Create a TIN Surface

Commands

TIN, TINASSIGNIMAGE, TINPROJECT

Overview

In BricsCAD, topographical surfaces are created using the TIN Surface tool (triangulated irregular network) or the TIN command.

A TIN surface uses two types of entry data: points and breaklines (polylines).

  • Points contain X, Y coordinates and Z values. All points are used to make a connection with the two nearest neighbors 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 or circle.
  • Boundaries are the features to define bounded 3D surfaces. The surface boundaries can be created with closed polylines. Defining outer boundaries on a large 3D surface improves the performance of a TIN Surface plan.

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.

Setting the TIN Surface preferences

Arc approximation mid-ordinate distance
Note: 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 BricsCAD predefined templates. For instance, the distance value is set to 0.01 in BIM-m, 1 in BIM-cm, 10 inBIM-mm, and 0.4 in BIM imperial templates.

Allow breakline crossings

Defines if crossings 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.
Associativity

Enable/disable grading, surface and corridor associativities.

By default, the system variable is set to 15.

0: Neither TIN surface, grading nor corridor associativity is enabled.

1: Enables TIN surface associativity.

2: Enables grading associativity.

3: Both TIN surface and grading associativities are enabled.

4: Enables TIN volume surface associativity.

5: Both TIN surface and TIN volume surface associativities are enabled.

6: Both grading and TIN volume surface associativities are enabled.

7: TIN Surface, Grading and TIN volume surface associativities are enabled.

8: Enables corridor associativity.

9: Both TIN surface and corridor associativities are enabled.

10: Both grading and corridor associativities are enabled.

11: TIN surface, grading and corridor associativities are enabled.

12: Both TIN volume surface and corridor associativities are enabled.

13: TIN surface, TIN volume surface and corridor associativities are enabled.

14: Grading, TIN volume surface and corridor associativities are enabled.

15: All TIN surface, grading, TIN volume surface and corridor associativities are enabled.

Properties of a TIN Surface

TIN Visibility
Boundary line

Change boundary line visibility.

Points

Change points visibility.

Triangles

Represents how the elevation points are connected to each other. It follows the Delaunay triangulation method where breaklines are not included in densification.

Contours

Represents the joining of points of equal elevation within a line.

TIN Contours
Major contours interval

Sets the major contours interval.

Minor contours interval

Sets the minor contours interval.

Major contours color

Defines the color of the major contour.

Minor contours color

Defines the color of the minor contour.

TIN Statistics
The number of points

Displays the number of points that define the TIN surface.

The number of triangles

Displays the number of non-overlapping triangles in the TIN surface.

Minimum elevation

Displays the minimum elevation value found in the TIN surface.

Maximum elevation

Displays the maximum elevation value found in the TIN surface.

2D area

Displays the 2D area calculated from the flat TIN surface.

3D area

Displays the 3D area that is calculated from the TIN surface.

Procedure: Creating a TIN Surface from a selection set of points and polylines

  1. Open the drawing file that contains a set of points and polylines.
  2. Launch the TIN command.
  3. Select the entities in the drawing area to create a toposurface.
  4. Press ENTER.
The toposurface is created from selected entities. Points are added to the surface as points, 3D polylines are added to the surface as breaklines.

Procedure: Creating a TIN Surface from an imported points file (.txt or .csv)

  1. Launch the TIN command.
  2. Select Import from file in the Command line.
  3. Choose the point data file you want to open or choose multiple files to import all at once.
  4. Click Open to import the toposurface.
Note: If the toposurface is not shown in the current viewport, use zoom extents to display it to the extents of the entities.

Procedure: Creating a TIN Surface of a selected area using Clip polygon

  1. Open the drawing file that contains closed polyline.
  2. Launch the TIN command.
  3. Select the cLip polygon option in the Command line.
  4. Select the closed polyline to use.
  5. Specify if the crossed breaklines should be removed.
    Note: If the surface we are going to make contains breaklines, we define what should happen to the breaklines crossing the clipped polygon.
  6. Select any of the options, Import from file, Create from Faces, Create from civil 3D surface.
    Note: Clip polygon works as a projection on the TIN surface. The TIN surface is created only in the area defined by the clip polygon.

Procedure: Creating a TIN Surface by placing points

  1. Open a drawing.
  2. Launch the TIN command.
  3. Select the place Points option in the Command line.
  4. Pick a point where you want to start creating a TIN surface.
    Specify the elevation value of each of those points, then press ENTER to accept.
    Note: At least three points are needed to create a TIN surface.

Procedure: Creating a TIN Surface from Faces

  1. Open a drawing file that contains 3D faces.
  2. Launch the TIN command.
  3. Select the create from Faces option in the Command line.
  4. Select desired 3D faces.
  5. Press Enter.

Procedure: Creating a TIN Surface from a Point Cloud

  1. Open the drawing file that contains a point cloud.
  2. Launch the TIN command.
  3. Select the point cloud in the drawing area to create a toposurface.
  4. Press ENTER. The toposurface is created from the point cloud.

Procedure: Creating a TIN Surface from a Civil 3D surface

  1. Open a drawing with a Civil 3D surface.
  2. Launch the TIN command.
  3. Select Create from civil3d surface.
  4. Select the Civil 3D surface. A TIN surface is created.

About TIN Assign Image

  1. Open the drawing file that contains a TIN surface and an image.
  2. Launch the TINASSIGNIMAGE command.
  3. Select the TIN surface.
  4. Select the raster image.
    Note: If the image is not shown on the TIN surface, change the Visual Style to Modeling or Realistic and set TIN surface triangles to ON.

About TIN Project

  1. Open the drawing file that contains the TIN surface and the entities (points, blocks, text, lines, polylines, circles…).
  2. Launch the TINPROJECT command.
  3. Select the entities to project.
  4. Select if the original entities are to be erased.