Currently, there are four main types of 3D vision technologies on the market: binocular vision, TOF (Time of Flight), structured light 3D imaging, and laser triangulation.
Binocular Vision
Binocular technology is currently a widely used 3D vision system. Its principle is similar to our human eyes, using two viewpoints to observe the same scene to obtain perceptual images from different perspectives. Then, the parallax of the images is calculated using the principle of triangulation to obtain the three-dimensional information of the scene.
Due to its simple principle, binocular technology does not require special transmitters and receivers, and can obtain three-dimensional information under natural light. Therefore, binocular technology has the advantages of a simple system structure, flexible implementation, and low cost. It is suitable for online product inspection and quality control in manufacturing environments. However, the disadvantages of binocular technology are its complex algorithms, large computational requirements, and poor performance in low light or overexposed conditions.
3D Structured Light Technology
This technology projects a beam of structured light from a light source. This structured light is not ordinary light, but rather light with a specific structure (such as alternating black and white patterns) that is projected onto the surface of the object to be measured. Because objects have different shapes, these patterns or spots will undergo different deformations. Based on these deformations, algorithms can calculate distance, shape, size, and other information to obtain a three-dimensional image of the object.
Laser Triangulation Method
This method is based on the principle of optical triangulation, determining the three-dimensional coordinates of each point of a spatial object based on the geometric imaging relationship between the light source, the object, and the detector.
Typically, a laser is used as the light source and a CCD camera as the detector. It shares the advantages of structured light 3D vision: accuracy, speed, and low cost.
TOF (Time of Flight) Imaging Technology
TOF stands for Time Of Flight. Its principle involves continuously sending light pulses to the target object, and then using a sensor to receive the light reflected from the object. By detecting the flight time of the light pulses, the distance to the target object is determined.
The core components of TOF are the light source and the photosensitive receiving module. Because TOF directly outputs depth information based on a formula, without requiring algorithms similar to binocular vision, it has the characteristics of fast response, simple software, and long recognition distance. Furthermore, because it does not require the acquisition and analysis of grayscale images, it is not affected by external light sources or the surface properties of the object. A typical TOF 3D scanning system can measure the distance of 10,000 to 100,000 points on an object per second. However, the disadvantages of TOF technology are low resolution, inability to produce high-precision images, and high cost.
3D is poised to become mainstream
Robotics, autonomous driving, and financial payments have already demonstrated a strong demand for 3D vision. Of course, there's also the metaverse, where the integration of virtual and real worlds, AR, VR, and other XR devices and 3D interaction needs have already become prominent. These demands have created a huge market, but it is also an extremely fragmented market.
According to GGII data, the size of my country's machine vision market is expected to reach 20.86 billion yuan by 2023, with the 3D vision market reaching 3.428 billion yuan. By 2025, the size of my country's 3D vision market is expected to exceed 10 billion yuan. In this future multi-billion dollar market, 3D vision will tend towards intelligence, integration, real-time capabilities, high performance, and multi-scenario applications.
While 2D vision is currently mainstream, as measurement accuracy requirements increase and the conditions of the objects being measured become more complex, the shortcomings of 2D systems are becoming more pronounced. Meanwhile, 3D vision technology is constantly making breakthroughs, offering unparalleled advantages over 2D in terms of accuracy, flexibility, and speed. Therefore, 3D machine vision inspection has the potential to replace 2D systems, and it is believed that 3D vision will become the mainstream vision system in the future.