What is 3D scanning? How do 3D scanners work? All3DP answers all the essential questions about using a 3D scanner.
3D Scanner 101: What is 3D Scanning?
3D scanning is the process of capturing a digital representation of a physical object. This data can then be used to 3D print a physical replica of the source object.
Alternatively, the data can be remixed and modified to create new variations of an object — also 3D printable — without altering the source object.
A 3D scanner is by no means essential for successful 3D printing projects, but it’s a useful expansion for your “Maker Toolkit”, dramatically opening up the variety and range of objects you can select for 3D printing.
There are a variety of 3D scanning techniques and technologies currently available. This 3D scanner 101 will help you learn about the fundamentals of 3D scanning, and decide whether it’s going to be a good fit for you and your 3D printing project.
3D Scanner 101: Learning the Lingo
Let’s kick things off the essential terminology you should know. Don’t be scared, there are only three items on this list!
- Point Cloud: In a coordinate system, a point cloud is a set of data points that represent the surface of an object.
- Mesh: A mesh is a collection of vertices, edges, and faces that clearly defines the shape of a 3D model.
- Watertight: A model is watertight when it has a continuous outside surface — or mesh — that’s necessary for successful 3D printing. For example, an object like a ring, even though it has a hole in the middle, has a continuous outside surface and can be 3D printed.
See? That wasn’t so painful!
3D Scanner 101: How do 3D Scanners Work?
There are many 3D scanners on the market to choose from. Some of them are open source, some of them are not.
Made by one of the most recognizable brands in 3D printing, the MakerBot Digitizer works with a laser and camera mechanism, together with a rotating platform. This 3D scanner can capture objects that are 8×8 inches big, and 2×2 inches small.
Other methods use 3D scanning software like Autodesk 123D Catch or a modified Microsoft Kinect. Because the Kinect is handheld, there are no theoretical limits to the size of the object you can 3D scan; rather, the constraints come from the person wielding the 3D scanner! The Fabscan Pi Project is another exciting option, where you can build your own 3D scanner using a Raspberry Pi.
Breaking the process down into smaller chunks, there are several things to know about how a typical 3D scanner works:
- Laser & Camera: A laser line is projected onto the surface of an object. As the object rotates on the turntable, the camera picks up the laser line and processes it into data points, known as a point cloud.
- Turntable: The turntable slowly spins the object so the camera can gradually capture every angle and contour.
- Point Cloud: Data points in space recreate the object’s surface digitally.
- Mesh: The point cloud is then stitched together using software, to create a virtual representation of the source object with a complete, watertight mesh surface.
The accuracy of your 3D scan is dependent on several factors, including the resolution of the camera, lighting, and the surface quality of the object. The MakerBot Digitizer, for example, has a dimensional accuracy of +/- 2mm.
3D Scanner 101: What Can You Do With a 3D Scan?
When you find something worth 3D scanning, a 3D model of a real-world object can make an awesome starting point for a new project. You can scale the model up or down in size, modify details and features, and remix your scan however you like. And of course, you can go ahead and 3D print it, too!
- 3D scan as a reference: A 3D scan can be used to create a custom mold of an object so that it can repeatedly be cast in other materials. If you want to create a jelly or chocolate mold out of a smartphone, for example, there’s nothing to stop you.
- 3D scan to replicate: 3D scanning is a fantastic method for preserving and archiving precious or fragile objects. If you work in a natural history museum, for example, you could scan fossils and other artifacts to make digital copies. These can be 3D printed and turned into tactile exhibits.
- 3D scan to remix and modify: 3D scanning is only the starting point. Once you’ve captured an object, you can modify it’s properties however you like. Make a sculptural object into a functioning flower pot, for example, or restore the arms to the Venus de Milo!
As you can see, the possibilities are quite exciting. The booming popularity in 3D Selfies stems directly from the technology of 3D scanning, where people pose to have their features captured and recreated as mini-statuettes.
3D Scanner 101: What Color Shades are Best for 3D Scanning?
Unfortunately, you can’t just 3D scan anything. Some objects are more suitable for 3D scanning than others. One important consideration is color. Lighter objects are easier to scan, whereas darker objects provide more of a challenge.
Why? Because dark objects cause the laser line to be partially absorbed by the object, making it harder for the camera to distinguish. Visually, the laser line will appear murky, or diluted. Here’s a color guide
- Easy: An object that’s white or red in shade, with no glossy surface
- Medium: An object that’s yellow or gray, with little or no gloss
- Hard: An object that’s dark, glossy, fuzzy or transparent. Difficult colors are green, blue or purple.
With dark colored objects that are difficult to 3D scan, one trick is to coat them in a lighter color before 3D scanning. Household items like baby powder and flour would be ideal. However, the surface grain of the coating agent may also show up in the 3D scan.
Where an object is translucent (for example a glass tumbler), shiny, or has a fuzzy surface, the camera is disrupted from seeing the laser line because the laser is being reflected in multiple directions. Again, you can try coating the object to reduce the laser reflection or absorption, like a matte paint.
3D Scanner 101: Optimizing Your 3D Scanner Setup
When setting up your 3D scanner, make sure to place it on a flat, stable work surface. Ensure that no parts of the machine are hanging over the edge of the surface.
It’s also a good idea to set up the 3D scanner facing the nearest wall. The darker the wall, the better. Ideally, the lasers in the 3D scanner should point towards the wall while avoiding any windows or other sources of bright light.
Why? Because bright light that’s direct or reflected into the camera can interfere with your scan, causing the scan of the object to be less than optimal.
Follow the instructions provided with your 3D scanner for optimal calibration. Calibration ensures that the positions of the lasers and turntable are recorded accurately, so the 3D scanner can capture best possible 3D scans.
3D Scanner 101: Lighting Tips & Tricks
Funnily enough, the only time you need any light source at all is during the calibration routine (meaning you can 3D scan an object in pitch dark).
If you have to calibrate in a darkened workspace, avoid direct overhead light. Instead, use a lamp or flashlight behind your 3D scanner, so the light source is not shining directly into the camera.
For general 3D scanning, scanning in low light is best. If you have difficulties 3D scanning a dark object, try shutting off the lights in the room completely (and draw the curtains).
Hanging black felt on the wall facing your 3D scanner is also useful. By darkening the surface of the wall, any light in the room won’t bounce off the background and cause bright spots that the camera could misread as part of the laser line.
3D Scanner 101: Conclusion
That’s the end of our 3D Scanner 101. Did we miss any important topics? Do you still have some burning questions? Let us know in the comments and we’ll respond in a future update.
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