Introduction to 3D scanning principles and techniques

3D scanning allows us to capture real-world objects in a digital format, which can be used for various applications such as virtual reality, product design, and 3D printing. This process lets us identify the exact shape and appearance of objects.

There are different types of 3D scanners and 3D scanning technologies. Some are suitable for short-range scanning while others are better for mid or long-range scanning, depending of course on the size of the scanned object. The 3D scan technology used for small objects is very different from the one used for large objects (e.g. a building). However, the basic principles are more or less the same: sensors or cameras are used to collect information about the object’s surface geometry and/or texture.

One common method is structured light scanning, where a pattern of light is projected onto the object and then captured by a camera. By analyzing the distortions in the pattern, the scanner can determine the 3D shape of the object.

Another method is laser scanning, which measures the distance between the scanner and the object at multiple points. This creates a point cloud, which is a collection of data points in 3D space that represent the object’s surface. Laser scanners are very popular and come in many designs from handheld portable units to single point long range trackers. Some of the benefits of 3D laser scanners are: they are able to scan tough surfaces (such as shiny or dark finishes), they are less sensitive to light conditions and ambient light, are often more portable and have a simpler design, easier to use and have a lower cost.

There are also contact scanners, which use physical contact with an object to create a 3D model by measuring the object’s shape and features. CT and MRI scanners are often used in medical imaging to create 3D models of the human body or objects by taking multiple cross-sectional images and reconstructing them into a 3D model.

Most of the above types of 3D scanning require expensive hardware and software. A more accessible and popular option is Photogrammetry. This technique uses multiple photographs of an object taken from different angles to reconstruct a 3D model. Specialized software compares the photos and uses the differences between them to calculate the object’s shape. To 3D scan with a phone, drone, or camera, you need photogrammetry software. There are several 3D scanning mobile apps available (and some of them are free). More info can be found in this article: “The Best 3D Scanner Apps for iPhone & Android”. Desktop PC applications are also available. 3DF Zephyr is a very popular choice (and free for personal use). You can check out this Getting Started tutorial. Some other free and open-source choices are MeshRoom and MicMac.

There are also some great DIY projects available online for building a 3D scanner with 3D printed parts. You can check out some of these open-source DIY projects here: The 10 Best Open-Source 3D Scanners in 2023.