101s: Intro to 3D Scanning
Disclaimer: Thanks to the LaGuardia Studio for providing access to several of the 3D scanners mentioned in this post.
***This post has been updated as of March 2017
It is quite difficult to provide an introduction paragraph for a technology whose scope is as wide and deep as 3D scanning! As you will read in this primer to the process, 3D scanning provides opportunities to make feats in a number of fields that were once impossible possible, more accurate, and more versatile. Combined with 3D modeling and printing, we have an unstoppable trifecta of tools that are world-changing level, and you can access and use them! It can't get more exciting than that!
3D Scanning 101
How it works
The foundation of 3D scanning lies in a device (handheld or not) that works alongside software to detect an object in space, and record it through references it makes upon the object in three dimensions. All scanning has this at its base, with the execution differing from device to device.
There are two types of scanning processes, contact and non-contact scanning. Contact scanning uses a probe to touch the object, which sits upon a flat platform as it is scanned. This post will focus on Non-Contact Scanning, when the object is not physically touched.
Under the umbrella of Non-Contact Scanning lies four main scanning techniques, which includes Time-of-Flight Laser Scanning, Optical Laser Scanning, Structured-Light scanning, and Photogrammetry:
Time-of-flight scanners are generally used to record very large spaces, such as entire buildings or stretches of landscape. It uses a laser range finder, which shoots a pulse of light across the area. When the light hits the end of an object in the space or the physical end of the space, the beam bounces off of it and returns to the scanner. The distance is then calculated from these results, creating a to-scale scan.
Standing on a tripod, the physical scanner can only record what’s in its direct field of view, so moving and rotating it is required to scan a wider range.
A great example of this is a recent project of the Cooper Hewitt Design Museum in NYC, in which the enitre exterior and interior of the building was 3D scanned and generated into a printable model free to download by anyone.
Laser Scanners emit light through optical amplification, or light that is enhanced and refined. These scanners tend to be extremely precise, for they emit a very small laser beam that can travel relatively long distances while retaining accuracy. The light can also be projected as a dot, line or a plane, creating further definition in the scan.
After the laser beam is fired onto the object, the scanner then uses a camera to look for the location of the beam; depending on how far away the laser strikes the surface, the beam appears at different places in the camera's field of view. The scanner then takes the data and references from the the laser beam on the object in conjunction with the camera to form a series of triangle-shaped sections across the model. This process is called triangulation, and is used to create an accurate three dimensional model of the object being scanned.
Structured-light scanning uses a “white light” source, such as an LED or halogen, and a camera. When the light is shone upon the surface of the object, it is projected as a pattern (ie, a grid). The scanner's camera then records the pattern as it deforms and molds itself around the object, understanding it in three dimensions.
Lastly, a relatively inexpensive way of scanning is by using a process called photogrammetry. Photogrammetry uses images taken with numerous (high definition) cameras set up 360 degrees around the object; those are then processed by software, which generates the 3d shape by comparing two or more images taken at different distances from each other (seeing a common thread bewteen processes?). This is generally less expensive because it only requires a camera and software that can compare the images.
An example of this was used to re-create supermodel Karly Kloss as miniature fashion dolls for a Vogue photo story; also, Sarah was the technician responsible for cleaning the mini Kloss’ once they were printed (Check out the video in the article!)
Tips and Tricks and FYIs
Light, distance, shapes, resolution, image capture- with all that context in mind, here are some things to think about when scanning bodies and objects, if you plan on utilizing it:
Be on the Light Side: The scanner will have great difficulty successfully picking up details on objects of dark hues, for those shades absorb light, skewing the scanning process. Wearing light colored clothing, painting your object a lighter color, and/or even placing lighter color marks or stickers on the object will help resolve this issue.
Matte, Matte, Matte: Since all 3D scanners use some sort of light source to render an accurate model, any (highly) reflective surface will cause all sorts of interruptions in the scans as light bounces off of or blows outs the object. In our personal experience, areas with higher gloss will not even show up in the scan. A matte surface will not only make for a better scan, but a faster scanning process as well. Spraying a shiny object with matte fixative and/or dusting mattifying loose powder over it can resolve this issue.
Opaque only: Anything that light can pass through will not scan. This makes items like lenses and other clear plastics not ideal. To the left, what happens when a laser scanner attempts sunglasses.
Too Simple: A bit of a surprise thought, but something as simple as a white cube can be deemed a bit tricky for a scanner to capture. Too many self-similar faces can be confusing to the scanner because it may think it is picking up similar looking parts of the object over and over again, causing it to become confused and lost in space. The example to the left shows the difficulty of a white box's ability to be scanned, for its sharp corners and all-white color (with little variation), causes the scanner to lose tracking. As the scanner rounds the corner, it can no longer see the previous face, which it needs in order to understand where it is in space. Creating unique markings on the obeject's surface, like a randomized dot pattern, and scanning slowly around corners can help resolve this issue.
Keep Undercuts to a Minimum:
To the left, specific areas of the dragon skeleton will be hard to scan, including under the jaw to the roof of the mouth, inside the pelvic bone, and behind the ribcage. These areas are going to be difficult for the scanner to see due to the obstructions in front. It also might be difficult to get the scanner in range with physical obstructions in the way.
The term undercut in a way speaks for itself, for it identifies a dynamic area of an object that curls under itself. A good example would be octopus tentacles or more organic shapes. These areas on an object are also normally unsupported, making them quite fragile and easy to break when handling them.
This is why molds in traditional sculpture can be made up of multiple parts-to work around the undercut-so when the mold is released, these areas do not get caught on the mold and instantly break. With scanning, these areas can be difficult to reach with a handheld machine and are many a time shrouded in shadow, making if difficult for it to read on the scanner. In most cases, the less complicated the shape the better; if your object is more ornately shaped, you may have to perform multiple scans, re-positioning the object each time, then registering them together in software.
Hair Doesn’t Scan: Fiber like materials, such as hair or string, lack so little thickness that they most likely will not even show up in a scan, for they scatter light particles. It is far easier to 3D model them yourself than to scan them. To the left, a fun example of how Sarah's hair did not register to the scanner!
How 3D Scanning is Used
Scanning has been a huge way for the medical and dental fields to innovate, for 3D models can now be easily generated from CAT scans, MRIs, and Dental Cone Beam CTs. This makes designing fully-functioning, custom fit prosthetics and molds more precise and efficient.
The custom fit aspect of 3D scanning is what drives the plethora of start-ups in the industry that create all kinds of one-of-a-kinds, from shoes to suits. Nike has been 3D printing for years prototyping sneaker concepts, and Boeing utilizes the process to construct air ducts and other parts for their planes.
3D scanning is also becoming a prevalent process in contemporary art practices, as well as in the preservation of artwork and artifacts, especially what is non-archival, and what is slowly being destroyed or decaying.
All this barely scratches the surface for this versatile and flexible process. One thing to keep in mind with all this is that 3D scanning is not necessarily the step but a step to creating the final product; so depending on your project, 3D scanning may be an important process to incorporate into your practice and progress.
Scanning Sarah: From Concept to Practice
We have thrown so many words and concepts at you, so let us provide a working example of Sarah's process for scanning her torso and arms, which she used as the foundation for her 2015 New York Comic Con armor:
I made sure to come prepared for my session. The scanner that was going to be used was a handheld laser scanner that used triangulation to capture the person/object. Because of this, I made sure to wearing a flesh toned, shape-wear tank top, for its light color and tight fit would benefit the overall quality of the scan. I also applied white circular stickers to my torso and arms as well, placing them in general triangular shapes to aid the scanner in tracking my body. To completely set the scene, we adjusted the room's lighting to prevent the scanner from running into confusing areas either blown out by too much light, or covered by too much shadow.
To guarentee the best fit to my chest in its neutral position, I posed for the scan with my legs together, arms hanging down but away from my body (I locked my thumbs in the belt loops of my jeans to remain supported), making sure my shoulders were pushing downward and not shrugged to my ears. This way would get me the most accurate scan of my entire torso without my arms obstructing the shape, or the positioning of my hips distorting it.
I then scanned my arm outstretched in the same manner; however, this is one aspect I would have changed, for as you will see in future Chronicles posts, the fit of my armbands become a bit tricky to work work with, for in order to get them on, I had to have my forearm in the same position I was scanned in, or else tediousness ensued trying to attach them; they were also a bit uncomfortable when I tried to move within them, hence moving out of that static scan position. What I should have done was scanned my arm in the position it would be in the majority of the time, which would be hanging by my sides, so the fit would be more comfortable and natural. That is how accurate scanning can be!
A total of four scans were performed, two on my torso and two on my arm, which were then melded together, or registered together, in GeoMagic, a great program for editing scans. We performed multiple scans of each part in order to get as much information as possible, and pick up what the previous scan may have missed. After a bit of retouching, and the deletion of the excess floating geometry, we had models ready for me to build on!
But Wait, There's More!
So now you understand a bit about how the technology works as well as its limitations, you probably want to get started! Here a few scanners we have come in contact with, all within a variety of price ranges, that are worth checking out, whether just online or through purchasing them:
This is a handheld scanner that is accurate to 1mm. It uses basic object recognition, a process that captures general areas of the object in space, and then trims any trivial or floating geometry once the scan is completed. It also has embedded editing tools in it’s software that lets you trim, stitch and crop your scans before outputting your file in a 3D printable format. The software is extremely user-friendly and great for beginners. The physical scanner is also nicely compact and easy to store.
We have found that these scanners are most successful in capturing larger objects like bodies and furniture- If you are looking to scan a tiny HD object, this is not the tech for you. One's lightning conditions also make or break the color of the texture map it picks up. It also tends to lose its tracking easily mid-scan, causing you to have to redo the scan, so it will take some time to develop a rhythm.
The NextEngine HD scanner is accurate to .12 mm. It uses electro-optical architecture alongside algorithms to coordinate an array of lasers shooting parallel beams, resulting in higher fidelity scans. Another desktop scanner, the NextEngine outputs great color texture maps, and features a rotating bed with a tilt function for getting the often hard-to-reach top surfaces or undercuts, something many desktop scanners struggle with. This scanner is great for small objects.
Another desktop scanner similar to the MakerBot Digitizer, the Matter and Form can capture a scan in roughly 5 minutes. It features a vertically moving camera in conjunction with a rotating base for scanning larger (taller) objects with decent accuracy, and creates watertight meshes that can be sent straight to a 3D printer, reducing post-processing time. However, it is always recommended to do your own scan clean-up in a 3D modeling software such as ZBrush, Meshlab, or Geomagic toget the best, printable result.
$14,000 - $27,000
The Artec scanner can produce extremely high resolution (To acheive this though, it has very specific PC hardware requirements). When running well these powerful scanners capture color information at 24 bits per pixel, with resolutions of up to .1 mm and accuracy of up to .05 mm. Speaking of powerful, the scanning software has very strong editing tools for producing an accurate scan. If you are looking for a reliable, hi-res, and handheld scanner, this is a really good choice. Artec the company also has two scanner models with these capabilities, one for larger objects (such as people) and one for small objects.
$49,900 (probably "cheaper" now!)
With its fun, futuristic design, the (now old) ZScan was one of the first self-positioning handheld scanners on the market at the time of its release. It is a widely versatile device that is easy to set up and easy to use, making it great for those with little experience. Some specs: it scans at 150 dpi, with an accuracy of up to 50 microns, and 24 bit sRGB for color mapping.
$11,000 - $12,000
This handheld scanner is geared towards professionals, and can be used for a variety of applications like construction, industrial engineering, and forensics. It has a lightweight carbon fiber body, making it more ergonomic and mobile. With an overall accuracy of 1 mm, it has an indoor scanning volume of up to 8 cubic meters. Faro also offers its own post-processing software separate from the scanning software, self-containing the process.
Free for Students and Educators
As of 2017, free phone scanning app Autodesk 123DCatch is no longer downloadable, due to Autodesk further developing and monetizing their scanning offerings. The loss of 123DCatch is just one example of many companies putting dollar signs on their free 3D apps; however you get what you pay for, with these updated applications providing more options and higher quality results that its predecessors could achieve. Students and faculty, take advantage of academic discounts offered by most companies (especially Autodesk)! We also recommend checking out this article that puts other free phone scanning apps to the test.
ReMake acts as 123DCatch's replacement, but acts very differently to the former fan favorite. Instead of a phone app, ReMake is downloaded to your computer, and images taken on your phone are then uploaded into it (it accepts up to 214 images). The remainder of the process is the same- after adding your 60-214 images into the software, they are then uploaded to a server, which generates a 3D model from them. The model can then be downloaded.
In our personal experiences with this process, ReMake is significantly less seamless than 123DCatch, and it takes many more a scan to get a result that is relatively close to what your object looks like. Be ready to tinker, try, fail, and develop your own specialized system/rig for getting your desired result.
$179.00 - $3499.00
(standard license - professional license)
Although it uses photogrammetry, PhotoScan differs from other phone scanning apps in that it doesn’t use an app to generate the scans, requiring that the user take their own images and load them into the software. The software is very complex, and because of this, there can be a bit of a learning curve to acclimate to the interface; however, if the images used for the scan are of good quality, the potential for extremely accurate and hi-res scans make this software very competitive with some of the higher resolution scanners on the market.
So, there you have it! If you have held onto the end of this post, CONGRATULATIONS! You now have TONS of knowledge!
As mentioned in the post, 3D scanning is an incredibly versatile technology that can be used
as the step or a step to making your project all the more specific and sucessful.
And if you are just beginning your 3D printed journey, scanning an object, and then playing around with it in 3D software is a great way to get to know the process and the interface of your tools.
So, scan away! We send you forth to make amazing things!