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3D scanning the human body down to the finest details

3D scanning the human body down to the finest details

We are now over 7.5 billion people on Earth and, although some individuals are quite similar, no two people are exactly the same. With so many different faces, it’s no surprise that, over the course of evolution, the human brain has become a real Jedi master at recognizing the finest of details that set faces apart. This is likely the reason why we can usually easily distinguish an actual famous actor from a wax reproduction; our brains just figure it out! In order to be convincing, a statue made from a 3D scan needs to be accurate and have a high geometry resolution.

Improving the quality of 3D scans was a goal that incited USIMM to use peel 3d. Specialized in the machining of non-metallic materials, the company constantly deals with artistic projects and wanted to demonstrate the evolution of its CNC capabilities by comparing the results its team obtained from machining the 3D shape of an employee a few years ago to what they obtained today.

Scanning a living person is particularly tricky, according to Ms. Lea Lepage. “The scanners are typically very sensitive to micro movements, including something as subtle as breathing. It is therefore very challenging to scan a person.” To accomplish this feat, the USIMM team required a scanner that could tolerate a certain amount of movement—all while keeping a high level of resolution and accuracy in check. With a resolution of up to 0,5mm and a volumetric accuracy of 0,5mm/m; this is precisely what the peel 3d scanner had to offer.

They took the same employee, put him is a similar pose and proceeded with the scan, the same way they did a few years back. Once the scan completed, USIMM sent the 3D scan data obtained to their 5 axis CNC machine and made a full-size polystyrene reproduction of the employee. The results were incredibly stunning.

Comparison

Figure 1: Machined 3D scan obtained in 2013 with a Kinect (left) vs 3D scan obtained with a peel 3d scanner (right) 

The scan previously made with a Skanect machine did not compare with the results generated with peel 3d. “There was quite a big difference between the previous and current project,” said Lea. The new statue was much more realistic and more accurately represented reality. This test was very successful and is sure to convince a lot of USIMM’s potential new customers interested in having their own bodies turned into actual statues!

The smart reason to “copy” an existing object with a 3D scanner

The smart reason to “copy” an existing object with a 3D scanner

We often hear: “now that people have 3D scanners, aren’t you afraid they will start copying everything?” First, 3D scanners are not an enabler here; it was possible to copy existing objects long before the venue of this technology; if anything, it only took longer.

There are however cases where you need to work with existing parts, components or assemblies where having a virtual image of your component will save you a lot of time. Think of people modifying existing equipment and changing or improving its use.

Take the example of Ben from EMI Conception, a company specialized in the manufacture of high-end digging equipment for excavators from 1 to 30 tons. They also do all sorts of mechanical projects. Before getting their peel 3d scanner, they would use traditional measuring (a mix of tape measure and caliper) to model different existing components. Things could get creative with the use of cardboard templates and what not but in the end, and with a few iterations, it always worked. Adding 3D scanning into the project was a way for them to get things right the first time with a high level of confidence.

Ben recently reached out to us about a project involving a metal casting for a component used in airplanes. These castings used to be available as bare and would get machined to their final tolerances to reach certain higher tolerances required by the industry and be used as part of the plane cockpit. Unfortunately, in our specific case, the component was discontinued and no longer available; there is also no drawing or existing CAD file for the component either… Luckily, the owner still had a bare casting.

 

As you can see from the picture, the component has a very organic shape with very few aligned surfaces making it particularly difficult to model using traditional methods. To use Ben’s words, this is where a 3D scanner comes in handy! He started by 3D scanning the raw component, to keep it as a virtual archive, should they ever need to produce additional castings.

The part was then machined to tolerance and scanned again, this time to create a 3D solid in CAD to create drawings of the components, used for machining of future components. This is how the same 3D scanner was used twice on the same part but for 2 completely different uses; now that’s smart!

This is how making a simply copy becomes innovative and takes engineering further. Of course, a scanner good enough to be used on mechanical components could do just as good in a museum to archive artifacts or to capture the shape of a residual limb in a medical clinic.

Going back to Benoit’s project, he also sent me a scan he did of a dirt bike; the scan took about a minute and provides a lot of highly valuable information that would otherwise be very difficult to get. This looks promising for his next project. 😊

Do you have an interesting story or project to share? Contact us, who knows, it might end up on this blog as well!

Why should you pay more for a professional 3D scanner?

Why should you pay more for a professional 3D scanner?

You made up your mind and decided that 3D scanning was what you needed for your application. That’s a good start! It’s now time to choose which solution is most adapted to your needs. Shopping around, you may be tempted to consider more affordable 3D scanners. A lot of users online are promoting that there are some “very good” scanners available for $500-$600. Why would you even consider equipment that is 10x the price? Here are a few things to keep in mind when selecting a 3D scanning solution.

It’s all about the details!

Although Kinect-like 3D scanners usually have impressive capabilities when it comes to capturing data, they are rather limited when it comes to resolution (the amount of detail they will capture). Scanned objects and surfaces will often look quite smoothed out with round edges:

Transmission casing scanned with peel 3dTransmission casing scanned with  Skanect

Figure 1: Transmission casing scanned with peel 3d (top) and with Skanect (bottom)
More resolution means a crispier, more realistic scan where smaller features will be more precisely defined and more usable.

 

Is it accurate?

Even if a 3D scan looks nice, one should also consider how close it is to the actual model. The quality of the internal components, combined with software calibration, will have dramatic impact on the accuracy you can reach. Important errors are more than common on a low-cost scanner as can be seen in the below chart:
Accuracy comparison between peel 3d and Skanect
Chart 1: Accuracy comparison between peel 3d and Skanect
In this test, we scanned a controlled artifact 5 times with each 3D scanner, extracted the reference distance (point-to-point distance between two spheres), and compared it to the controlled measurement. As can be seen above, a Skanect 3D scanner resulted in an average error of 10.7 mm, while peel 3d provided an average error of 0.115 mm. The standard deviation is also significantly smaller with the peel 3d scanner.
This basically means that even if a shape is recognizable when scanned with a Skanect, it can be way off when if comes to how close it is to the actual object. In other words, if you are trying to design something based on your scan, chances are it will not fit (or be very loose).

Like aiming with a loose cannon!

There is also the notion of how repeatable an error is. Some measurement devices will not necessarily be accurate but at least afford good repeatability. For instance, think of a system that would provide an incorrect scale factor in a very consistent manner. All measures would be off—but always by the same amount (more or less). It’s not great but at least it can be compensated in some way…
Unfortunately, this is not the case of low-end scanners, especially when it comes to complex shapes, as can be seen below. The error is randomly spread over the scanned model in an inconsistent pattern:

Measurement error on 3 scan sessions made with a Skanect scannerMeasurement error on 3 scan sessions made with a Skanect scannerMeasurement error on 3 scan sessions made with a Skanect scanner

Figure 2: Measurement error on 3 scan sessions made with a Skanect scanner (warmer colours = positive errors, cooler colours = negative errors)

In this test, we compared the scan results made with a Skanect on a controlled mannequin head. As can be seen, despite following consistent measurement technique, the errors were significant and random, sometimes exceeding and sometimes short of the reference shape by several mm.


This basically means that your different scans will have significant measurement differences from one scan to another—even if you scan the same object, with the same technique and in the same environment! The results you get will basically be random within an important range.

Things you can do with your data…

Using a 3D scanner also usually involves at least a few post-treatment steps. For instance, you will likely need to remove surrounding surfaces (to isolate your object). Moreover, you will likely need to fill areas you couldn’t scan, re-align and perform your scan again, etc. The tools included in very affordable 3D scanners are usually quite limited, rudimentary and rather unstable.


Data finalization is essentially to 3D scanning what putting is to golf; it’s half the game and you can’t really neglect one vs the other. This means that if you plan to use your low-cost 3D scanning data, chances are you will need to invest in additional software (i.e. add significant cost to your solution).

Almighty targets!

Finally, trying to scan something flat or smooth (a car door for instance) will certainly be very challenging with low-cost scanners as they generally only rely on geometry for positioning; these items barely provide any geometry information to grab onto. This means you might wind up with very poor-quality (even unusable) results.


Stick-on markers will on the other hand ensure the accuracy of your 3D scanner and let you accurately scan the flat or smooth surface, making it fully usable in your application!

In the end…

Low-cost 3D scanners are not bad at all: they are actually a nice place to start with and get familiar with 3D scanning. If you are a hobbyist and interested in starting 3D scanning for fun, this could be a good place to start with. Affordable scanners may even be suitable for your specific application. However, if you are working in a professional environment, on commercial applications, a professional and comprehensive 3D scanning solution is best.