Laser Scans and Precision Modeling

Laser Scans and Precision Modeling

As we mentioned in our previous post on Total Stations, electronic measuring devices are the standard when it comes to gathering precision data for 3D modeling. Laser scanners are becoming more powerful, less expensive, and thus more accessible for folks looking to create very precise 3D models. For what we do here at Fat Pencil Studio there are plenty of times when simpler, more representational models will do. But for the times when a project demands a great degree of precision, there’s nothing quite like having the rich information you get when you’re working with point clouds from a 3D scanner.

 

Measuring from a point cloud with AutoDesk ReCap

Measuring from a point cloud with AutoDesk ReCap–better than being there.

The way a 3D scanner works is by spinning an angled mirror that then reflects a laser beam cast from the device. The spinning mirror forces the laser beam into a circular path that detects surrounding objects and is then beamed back to the receiver. At the same time, the entire assembly slowly rotates so the scanner eventually captures 360 degrees’ worth of information. As the laser beam is spun around, it collects hundreds of thousands of data points that are then recorded and stored in what’s called a point cloud. The point cloud is a spatial arrangement of all these data points, essentially a pointillist 3D model.

 

A spinning mirror reflects a laser beam generated by the scanner. The whole assembly rotates as the laser spins.

Point clouds are great for their data richness and surreal aesthetic quality. But as we find so often in our work, too much data is almost as bad as no data at all. In order to turn a point cloud into an easy-to-manipulate visual tool, we have to cut out the “noise.” We use the point cloud data as a reference to create SketchUp models of a space or scene that are clear, very accurate, and presentable.

 

AutoDesk's example of their scan-to-mesh process that translates point clouds into simpler, more manageable meshes.

AutoDesk’s example of their scan-to-mesh process that translates point clouds into simpler, more manageable meshes.

Laser scanners each come with their own proprietary software for accessing point cloud data, which in our experience ranges from rudimentary to very clunky. Personally, I prefer AutoDesk ReCap for its ease of loading and syncing multiple scans in a single scene, as well as taking and recording object measurements. You get tools that allow you to easily reset axes to objects so that measurements are less distorted, and the option to quickly section out which portion of the point cloud is shown, making navigating much easier. Another nice feature of ReCap is the ability to switch between views quickly without losing what you’ve already done.

If you’re interested in learning more about how laser scanners work, this marketing video by FARO gives a great breakdown of the mechanism:

 

About Jannine Hanczarek

Jannine Hanczarek is a Technical Illustrator at Fat Pencil Studio.