What is worth considering when choosing a 3D scanner?

More and more companies are deciding on buying their own 3D scanner. Nonetheless, choosing the right device, suited to one’s needs is not easy. The variety of devices is very wide. They differ with technologies and capabilities. Their price, depending on the manufacturer and parameters, may vary from several thousand to several hundred thousand euros.

What is worth considering when choosing a 3D scanner? We have provided a summary below to help you understand what you need to consider when buying a 3D scanner.

1. CHOOSING THE APPROPRIATE 3D SCANNING TECHNOLOGY – LASER LIGHT OR STRUCTURED? 

3D scanners use various 3D scanning technologies. The most popular are laser 3D scanners and structured light devices. The mechanism of collecting data from the environment used in the device is closely related to its capabilities and, consequently, to its subsequent use. Each technology has its own advantages but also limitations.

Structured light technology 

Structured light 3D scanners emit light in the form of lines that fall on the analyzed physical object. The position of the beam changes during the scan, collecting data on the analyzed element. The cameras installed in the device record and examine the line alignment, generating a digital model of the object. 

This type of technology has a high 3D scanning speed, and therefore can be used to generate 3D human models. They are lightweight devices and are characterized by a lower price than 3D laser scanners. Nevertheless, they are very sensitive to lighting conditions, all shadows on the object are reproduced on the generated 3D file. Therefore, using the 3D scanner for structured light outdoors or in difficult conditions (e.g. rooms with high dustiness) may be problematic. Additionally, black or glossy surfaces must be covered with a special spray before 3D scanning begins.

Laser technology 

The laser technology used in 3D scanners consists in analyzing the refraction of laser rays on the surface of the tested object or measuring the distance between a physical element and the device. The sensor or camera analyzes the obtained data and recreates the geometry of the object. 

Laser 3D scanners are characterized by a much higher precision and resolution of 3D scans compared to devices using structured light technology. They are capable of scanning in low light conditions as well as black, shiny and white elements without the need to coat them with matting spray. Additionally, laser 3D scanners can scan large objects (e.g. buildings). Nevertheless, they are usually much more expensive than structured light scanners, and at the same time have a lower scanning speed.

2. 3D SCANNER AND 3D MODELING SOFTWARE AVAILABILITY

Many 3D scanners available on the market have special software that allows you to operate the device, as well as the subsequent processing of the obtained models. When buying a 3D scanner, it is worth paying attention to the type and quality of the offered software, as well as its availability, as not every manufacturer offers compatible software. Therefore, before buying, make sure that it is included in the set.

Usually, before finalizing the purchase, a presentation of the device takes place. During the meeting it is worth testing not only the capabilities of the 3D scanner, but also the functions offered by the software. The programme should be intuitive and easy to use, it is desired to have additional features, such as the ability to clean scans from points, that are not a part of the project. The possibility to automatically optimize the files generated during the scanning is also a desired function. Documents, which are the size of several hundreds megabytes are hard in further processing, due to their large size. The file optimization option allows you to reduce the number of triangles while maintaining the model geometry. The smaller amount of data allows you to work with 3D files faster and more efficiently.

3. CAD modelling ability 

There exists a widespread belief that 3D scanners generate ready-to-use CAD files. It is fairly wrong. The device is designed to support the 3D design process, but does not create files ready for 3D printing or CNC machining. Each scan requires further processing and refinement of the project in a program designed for this purpose. Although 3D scanners allow you to save the downloaded geometry in STL format, the generated files usually require correction of imperfections, improvement of the model mesh, or optimization of the number of triangles. 

Moreover, while 3D printers can handle STL files very well, CNC milling machines handle CAD formats best. Therefore, the obtained models will need to be redesigned to this format in order to start the CNC machining process.

4. CAPACITY INDICATOR VALUE

When choosing a 3D scanner, you should not be guided only by the accuracy of the device. An important, and very often overlooked, precision parameter is the capacitive volume. While accuracy expresses the ability to accurately reproduce the details of a single scan, the capacitive error (capacitive volume) applies to the entire scanning process of large objects. This parameter allows you to determine how many millimeters lose precision for each meter of the scanned physical object. In general, the lower the value, the more precise the device is.

5. WORKING CONDITIONS OF THE 3D SCANNER

Working conditions of the 3D scanner are very important, not only due to the aforementioned limitations assigned to the technology, but also because of the time of scanning and possibility to perform the process. Main factors, which have negative influence on the 3D scanning are: 

• temperature – for most 3D scanners it is recommended to work in an ambient temperature in the range of 0-30 ℃ 
• humidity – high humidity may have a negative effect on the operation of the 3D scanner 
• vibration – unstable ground or a place with significant vibrations can affect the quality and duration of 3D scanning 
• lighting – poorly selected lighting can generate problems during 3D scanning. Color objects are best scanned under intense lighting. Nevertheless, too intense lighting may generate noise and measurement inaccuracies. Natural daylight on a cloudy day is the best choice, because then the light is evenly distributed over the entire surface of the object. 
• transparency and reflectivity of the scanned objects – in the case of objects that strongly reflect light or are transparent, it is necessary to use a matting spray

Of course, there exist 3D scanners which are not sensitive to the above factors, nevertheless it is worth making sure if the working environment of the device will be suitable for the chosen device. 

6. HARDWARE REQUIREMENTS FOR THE 3D SCANNER AND SOFTWARE 

As we mentioned before, the 3D scanner is not an autonomous device and requires cooperation with a computer. Therefore, before buying, it is worth checking whether your computer will be able to work with the selected 3D scanner model and compatible software.

7. SELECTION OF THE SCANNER TYPE FOR SCANNED OBJECTS

3D scanners can be divided into stationary, handheld and hybrid. Choosing the right type for the dimensions of the scanned objects is crucial. Stationary scanners are placed on a tripod or a measuring arm, therefore, when scanning large objects (e.g. buildings), they will generate mobility problems. Scanning large-size elements will require multiple rearrangements of the device during the process.

Handheld scanners are fully mobile devices, which are suitable for scanning the medium sized objects (e. g. cars). They are lightweight, so it is easy to hold the device in hand, even during the surface scanning. 

Hybrid scanners are a type of handheld devices, which can be positioned on a tripod or a rotary table, enabling stationary scanning. 

An important aspect is the weight of the device. Desktop scanners are typically heavier than handheld and hybrid scanners. Therefore, when scanning medium and large objects, we should choose scanners weighing no more than 1.5 kg. Larger elements mean longer measurement times. It should be translated into the need to hold and maneuver the device for up to several hours, often in uncomfortable positions.

Another aspect, which is worth considering is scan speed, which can be expressed as a number of points collected within a second. The higher this value, the more efficiently the device gathers and processes data from the environment. For objects with large and medium dimensions, this value should not be less than 350,000 points / s. Another thing to focus on is the need to calibrate the device, especially its frequency and duration. You can find out during the presentation of the device or by contacting the seller.

8. TECHNICAL SUPPORT AND INTRODUCTORY TRAINING 

Seller technical support and implementation training are very important issues when purchasing a 3D scanner. Nevertheless, this is not an option offered by all companies. Usually, when buying a device without technical support, the price is more attractive. Nevertheless, the time spent on implementing and learning how to operate the machine is not proportional to the difference in amount.

That is why choosing the seller, who offers introductory training and technical support along after the buying process. Without his help, implementation of the 3D scanner to the company may be difficult and time consuming. Moreover, in case of problems with the machine, we will not obtain specialist help. The implementation training should cover not only starting the device, but also the 3D scanning process and working with the software, i.e. all issues related to the operation of the machine.

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