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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.

How to add an LCD screen to your peel 3d scanner

How to add an LCD screen to your peel 3d scanner

3D scanning applications are vast and so a user could be interested in scanning about any existing object. Whether you are scanning for reverse engineering or simply for the purpose of 3D archiving, it might not always be easy to keep your eyes on a laptop screen when scanning to see what you are doing. If you are working on a larger object or setup, you might have to move around as you scan. There is always a way to watch your laptop (for instance, you can move your laptop and play with the screen angle as you walk around your subject) but if you are amongst the people who prefer keeping their eyes on their scanner, did you know you can turn your phone into a remote display?

Using a simple app called Splashtop, you can replicate the image shown on your computer onto your phone via wireless network. With the app, you can hold your scanner in one hand, your phone in the other and scan like never before! The app can even make use of your phone tactile screen, so you can use click the software buttons using your fingers. While this feature would not be ideal to perform a full post-treatment process on your scan, it is great to perform simple tasks, such as starting/stopping a scan, without having to go back to your computer!

But wait, there’s more! Perhaps you would even prefer to keep your second hand free (to hold your coffee mug, for example). Turns out there is a solution to do this as well. You can purchase a curved mount directly from GoPro web store:

GoPro stick on mounts as purchased from their website

You can then combine the adhesive mount with the following material (purchased online from Amazon) to get an adjustable, removable screen holder:

When assembled, this is what it looks like:

Here is the result, when being used:

And there you have it: a fully interactive, adjustable and wireless remote display on your peel 3d scanner for under $50. It works like a charm and is dirt cheap! Enjoy!

7 things you should know about photogrammetry vs 3D scanning

7 things you should know about photogrammetry vs 3D scanning

Why pay for something when you can do it for free (or more affordably)?

Of course, nothing is entirely free. Even if you are using free photogrammetry software, you probably still need to invest in a camera to take the pictures. And the question remains: why would you pay for something if there is a solution that lets you do it for essentially free? It really depends what you want or need!

Here are the top 7 things you need to consider when trying to decide between photogrammetry and 3D scanning.

1. The all-forgiving textures

A high-resolution texture can sometimes have a very positive effect on the perception of a mesh. This is, for instance. how the cinematic industry works (very high textures with relatively low poly meshes). High resolutions work great for visual applications. If you are working on reverse engineering or plan to send your scan to a 3D printer, however, chances are you will want all the mesh resolution you can get. Take this colored mesh for instance. It looks great with texture, but it is actually pretty limited in terms of geometry.

Example of Texture before using 3d scanner

Example of Geometry using 3d scanner

2. Hold still, very still!

Another limitation for photogrammetry is that it requires the subject to be perfectly still. This is the reason why full body scanners require 20-30 cameras synchronized. Any slight movement will have devastating effect of the results:
Example of loop closure when using 3d scanner
Again, it is possible to achieve amazing results with a complete rig, but this can be a costly and bulky solution.

3D scanning, on the other hand, is a lot less affected by movement as it only relies on a smaller area at the time. A handheld device also has a significantly smaller form factor, making it much easier to carry it and bring it directly onsite.

3. What’s the deal with texture?

When working with photogrammetry, you take a lot of pictures of the same objects from different angles. The software then identifies features (found in the texture) and matches them in the different pictures. Being able to match these features between images from different angles is what makes the 3D surfaces. This works very well on an object with a lot of texture (like a rock)—but will produce very poor results on an object with little texture (like a car door).

A 3D scanner works better with objects with little texture as it relies on recognizing its projected pattern. Texture might disturb detection of the light pattern making it more difficult for the scanner to work.

4. Like working with a blindfold…

Another great advantage of using a 3D scanner is to see what you are doing in real time. This lets you see the areas you’ve scanned and, more importantly, the areas you’ve missed.

It is always possible to add more images to a photoscan, but you will need to process the whole model every time to know and see if you have everything you need. Processing large scans with a lot of pictures can take a long time. This also makes the use of 3D scanning as process significantly faster than using photogrammetry.

5. What kind of accuracy can you expect?

It is possible to obtain great looking scans with photogrammetry—but getting good accuracy is more challenging and more random as a lot of parameters are simply not controlled. Cameras (even the good ones) are generally not optically calibrated for the purpose of 3D scanning. This can create important scaling errors in a 3D scan.

3D scanners (the good ones at least) will generally be calibrated for the purpose of scanning. They provide more of a controlled ecosystem making them more predictable hence the possibility to provide accuracy specifications.

6. The difference between interior and exterior…

Again, photogrammetry works great if you can get all around the subject and take a good number of pictures, but what if you are trying to scan the interior of something in more of a confined area? Think of trying to scan the inside of a car for instance. Getting the right number of pictures of all components from all angles will be nearly impossible making it practically unfeasible to scan the inside of object with this technology.

This is where having a 3D scanner with a small form factor will definitely be handy. As you can easily get it into, around or under things, scanning objects from all angles will be a lot more achievable.

7. How much time can you invest in onboarding and training?

This is something you hear a lot: “Oh, the things he can do with his equipment!” Many people have the preconceived notion of being competent or qualified with a device or system. This is a system that relies on its user to deliver great performance. When you know how to use it, it works pretty well. However, getting there can sometimes be painful. And if the system is to be used by more than one person, these new users also have to learn how all of its ins and outs.

A system that does not require any training or specific scanning knowledge is, therefore, a great bet. This is the case with good 3D scanners as they will prevent users from collecting bad-quality data and deliver great performances regardless of the way they are used.

Overall, when choosing between photogrammetry and 3D scanning, you really have to consider your needs and applications. In some cases, and for some applications, photogrammetry is definitely interesting but, just like about anything, it is not suited for everything.