Laser scanning point cloud in AutoCAD
A point cloud in laser scanning is a large set of points captured by a measuring device, in our case, a terrestrial laser scanner with high speed, capable of capturing up to 2 million points per second. Laser scanning technology allows the "transfer" of real-world objects with their actual dimensions into a digital form for further processing on a PC.
Stitched, processed, and cleaned point clouds, free from extraneous objects, can be the output of our work for companies experienced in handling such data. In some cases, users may encounter difficulties when working with point clouds, so below, we will discuss the main issues that arise when working with point clouds and provide explanations on how to resolve them.
How to prepare a point cloud for use in AutoCAD
Inserting a point cloud into a new AutoCAD drawing
Adding a point cloud to an existing AutoCAD drawing via external reference
Point cloud display settings in AutoCAD
Transforming a point cloud to a local coordinate system
How to prepare a point cloud for use in AutoCAD
Creating drawings from point clouds requires some experience with AutoCAD, as it often involves drafting as-built plans and other technical drawings. We recommend using AutoCAD version 2016 or newer for working with point clouds because earlier versions lack the functionality and tools needed for efficient point cloud processing.
For handling point clouds in AutoCAD, the data format from ReCap is typically used. ReCap is a small, free application available for download on the official Autodesk website. It structures standard point cloud formats for seamless integration with Autodesk software such as AutoCAD or Revit.
For more information on point clouds, their parameters, and structure, you can refer to the provided link.
How to insert a point cloud into a new AutoCAD drawing
After processing the point cloud file in ReCap, a file with the extension *.rcp is generated along with a Support folder. This *.rcp file is required for import into AutoCAD.
Option #1:
For a new drawing, simply drag the file into the drawing area.
After dragging the file into the drawing area, you need to input:
Insertion point coordinates (or press Enter to insert at 0,0,0)
Scale factor (always "1" or press Enter)
Rotation angle ("0" or press Enter)
Once these steps are completed, the point cloud will be inserted into the drawing. To view it, simply click "Top" on the view cube or double-click the mouse wheel.
Option #2:
In the Insert tab, go to the Point Cloud section and select Attach.
In the window that appears, specify the path to your *.rcp file.
In the dialog box that opens, uncheck the boxes for Insertion Point, Scale, and Rotation to insert it by default at the file's origin coordinates, with a 1:1 scale and no rotation.
Click OK to complete the insertion. This will place your point cloud into the drawing.
(If you need different settings, adjust the values as required).
How to add a point cloud to an existing AutoCAD drawing using an external reference
Due to the large volume of data contained in point clouds, they take up significant space and are typically transmitted separately from drawings in archives, often uploaded to cloud storage. If you received drawings based on a point cloud in the .dwg format with the point cloud already inserted, and the point cloud downloaded separately, you need to specify the path to the point cloud on your computer in the drawing.
Here’s how you can do it:
First, extract all files into a separate folder. In the folder, there should be an .rcp file and a folder with the same name as the .rcp file followed by the suffix "Support".
Open the .dwg file and select the inserted point cloud (step #1 in screenshot) — it might appear as an empty cube with a path label, for example, "E:\2024\37-Gorny\04-Output\Gorny-Racap\Gorny.rcp".
After selecting it, the Point Cloud tab will open. Click the External Reference button (step #2 in screenshot).
In the list that appears, click on the row with the cloud icon (step #3 in screenshot).
In the list below, find the Saved Path field (step #4 in screenshot). Change the path by specifying the path to the .rcp file on your computer and click Open (step #5-6 in screenshot).
Point cloud display and visualisation settings in AutoCAD
For more convenient work with point clouds in AutoCAD (AutoCAD or Civil), you can use the display and visualization settings available in the Point Cloud tab by simply selecting your inserted point cloud in AutoCAD. Here, you can adjust the point size, level of detail, transparency, and stylization, which can often enhance the visual representation of the point cloud for more comfortable work.
By default, point clouds use the RGB colors from the scan files, but you can choose colors from other stylizations.
Scan Color: Each point is stylized based on the original colors from the scan file. If the scan file did not save colors, the points are stylized in grayscale.
Object Color: Each point is stylized according to the "Color" property of the point cloud object.
Normal: Each point is stylized based on the direction of the point's normal, using a non-editable color scheme.
Intensity: Each point is visualized based on the Intensity value.
Elevation: Each point is stylized based on its Z-coordinate value. An adaptive "Earth" color scheme is applied, based on the minimum and maximum elevation values in the point cloud.
How to convert a point cloud to a local coordinate system
Each point in a point cloud has coordinates (X, Y, Z). If we consider a point cloud from a single scan station, the origin (0, 0, 0) is located at the position of the scanner. If there are multiple scan stations, the point clouds from each station are combined (registered, stitched) into a single point cloud and unified coordinate system. The coordinate system can be either arbitrary, with the origin within the surveyed building, plot, etc., or local.
To convert a point cloud to a local coordinate system, special markers are used during field laser scanning operations. These markers are recognized by specialized laser scanning software. The coordinates of these markers are preliminarily determined using total station surveying. The obtained coordinates are then assigned to the corresponding markers in specialized laser scanning data processing software such as Leica Cyclone, Registr360, Faro Scene, Trimble Real Works, and others.