handle constraints (Edit Object -> Handles constrain to -> Various options – NOTE: once placed in top view, constraining handles to z-direction helps placement in 3D)
D. Try different methods to see what works for you.With all, use multiple views to confirm the line is properly located at all angles
Figure 4 – (Left) Although from Top View, the breakline looks correct, inspection from a different angle reveals that it is not correct (Right) Handles and constraints (Edit Object -> Handles -> Constrain Motion) are used to pull the polyline into the correct position – every section of every breakline should be inspected from multiple views
7. Delete all points beyond boundary of mesh -> Select polyline representing boudary of mesh -> Right click -> Fence -> From Selection -> Fence -> Delete outside
8. Delete points within other breaklines to remove any remaining points that should not be considered in the creation of the mesh -> Copy final breaklines to original or temporary working space in case altered/needed in future
8. Unify points reducing spacing to 1 foot to start and adjust settings for desired results.
You are reading the series: Leica Cyclone - Creating a Mesh and Modeling Surface Topography (2.5D)
- Leica Cyclone – Creating a Mesh and Modeling Surface Topography: Setting Up the Model Space and Break Lines
- Leica Cyclone – Creating a Mesh and Modeling Surface Topography: Creating the Topographic Mesh