This is a correction to a post I made a while ago, concerning creating a Civil 3D surface from LAS point cloud data containing point classifications. Thanks to some information from a reader, I made some testing on the process I outlined earlier and determined it DID NOT filter out non-ground classified points from the surface. It only affects how they are displayed in the current drawing.  However, thanks to the fact that Civil 3D is built on the foundation of Map 3D, we can use some of those tools to process an imported ReCap file created from an LAS file containing ground point classifications.

As noted in the previous post, starting with Civil 3D 2018, you will notice the conspicuous absence of the old Point Cloud section in the Prospector. Many users utilized the old point cloud creation method to read and control the visualization of classified points in their point clouds, to display only the ground points, for example. Autodesk ReCap is now the preferred method to create, manage, edit and export point cloud data for use in Civil 3D, AutoCAD, Revit and many other applications.

The issue with importing .LAS format files into Autodesk ReCap, is that there is currently no way to filter the points by classification from within ReCap.  You can visualize them by RGB, Elevation, Intensity, Normal or Scan Location, but there currently is no Classification filter.

The solution to this lies within Civil 3D with Map 3D tools. When creating and exporting a .RCP file created from .LAS file containing classification data within Autodesk ReCap, that same classification data remains within the .RCP file.

Import your .RCP file into Civil 3D as you would normally, using the Import Point Cloud command in the Insert ribbon tab. Once your point cloud is inserted, select it so that the Point Cloud contextual ribbon displays.  On the left side of the ribbon, you will see the button that displays “Scan Colors”. 

Select the pulldown arrow beneath it and choose “Classification”.  You will see your point cloud change colors to reflect the standard classification colors. Use this to verify that your point cloud, does in fact contain point classifications.  As stated above, the Create Surface from Point Cloud command will not currently use these classifications as filters.

To filter out all information, other than ground classified points, we will turn this ReCap point cloud into a DEM file using the Map 3D command.  Switch your Workspace from “Civil 3D” to “Planning and Analysis.  This will switch the ribbon to the Map 3D workspace (no need to start Map 3D separately).

In the command line, issue the command: MAPCREATEPCSURFACE

Select the inserted ReCap point cloud and hit Enter on your Keyboard. In the resulting dialog box, you will see that the program is going to create a GeoTIFF DEM image from your point cloud. Now for the magic part, click the Filter button on the lower left of the dialog. In the pop-up menu, select “2 Ground”, then the OK button.  This will filter all points out except the ground classified points when creating your DEM file.

Once your GeoTiff DEM file is created, it will contain only theh ground points.  From here, create a new Civil 3D surface and import the DEM file you just created as a surface definition.  You will now have a surface that ONLY contains Ground points, as well as being a little cleaner.

If you have any questions or want to know more, please email me at [email protected] for more information.  Follow me on twitter at Twitter.com/MarkSchnesk and on LinkedIn at www.linkedin.com/in/mschnesk/