Trimming a Surface

Step-by-step:

After you import a surface into your model, there may be areas of the surface that you do not need, or that appear to have errors. You can trim the surface model so that you focus on only the area you want to work with.

1. To trim a surface, first ensure the surface is visible and any background CAD data is invisible.
   

2. Zoom into the west side of imported surface model, where there are some colors that appear incorrect, in comparison to the surface around it. This indicates an error in the data source. To correct it, delete that area.
   

3. Zoom out or select View Extents.
   

4. In the Tree View, right-click the Surface node and select Edit Data.
   

5. In the Surface Data dialog box, select Trim.
   

6. Ensure that ALL the data has indeed been loaded into the model, especially for very large data sets.

Optionally, ensure that all ASC tiles are loaded, as they make up a large area. A site may be located at the junction of four tiles. Best practice is to load all the tiles, then pare it down so that you are focusing on only the area that you want. Save the pared-down area of ASC tiles as an InfoDrainage file. Then, import the new .iddx file.

7. In the Trim Surface dialog box, notice this data matches the imported surface data, where each circle represents a point in the data table.

IMPORTANT: When defining the trim surface, indicate the surface you want to keep, not the piece you want to discard.

8. Ensure that the Select arrow is highlighted; in the window, the cursor appears as a circle with crosshairs.
   

9. Place the cursor in the upper-left corner, and then click and drag toward the lower right, so that most of the surface is selected, except for the area on the left where the missing data is.
10. Let go of the mouse button.
    

11. Click OK.
12. In the Surface Data dialog box, click OK.
13. You are prompted to either create a new file or overwrite the existing surface. Click Overwrite Existing.
14. In the Plan View, the model updates.
    

15. Save the file.