SurfacesObjectivesNotes to InstructorStudent ExercisesSurfacesKey TermsQuestionsAnswersModule SummaryNOTES Module 06 Surfaces In this module, students learn how to work with surfaces in Civil 3D 2008. Surfaces are three dimensional objects used to represent both existing and proposed terrain conditions. The display of a surface is controlled with a surface style. Surfaces can be displayed with different components including contours, triangles and points. Surfaces can also be annotated with contour elevations, spot elevations and slopes. Engineers usually display existing terrain surfaces on their plans with contours. During the design process engineers regularly work with existing terrain surfaces. These are used to check the interaction between the proposed design and the existing terrain. Engineers also create surfaces representing proposed conditions during the design process. These surfaces are used to help visualize the design, calculated material quantities and to generate data required for construction staking. Objectives After completing this module, students will be able to: Describe how surfaces are used in the site development process Create surface styles to control surface display Set the default style and naming template for surfaces Create a surface using points and breaklines Modify the surface properties Edit a surface Assign a contour style to a surface and apply surface labels Export a surface to Google Earth Import an image from Google Earth Drape an image on a surface and use the object viewer.AutoCAD Civil 3D 2008 Education Curriculum NOTES Notes to Instructor Data for this module resides in the \AutoCAD Civil 3D 2008 Education Curriculum\Module 06 - Surfaces\ folder. Students will also require Google Earth and a live internet connection for the last few exercises in this lesson. Student Exercises The following exercises are provided in step-by-step format. Open the Civil 3D program prior to beginning the lesson by double clicking on the Civil 3D icon on the desktop. Students working in the Imperial system should use the drawing files beginning with an I, while those working in the metric system should use the drawing files beginning with an M. Students are provided with a drawing for each exercise in the lesson. The exercises in this module are as follows: 1. Create surface styles 2. Set default surface style and naming template 3. Create a surface 4. Modify the surface properties 5. Edit a surface 6. Assign a contour style and apply surface labels 7. Export a surface to Google Earth 8. Import an image from Google Earth 9. Drape an image on a surface 06-2Module 06 - Surfaces NOTES Surfaces Surfaces play a very important role in civil engineering and site development projects. Surfaces are used to represent the three-dimensional nature of the existing topography and the proposed design. There are many ways to represent surfaces in a CAD environment. Civil 3D uses a TIN (Triangulated Irregular Network) to represent a surface. A TIN is usually created from points, breaklines and contour data. In this Module, students create surfaces from points and breaklines. TIN surfaces are created by connecting points with lines until no further connections can be made. The following illustration shows an example of a TIN surface model. The lines you see represent 3D lines that connect the points. These lines form the topography of the surface and it is important that they are positioned correctly. Breaklines represent distinctive breaks in the terrain. Examples of breakline include road crowns, top of bank, bottom of bank, ditch edges, stream edges, gutter lines and retaining walls. It is important that triangulation lines run along breaklines. The following illustration shows an incorrect TIN model because breaklines have not been defined. 06-3AutoCAD Civil 3D 2008 Education Curriculum NOTES In the previous illustration, notice that the triangulation lines do not run along, but pass over sidewalks, pavement edges and road crowns. This means that the surface is not accurate. After defining these features as breaklines in Civil 3D, the TIN appears as follows: Notice that the triangulation lines now run directly over the breaks in the terrain such as sidewalks and road crowns. This is an accurate surface model. Surface styles are used to control the display of the surface. Surface styles can be used to show the surface as triangles, contours, grids, points and borders. Once a surface has been created, you can assign a surface style to change the display of the surface. Engineers typically use surface styles that display triangles when creating surfaces and surface styles that display contours when creating engineering drawings. Once the surface has been created you can label spot elevations, slopes and contours. You can also export data to and from Google Earth. This is discussed in the last few exercises of this module. 06-4Module 06 - Surfaces NOTES Key Terms DTM Digital Terrain Model. A digital terrain model is another name for a surface. TIN Triangulated Irregular Network. AutoCAD Civil 3D uses a TIN to represent surface models. A TIN is created by connecting point with closest proximity. Breakline Breaklines represent distinct terrain breaks. Examples of breaklines include road crowns, gutters, top of bank, bottom of bank, ditch edges, stream edges and sidewalk edges. When creating surfaces, breaklines must be defined. Triangulation lines are forced to “break” the terrain and run over the length of defined breaklines. Triangulation lines can not cross over breaklines. Proximity Breakline A proximity breakline is defined from 2D polylines. Proximity breaklines assign vertex elevations by physically relocating them to the nearest surface point. 2D polylines created with vertices at the point nodes do not relocate. Contour A contour line connects points on the surface with constant elevation. Contour lines are created by connecting locations on triangulation lines with the same elevation. Surface Style The surface style controls the display of the surface. Surface styles can be used to display surfaces as triangles, points, contours, borders or grids. You can also create surface styles to suppress the display of a surface. This is especially useful when working with large surfaces. Naming Template Naming
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