How to import a point cloud into a drawing and create a surface model?

As laser scan data collection becomes more common and replaces other large-scale data-collection methods, the ability to use point clouds in Civil 3D is critical. Intensity helps postprocessing software determine the ground cover type. While Civil 3D can’t do postprocessing, you can see the intensity as part of the point cloud style.
Import an LAS format point cloud file0422_Exercise_Denver.las into the Civil 3D template of your choice. As you create the point cloud file, set the style to Elevation Ranges. Use a portion of the file to create a Civil 3D surface model. No coordinate system needs to be set for this example.
Solution
  1. Start a new file by using the default Civil 3D template of your choice. Save the filebefore proceeding as 0422_Exercise_DenverUSA.dwg.
  2. In Prospector, right-click Point Clouds and select the Create Point Cloud option to display the Create Point Cloud Wizard.
  3. Set the name of the point cloud to Denver.
  4. Set the point cloud style to Elevation Ranges, and click the Next button.
  5. Use the white plus sign to browse to the LAS file.
  6. Select 0422_Exercise_Denver.las and select click Open. Click Finish. The New Point Cloud Processing In Background dialog will open. Click Close to dismiss.
    This file contains 4.7 million data points, so be patient while the file imports.
  7. When the point cloud has completed processing, zoom extents. Select the bounding box representing the point cloud to display the Point Cloud contextual tab.
  8. Select the Add Points To Surface command.
  9. Name the surface, set a surface style, and click the Next button.
  10. Choose the Window radio button and click Define Region In Drawing.
  11. Define the region by creating a window around the western half of the point cloud.
  12. Click Next to see the Summary page and click the Finish button. Close Panorama.
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Label surface contours and spot elevations

Showing a stack of contours is useless without context. Using the automated labeling tools in Civil 3D, you can create dynamic labels that update and reflect changes to your surface as your design evolves.
Open the0421_Exercise.dwg or (0421_Exercise_METRIC.dwg) file.
Label the major contours on the surface at 2' and 10' (Background) or 1 m and 5 m (Background).
Solution
  1. Select the surface. From the TIN Surface contextual tab ➢ Modify panel, click the Surface Properties icon.
  2. On the Information tab, change the style to Contours 2' and 10' (Background) or Contours 1 m and 5 m (Background).
  3. Click OK to close the dialog and press Esc to deselect.
  4. From the Annotate tab ➢ Labels & Tables panel, click the Add Labels button.
  5. Set Feature to Surface and Label Type to Contour – Multiple.
  6. Set Major Contour Label Style to Existing Major Labels and Minor Contour Label Styleto <none>.
  7. Click Add.
  8. Pick a point on one side of the site and draw a contour label line across the entire site. Press Esc to exit the command.
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Prepare a slope analysis

Surface analysis tools allow users to view more than contours and triangles in Civil 3D. Engineers working with nontechnical team members can create strong, meaningful, analysis displays to convey important site information using the built-in analysis methods in Civil 3D.
Open the0420_Exercise.dwg or (0420_Exercise_METRIC.dwg) file.
Create a slope banding analysis showing slopes under and over 10 percent and insert a dynamic slope legend to help clarify the result of the analysis.
Solution
  1. Select the surface. From the TIN Surface contextual tab ➢ Modify panel, click the Surface Properties icon.
  2. On the Information tab, set the Surface Style field to Slope Banding (2D).
  3. Switch to the Analysis tab for the Slopes analysis type.
  4. Set Ranges Number to 2 and then click the Run Analysis arrow.
  5. Change both the maximum slope for ID 1 and the minimum slope for ID 2 to 10 percent.
  6. Click OK to close the Surface Properties dialog.
  7. Select the surface to display the TIN Surface contextual tab.
  8. From the TIN Surface contextual tab ➢ Labels & Tables panel, choose Add Legend Table.
  9. Enter S ↲ and then D ↲ at the command line and pick a placement point on the screen to create a dynamic elevations legend.
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How to modify and update a TIN surface?

TIN surface creation is mathematically precise, but sometimes the assumptions behind the equations leave something to be desired. By using the editing tools built into Civil 3D, you can create a more realistic surface model.
Continue working in the file from the previous exercise or open the0419_Exercise.dwg or (0419_Exercise_METRIC.dwg) file.
Use the irregular-shaped polyline and apply it to the surface as an outer boundary of the surface. Make the boundary a destructive breakline.
Solution
  1. Expand the Surfaces ➢ Existing ➢ Definition branches.
  2. Right-click Boundaries and select the Add option.
  3. Verify that the check box by Non-Destructive Breakline is unchecked and click OK. Select the magenta-colored polyline to complete the boundary addition.
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How to create an existing ground surface using points?

The most common way to create a surface model is by adding point data to the definition of a surface.
Open the0418_Exercise.dwg or (0418_Exercise_METRIC.dwg) file. Create a new surface called Existing. Add the point group Topo to its definition. Leave the default styles.
Solution
  1. On the Home tab ➢ Create Ground data panel of the ribbon, click Surfaces ➢ Create Surface.
  2. Name the surface Existing and click OK.
  3. In Prospector, expand the Surfaces ➢ Existing ➢ Definition branches.
  4. Right-click Point Groups and select Add.
  5. Select the point group Topo and click OK.
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Working with Large Surfaces

A surface has a limit to the number of points it can contain before caching its definition to an external file. The only way to prevent this is to reduce the amount of data in the surface definition. If this is not an option, the cache file will be created in the same folder where the drawing file has been saved. This file must remain in the folder with the drawing file for the surface definition to remain in the drawing. If the cache file is deleted, moved, or renamed, the surface will no longer appear in the Prospector or function in the drawing. What will remain in the drawing will be a proxy entity.

The cache file will bear the name of the drawing file along with its AutoCAD object handle ( <drawing_name>_<surface object handle> ). For grid surfaces, the limit for the number of points is about 1 million, and the file extension of the cache file will be .grs. For TIN surfaces, the limit is about 2 million, and the file extension of the cache file will be .mms. There are several options for working with large surfaces depending on the situation:
Data Clip Boundaries
As discussed earlier, a data clip boundary is a type of boundary that can be added before any elevation data is added. This is the best option to use if you have information covering a large geographic area but are working only in a smaller area.
Cropped Surface
The Create Cropped Surface command can be found in the contextual tab of your surface, hidden in the Surface Tools panel flyout. This command will break off a piece of a surface model and allow you to send the smaller piece to a new drawing. This is a fast way to create a new drawing containing the desired surface data. The major disadvantage to the cropped surface tool is that there is no connection between the original surface and its spawn. In other words, if the original surface is changed, the new surface will not be affected.
Data Shortcuts
The best of both worlds, data shortcuts allow you to work in a new file but remain connected to the surface’s source data. Another major advantage of using data shortcuts is that multiple users can access the surface data without duplicating it.
Here are some other hints that will be helpful in increasing performance when working with large surfaces:
  • Turn on the Level Of Detail option in the Views panel of the View tab.
  • Do not use the Rebuild-Automatic option.
  • Turn off the selection preview on the Selection tab of the Options dialog.
  • Clear the Show Tooltips option in the Surface Properties dialog.