Aligning Objects with the Enhanced Transformation Tool
Introduction to the Transformation Tool
In this tutorial, we’ll introduce the enhanced transformation tool from 3Dsurvey 2.17, which allows users to align two objects based on a set of identical points. This function can be applied to various types of point clouds or meshes and across different data sources, such as combining photogrammetry with videogrammetry or aligning multiple terrestrial laser scans.
Working with Different Data Sources
The transformation tool is not limited to photogrammetry. It enables users to merge point clouds from multiple sources, including photogrammetry, videogrammetry from smartphones, and terrestrial laser scans. It also facilitates transforming objects between different coordinate systems. For this tutorial, we’ll demonstrate aligning a photogrammetry point cloud with a videogrammetry point cloud captured using a smartphone.
Initial Setup
We’ll begin with two point clouds. The first was created using images captured by a Phantom 4 drone, providing a broad overview of the site. The second point cloud, created via smartphone videogrammetry, offers additional detail from a ground perspective. Since ground control points (GCPs) were used, aligning the two clouds is straightforward and accurate.
Defining Ground Control Points (GCPs)
Navigate to the CAD tab, create a new layer for the drone point cloud, and assign it a color. Locate and mark the GCPs that are visible in both datasets. At least three points are required for the transformation, but adding more will improve accuracy. After marking three GCPs on the first dataset, create another layer for the phone videogrammetry point cloud and repeat the process. It’s essential to ensure that GCPs in both datasets share the same names to establish a connection.
Executing the Transformation
Once the GCPs are set, go to the point cloud tab, select the object you want to transform, right-click, and select “Transform.” Uncheck the option to apply the transformation to the entire project, then calculate the parameters. Select the GCPs from both datasets—those for the object you want to move (phone dataset) and the reference points (drone dataset). As long as the points are correctly named, they will automatically match.
Finalizing the Alignment
Click “Calculate” to generate the transformation parameters, and observe the transformation preview. Once satisfied, confirm the transformation, and the point clouds will align perfectly. At this stage, you can turn off the CAD layer for the phone point cloud if it’s no longer needed. The result is a more detailed and accurate 3D model, combining data from both the drone and phone sources.
Conclusion
After aligning the point clouds, you can decide whether to merge them into a single model or process them separately. This enhanced transformation tool offers greater flexibility and precision in combining data from multiple sources, helping you create high-quality 3D models with ease. That concludes this tutorial—hope it brings you great results, and see you in the next one!