3D scanning uses flashing light, photographs, or even lasers to analyze a real-world object and gather data on shape, appearance, and even color. The collected data can then be used to construct digital 3D models, and can be applied to a huge array of applications from reverse engineering and prototyping, creating custom-fit orthotics and prosthetics, entertainment industry CGI, to projects like digitizing scientific and historical heritage collections.
Some of the most popular technologies include:
Structured Light Scanning
Photogrammetry is a form of scanning that uses a simple DSLR camera to capture photos around an object and measure the differences based on some clever perspective geometry. The best way to visualize this is to use your eyes — literally. Your eyes are using photogrammetry all the time. You have two eyes (two cameras), processing a live feed of your surroundings. Because your eyes are slightly apart, you’re getting two different inputs at slightly different angles.
3D scanning photogrammetry works the same way. Hundreds or even thousands of still photos are taken around an object from as many angles as possible. This data is then compiled and ultimately rendered and processed by software that calculate measurements and determine distances in order to form a complete 3D object. It’s a cheap, easy, and field-friendly form of 3D scanning.
Structured Light Scanning
Structured Light Scanning (SLS)
A structured light scanner works a bit differently. These 3D scanners project a specific light pattern onto an object, and film it with at least one camera (but usually two cameras) to capture the ways in which the object deforms the light pattern. By triangulating multiple images of the scan, you can calculate the dimensions of the object in all its complexity.
Most scanners use a pattern of alternating stripes, similar to the shadows cast by sunlight shining through blinds. With finely calibrated stripes and accurate cameras, it’s possible to measure the dimensions of very small details — even the minute variations in the surface of very tiny objects. By processing the resulting data in scanning software, you’re able to create a digitized, dimensionally accurate 3D model of the scanned object.
Think of LiDAR (or "Light Detection And Ranging") a bit like a bat's echolocation -- except that instead of pinging and recording data on sound waves, LiDar emits light in the form of a rapidly firing laser. The light emitted is quickly flashed from a laser light source, travels outward, and ultimately reflects off of things like buildings, rock faces, and tree branches. The reflected light energy then returns to the LiDAR sensor where it is recorded.
A LiDAR system measures the time it takes for emitted light to travel to the ground and back. That time is used to calculate distance traveled. Distance traveled is then converted to a 3D point cloud that makes up the 3D model itself. These days, things like automated self-driving cars even use a variant of LiDAR to rapidly record and respond to the changing world around them.