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Manage Point Clouds in AutoCAD Map 3D
21 Jul, 2010 By: Michael SchlosserAccess, stylize, and filter LiDAR data with the new tools in AutoCAD Map 3D 2011.
AutoCAD Map 3D 2011 is the latest version of Autodesk's software for creating and managing CAD and spatial data. My favorite features of this release include the new point cloud tools for viewing, querying, and analyzing 3D laser scanning and LiDAR (light detection and ranging) data sets.
LiDAR is a system for collecting topographic information whereby laser-equipped aircraft collect points in three dimensions, creating data sets known as point clouds. These point clouds are then used to locate topographic features, define feature geometries, and create 3D surfaces.
Point clouds often contain hundreds of millions of points and can be difficult to work with using traditional AutoCAD methods. However, the new Point Cloud Manager in AutoCAD Map 3D 2011 is designed to handle large numbers of points and enhances the ability to use these large LiDAR data sets. Plus, with AutoCAD Map 3D we have the additional benefit of being able to assign a geographic coordinate system so that we can use these point clouds in a geographic context with design information and other geospatial data sources.
In this article, I'll explain how to use the new point cloud tools in AutoCAD Map 3D 2011 to access, stylize, and filter a LiDAR point cloud corresponding to a municipal downtown area. I will also show how to use point clouds to first create a 3D surface, and then analyze the results. A video demonstrating the techniques discussed below is available via my blog.
Adding a Point Cloud
Point cloud data sets are large, often containing many millions (and sometimes billions) of points. To work effectively with such a large number of points, we can use the new Point Cloud Manager to index the point cloud data. The most common formats for LiDAR data include the LAS (LiDAR Aerial Survey) and XYZ formats. The LAS format is particularly useful because it includes 3D coordinate data, as well as point classification information that helps distinguish points corresponding to ground, vegetation, building, and other types of surfaces.
Point cloud data representing buildings, vegetation, and ground.
Let's begin by creating an index for the LAS file. In the Map Task pane, activate the Display Manager tab, then click Data > Add Point Cloud Data > Create New Index to reveal the Point Cloud Manager. The Point Cloud Manager displays summary information about the point clouds that we are currently working with. This information includes source file name, corresponding coordinate system, current filters being applied, output file name, and creation date. (Note: This area will be empty if no point clouds have been added to the Point Cloud Manager yet.)
The Point Cloud Manager in AutoCAD Map 3D 2011.
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About the Author: Michael Schlosser
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