Three-dimensional scanning

Three-dimensional scanning is often used for reverse engineering. Scanning a part, or an assembly of parts, results in a 3D model that can be used as the basis of a digital design. Some builders use 3D scanning to speed up digital design without creating dozens of models of components from scratch.

This technique can improve your workflow if you have a basis for your project and plans for major modifications. Scanning the frame and engine alone can provide a model that is useful for digitally constructing a fuel tank, fairings, and other major components of the bike.

Scanners use a variety of technologies, each with their own advantages and costs. At a high level, scanning is split into contact and non-contact varieties. Non-contact scanning is further broken down into active and passive styles.

Contact scanning is common in manufacturing and requires a probing device manipulated by a rigid and precise coordinate measuring machine (CMM). When the probe contacts - touches - the object being scanned, the machine records its location. The probe moves to another position and repeats the measurement as needed.

They are used for quality control purposes where specific dimensions are critical to the correct function of the part but are less interested in the specific shape of the part between these dimensions. Contact scanning is not particularly useful for custom motorcycle projects.

Non-contact active scanning uses radiation or light waves emitted by the scanner to measure distances to surfaces, which may be laser, structured light and modulated light. Thousands or millions of distance measurements are stored as a point cloud. Like a photographic camera, a 3D scanner has a limited field of view, so multiple passes from different directions are often required to build an accurate point cloud that covers the entire object.

Non-contact passive scanners do not emit any waves for determining distance. They rely on natural light or radiation reflected from the object. If you’ve seen photographic cameras used for 3D scanning, then you’ve seen photogrammetry. A single camera would be “photometric” scanning and a pair of cameras would be “stereoscopic” scanning. Arrays of multiple cameras can be used to collect multiple images at once.

Like many other digital tools previously exclusive to expensive industrial applications, 3D scanning devices have become cheaper and more accessible. While many builders can’t splash for a standalone 3D scanner to add to their toolkit, there are some cheaper options. If you have a high-end smartphone or tablet (with multiple cameras built in), there are now numerous apps that can turn it into a rudimentary 3D scanner. For the price point and with suitable patience, they may provide some useable models.

Many companies provide 3D scanning as a service – meaning they’ll scan your parts and supply a 3D model. This service may or may not fit into the budget of your build, but again, in specific applications, this might be valuable. There are also companies who have libraries of scanned parts that you can purchase and import into your modeling software.

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