3D scanning - what is it?

What Is 3D Scanning?

3D scanning is a measurement technique that allows you to obtain a three-dimensional model of a physical object. This process is possible thanks to the use of 3D scanners, which measure the distance between the surface of the object and the measuring device, collecting hundreds or even thousands of points. These points are then processed to create a three-dimensional model that faithfully reproduces the shape and structure of the original. It is a process that has applications in various fields, from industry to medicine, opening the door to new possibilities for design, production and exploration. To understand the full scope of 3D scanning, it is worth looking at its basic aspects.

3D scanning methods

3D scanning, a key technology in the field of visualization and production, is constantly evolving, introducing new methods and techniques. Below is an overview of the most modern 3D scanning methods that shape the present and future of this fascinating field:

• Laser scanning

One ​​of the most widely used methods is laser scanning. The laser scanning method is a non-contact method that involves the optical measurement of three-dimensional objects. This method uses laser light as an information carrier. The technology works by measuring the distance and angle between the scanning device and the model being examined. The reflected laser light from the object being examined allows the determination of the coordinates of the point [x, y, z], which create the so-called point cloud. At the same time, when determining the coordinates, the intensity coefficient of the light signal reflection can also be determined. The measurement is carried out automatically and allows for obtaining a large amount of data in a short time. The obtained point cloud consists of several million or even billions of individual points taken by the scanner from the object. This precision means that the laser scanning method is used, among others, in industry for designing and reproducing elements and for checking the dimensions of an existing detail by comparing the base model to a 3D scan.

• Structured light scanning

The principle of operation of structured light scanners is to project a systematic pattern in the RGB or NIR spectral range onto the scanned object. In a typical structured lighting system, the projector works with one or two cameras that collect an image of the scanned object. The pattern of light that falls on the object usually consists of a series of stripes, but sometimes it occurs as a set of dots or other shapes. The camera system analyzes changes in shape, which allows for the reconstruction of a three-dimensional model. This method can be extended to include color imaging when using a color detector. 3D scanners based on structured light technology operate over short distances when measuring the 3D geometry of objects up to 3m and can be mobile, i.e. held in the hand, or stationary, i.e. mounted on a tripod and using a rotary table. The condition for using this method is to determine whether the surface of the tested object is scattering or only partially scattering light, because structured light scanners are sensitive to the lighting conditions in a given environment and surroundings. Working outdoors with such a scanner can be extremely difficult, and in some cases impossible.

• Photogrammetry

Photogrammetry is based on the analysis of photographs of an object from different angles in order to recreate a three-dimensional model. The reproduction of an object in three dimensions is done by taking a series of two-dimensional photographs, where each of the photographs was taken at a different angle relative to the others. The photographs are taken with a camera or scanner with known optical reproduction parameters, the so-called calibrated detector. Calibration of the detection device allows the coordinates of the recorded images to be assigned to simple equations located behind the device with the optical system. Individual points of the object are found after recording a set of measurement photos. The software, based on the detected points, which have their coordinates, connects them using algorithms into a point cloud. Then, using the acquired point cloud, accurate 3D models are generated. Models created using photogrammetry are characterized by a certain accuracy, which results from the data processing procedures and equipment used, such as: the shooting distance and the focal length of the camera lens and knowledge of the camera characteristics. Photogrammetry is commonly used to build 3D models of large objects (monuments, buildings, etc.) as well as in geodesy, cartography and in film and video game production.

• Computed Tomography (CT)

Computed tomography (CT) is an advanced imaging technology, the use of which is not limited to medicine. In industry, CT plays a key role in quality control and precise analysis of the internal structure of various objects. In addition, it is widely used in the field of metrology, enabling precise geometric measurements. An industrial CT scanner works on a similar principle to its medical counterpart. The basic element is an X-ray source and a detector, placed on opposite sides of the examined object. During scanning, the source emits X-ray radiation, which passes through the object and reaches the detector. The X-ray beam generated by the X-ray tube has the shape of a cone, which allows the projection of the X-rayed object onto a flat, digital detector. The examined element rotates around its own axis by a given angle, and a digital image is taken at each position. The detectors record the amount of radiation passing through individual areas of the examined object. This data is then transferred to a computer, which uses advanced tomographic reconstruction algorithms. This process generates a three-dimensional image of the internal structure of the object, enabling precise analysis. The accuracy and quality of the obtained data is determined by the distance of the examined object from the X-ray tube and the number of images taken.

3D scanning process - step by step

The 3D scanning process takes a few steps, and its detailed description may vary depending on the technology used. Below is a general step by step guide:

1. Selecting the Scanning Technology:

Selection of the appropriate 3D scanning technology, such as laser scanning, structured light, photogrammetry or CT.

2. Preparing the Object:

• The object should be cleaned of any contamination to obtain a more accurate 3D scan.

• If the object has a shiny surface, consider using contrasting substances (depending on the selected 3D scanning technology).

• If the object is large enough, reference points, so-called markers, should be glued on it. If the object is small, reference points must be glued near it.

3. Scanner Settings:

Configure scanning parameters, such as resolution, measurement area size, and others depending on the specific technology.

4. Calibration:

The scanner must be calibrated to ensure accurate measurements.

5. Start Scanning:

The next step is to start the scanner and collect data from the object's surface.

6. Data reading and processing:

The collected data is transformed into a three-dimensional point cloud representing the surface of the object.

7. Creating a 3D model:

Based on the point cloud, computer algorithms generate a three-dimensional model of the object.

8. Editing and corrections:

When necessary, the model is edited to remove artifacts created during scanning or to adjust details.

9. Texturization (optional):

Adding texture based on photos of the object if the scanner did not record colors.

10. Export model:

Export the finished 3D model to a selected file format, such as STL, OBJ, etc.

11. Assessing the accuracy and quality of the 3D scan:

Visually assess the accuracy and quality of the obtained model compared to the real object.

12. Further Processing (optional):

If necessary, additional processing steps such as triangle reduction or geometry optimization are performed.

Challenges and future of 3D scanning

• New Scanning Technologies

The future of 3D scanning will certainly be related to the development of new technologies. The use of advanced sensors, such as lidars or higher resolution cameras, will allow for even more precise recording of shapes and textures. Integrating photogrammetry technology with artificial intelligence will enable automatic correction of scanning errors, which will significantly improve the process.

• Application in medicine

The future of this technology in medicine holds great potential. 3D scanning is already being used to create custom prostheses and implants, which will significantly improve the effectiveness and safety of surgical procedures.

• Custom production

In industry, 3D scanning will contribute to a revolution in custom production. 3D printing will become even more precise thanks to the scanning of accurate models of objects. Companies will be able to quickly adapt to changing market needs, producing personalized solutions with minimal cost and waste.

• Development of Virtual Reality (VR)

Integrating 3D scanning with virtual reality technology will open up new possibilities in the field of visualization. Users will be able to walk through virtual models of scanned objects, which will find applications in, among others, in architectural design or exploration of space before the actual implementation of the project.

3D scanning is not just a tool, but a real gateway to the digital world of three-dimensional representations. Its applications are extensive, and the development of this technology promises an even more fascinating future. From complex industrial structures to delicate works of art, 3D scanning opens up new horizons of possibilities for digital modeling of reality.