Creating a Surface with Point Groups

Usually, existing surfaces are created from data collected from topographic surveys. From that data, a set of relevant surface points can be isolated by defining a point group. This point group is a quick means of adding point data to a surface definition. Point groups are covered in the discuss of “Points”.

In the exercise that follows, you’ll build your first basic surface with a point group:

1. Open the file 0401_SurfaceFromPointGroup.dwg or (0401_SurfaceFromPointGroup_METRIC.dwg).
2. On the Home tab of the ribbon ➢ Create Ground Data panel, select Surfaces ➢ Create Surface.
3. In the Create Surface dialog, shown in Figure 1, click in the Name field.

   Figure 1:  Creating your first new TIN surface.

4. Remove the default text by highlighting it and replacing it with the name Existing Surface.
5. Set Style to Contours 1’ and 5’ (Background) or Contours 0.5 m and 2.5 m (Background) for metric users and click OK.
6. In Prospector, expand the Surfaces branch. You should now see your new surface in the listing.
7. Expand Existing Surface and then expand Definition by clicking the tiny plus sign to the left of the listing in Prospector.
8. Right-click Point Groups and select Add.
9. In the Point Groups dialog, highlight TOPO Shots and click OK. You should now see contours for your surface.
10. Save your drawing at the conclusion of the exercise. Compare your work with 0401_SurfaceFromPointGroup_FINISHED.dwg or (0401_SurfaceFromPointGroup_METRIC_FINISHED.dwg) if desired..

===o0o===

Creating Surfaces

• Creating a Surface with Point Groups
• Adding Breaklines
• Breakline Types
• Weeding Factors
• Supplementing Factors
• Adding Boundaries