A TIN surface comprises the triangles that form a triangulated irregular network.
TIN lines form the triangles that make up the surface triangulation. To create TIN lines, AutoCAD Civil 3D connects the surface points that are closest together. The elevation of any point in the surface is defined by interpolating
the elevations of the vertices of the triangles that the point lies in.
TIN surfaces are most useful for:
- Mapping highly variable surfaces with irregularly distributed sample data representing the influence of streams, roads, and
- Examining localized areas (large-scale maps)
TIN surfaces generally take longer to build and require more disk space than grid surfaces.
When AutoCAD Civil 3D creates a TIN surface from point data, it computes the Delaunay triangulation of the points. With Delaunay triangulation, no point lies inside the circle determined by the vertices of any triangle.
Breakline data (from breaklines, contours, or boundaries) influences how the surface is triangulated. A breakline edge between
the points causes the program to connect these points with a triangle edge in the TIN, even if doing so violates the Delaunay
A TIN surface with contour lines:
Tutorial Exercise: Creating a New TIN Surface
To create a TIN surface
In the Create Surface dialog box, in the list, select .
- Click to select a layer. For more information about layers, see Object Layer Dialog Box.
If you do not select a layer, the surface is placed on the current layer.
- In the properties grid, click the column for the property and enter a name for the surface.
To name the surface, click its default name and enter a new name, or use the . For more information, see Name Template Dialog Box.
- To change the style for the surface, click the property in the properties grid and click in the column.
The dialog box is displayed. For more information, see Surface Styles and Display.
- To change the render material for the surface, click the property in the properties grid and click in the column.
The dialog box is displayed. For more information, see Assigning Render Materials to Objects
- Click to create the surface.
The surface name is displayed under the collection in the tree. For information about adding data to the surface, see Adding and Editing Surface Data.
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