Overview: In BricsCAD, topographical surfaces are created using the TIN Surface (triangulated irregular network) tool.
- Points contain x, y coordinates, and z values. All points are used to make a connection with the two nearest neighbours to create triangles. The surface triangulation is based on the Delaunay algorithm, which ensures that no point is inside the circumcircle of any triangle.
- Breaklines represent linear infrastructure features like curbs, retaining walls, etc. These lines also define the edges of triangles. Breaklines can be created from linear entities such as line, polyline, arc, circle.
- Boundaries are the features to define bounded 3D surfaces. The surface boundaries can be created with closed polylines. Defining outer boundaries in a large 3D surface improve the performance of a TIN Surface plan.
Lesson objectives: After completing this lesson, you will be able to:
- Create toposurfaces from a selection set of points and polylines.
- Importing points file, such as survey points data obtained from a surveyor. These points can be used to create a topographical surface.
- Creating a topographical surface by placing Points in the drawing area set by elevation.
- Add the linear entities as breaklines or points to the TIN Surface.
- Create toposurface from Civil 3D surface.
Tutorial: How to create a TIN Surface
Click here to watch
Creating a TIN Surface is a process that needs to be followed to map a particular area in detail. On BIM models, these topographic surfaces are used to represent the site. The topographical surface can be generated based on drawing entities, data imported from a comma delimited file format (CSV) or text file format (TXT), and points placed at different elevations, created from Civil 3D surface.
For more information about this command, visit the Command Reference article Tin.
Setting the TIN Surface preferences
- Open the Settings dialog.
- Under Civil options, expand the TIN Surface settings category.
|Arc approximation mid-ordinate distance||
Mid-ordinate distance is the maximal distance between arc and chord (straight) segment which is used for arc approximation.
Defines how many points along the curve you want to add. When you have polylines with curves, this parameter allows you to tessellate the arcs in the polyline. The default value of this parameter is variable in Bricsys predefined templates. For instance, the distance value is set to 0.01 in BIM-m, 1 in BIM-cm, 10 in BIM-mm, and 0.4 in BIM imperial templates.
|Allow breakline crossings||
Defines if crossing breaklines are allowed. By default, it is set to "On".
If breakline crossings are allowed, intersections between breakline segments are calculated and added as points to the TIN Surface.
|Elevation at breakline crossings||
Defines how elevation at crossing breaklines should be determined. There are three options (e.g., minimal, maximal, and average) for defining breaklines elevation at the intersection.
|Sampling interval for straight segments||
Defines the length of sampling interval which is used for sampling of straight segments (e.g. contour lines).
|Angle sampling interval||Defines angle sampling interval in decimal degrees, which is used for grading rounding at convex vertices.|
Enable/disable grading and surface associativities.
By default, the system variable is set to 3.
Procedure: Creating a Toposurface from a selection set of points and polylines
Open the drawing file that contains a set of points (1) and polylines (2).
- Launch the TIN command in the command line
Or select Create TIN Surface in the Model tab from the Quad.
You are prompted: Select entities to create TIN surface or [Import from file/Place points/Create from civil 3d surface]:
- Select the entities in the drawing area to create a toposurface.
Optional prompt menu can be used to select all entities (3) in the drawing area.
Command line depicts how many entities are included in the set, e.g. Entities in set: 2044.
- Press Enter.
The toposurface (4) is created from selected entities. Points are added to surface as points, 3D polylines are added to surface as breaklines.
Procedure: Creating a Toposurface from an imported points file
- Launch the TIN command in the command line. Or select Create TIN Surface in the Model tab from the Quad. You are prompted: Select entities to create TIN surface or [Import from file/Place points]
Select the Import from file (5) option in the prompt menu. Or type "I" in the command line. Open points file (6) dialog box displays:
Choose the point data file you want to open.
Click Open to import the points. The toposurface (7) is imported from an existing survey points file.
Note: If the toposurface is not shown in the current viewport, use the Zoom Extents option to display it to the extents of entities.
Procedure: Creating a Toposurface by placing points:
- Open a new drawing.
Note: The new drawing starts with the default template as defined by the BaseFile system variable.
- Launch the TIN command in the command line.
Or select Create TIN Surface in the Model tab from the Quad.
You are prompted: Select entities to create TIN surface or [Import from file/Place points]
- Select the Place points (8) option in the prompt menu.
Or type "P" in the command line.
You are prompted: Pick point
- Pick a point where you want to start creating the toposurface.
You are prompted: Enter elevation <0.000>
- Specify the elevation value of each those points, and press Enter to accept.
Note:At least three points are needed to create a TIN Surface.
Procedure: Creating a TIN surface from a Civil 3D surface
- Open a drawing with a Civil 3D surface
- Launch the TIN Surface command.
- Select Create from civil 3D surface.
You are prompted: Select a Civil 3D surface.
- Select the Civil 3D surface.
A TIN Surface is made.
Displaying the properties of a TIN surface
- Select the TIN Surface.
- The properties of the TIN Surface are displayed in the Properties panel:
|TIN Visual Style (9)||
Controls the visibility of the following properties:
To turn one of the properties on/off, click their field in the Properties bar, then press the arrow button and choose On/Off in the context menu.
|TIN Settings (10)||
Controls the contour lines settings.
|TIN Statistics (11)||
Demonstrates the statistical information about the TIN Surface.