A Brief Analysis on the Application of 360-degree Panoramic Camera Technology

Abstract: In the past, when we tried to build a monitoring system in a small space, we would adopt several solutions: short-focal-length lens camera, adjusting the installation position, or multiple cameras linked to each other. However, the above methods all have different application defects; when choosing a short-focal-length lens camera, the horizontal visual range is less than 80 degrees (the wide angle does not exceed 90 degrees), so the monitoring range is small; adjusting the installation position is often restricted by the objective environment and affects the stable installation (for example, one side is glass, the other side is a door, there are wires on the top or a decorative ceiling that cannot bear weight, etc.); choosing multiple cameras linked to each other...

In the past, when we tried to build a monitoring system in a small space, we would adopt several solutions: short-focal-length lens camera, adjusting the installation position, or multiple cameras linked to each other, etc. However, the above methods all have different application defects; when choosing a short-focal-length lens camera, the horizontal visual range is less than 80 degrees (the wide angle does not exceed 90 degrees), so the monitoring range is small; adjusting the installation position is often restricted by the objective environment and affects the stable installation (for example, one side is glass, the other side is a door, there are wires on the top, or the decorative ceiling cannot bear weight, etc.); choosing multiple cameras linked to each other not only increases the cost of equipment investment, but also makes the construction more cumbersome.

Therefore, usually only when it is necessary, we try to install video surveillance equipment in a small space with great effort. Just when people are beginning to get used to such installation (due to the inherent contradiction of needs), a new force is quietly generated - 360-degree panoramic camera.

1. Technical Introduction

As the name implies, 360-degree panoramic video captures all image information from front, back, left, and right at once, without post-synthesis or multiple-lens stitching. Its principle is based on bionics (fisheye structure as shown in Figure 1) and uses the spherical mirror transmission and reflection principle of physical optics to image 360 ​​degrees horizontally and 180 degrees vertically at once (as shown in Figure 2), and then uses the software that comes with the hardware to convert it, presenting the picture in a way that the human eye is accustomed to.

Figure 1 Fisheye structure

Figure 2 Hardware diagram of fisheye lens

Fisheye lens is a special ultra-wide-angle lens, and its visual effect is similar to that of a fish eye observing the scenery on the water surface. The structure of fish eyes is similar to that of human eyes, but compared with the flat round lens of human eyes, the lens of fish eyes is spherical. Although it can only see relatively close objects, it has a wider viewing angle.

In Figure 3, the human eye looks at the real object in the water. Since the light reflected by the real object is refracted in the water, people mistakenly think that the object is in the position of the virtual image (for example, the phenomenon of chopsticks bending in the water). According to the principle of refraction, when light is incident from the air to water or other media, the refraction angle is smaller than the incident angle; when light is incident from water or other media to the air, the refraction angle is larger than the incident angle. It can also be summarized that when light is incident from one medium to another, the propagation direction generally changes. The fisheye lens is developed and manufactured based on the principle of refraction, with a larger spherical curvature (similar to the spherical lens of the fish eye) and the imaging plane is closer to the lens (the lens of the fish eye is very close to the retina).

[page]

Generally speaking, the shorter the focal length, the larger the viewing angle, and the larger the viewing angle, the stronger the distortion caused by optical principles. In order to achieve a super-large viewing angle of 360 degrees horizontally and 180 degrees vertically, the fisheye lens allows barrel distortion to exist reasonably. Except for the scene in the center of the picture, other scenes that should be horizontal or vertical have undergone corresponding changes. In order to convert the distorted image into a normal image suitable for human eyes to watch, it is necessary to use software to transform the image coordinates and perform image correction and other processing.

Figure 4 takes the Japanese FXC fisheye lens as an example to briefly introduce the basic process of 360 camera software processing:

360-degree panoramic image Convert coordinates and perform image enhancement processing Capture some information

Figure 4 Software Processing Flow

Figure 5 shows the principle and equation used to convert a circular image into a flat image in Japan's FXC360 panoramic processing system. Through computational processing in PC software or embedded processing systems, a flat image that the human eye is accustomed to is presented.

Figure 5 Equations used by software processing

2. Product features of 360-degree camera

1. Overwhelmingly wide-angle photography

Horizontal 360 degrees, vertical 180 degrees panoramic camera, subverts the concept of wide-angle camera. For 360-degree products,

Video surveillance has no blind spots.

Figure 6 General camera viewing angle

Figure 7 360-degree camera viewing angle

[page]

2. Spherical images can be transformed into normal plane views

The image captured by the fisheye camera can be converted into a normal plane view suitable for the human eye after correction and image expansion by the camera's internal software.

Figure 8 Plane expansion real scene

3. Reduce costs.

Compared with the traditional camera video surveillance system, the use of 360-degree cameras with all-round viewing can effectively reduce the number of cameras and reduce the investment in multi-input hard disk recorders. It can also reduce the difficulty of construction wiring and save subsequent maintenance costs.

4. Can be connected to the existing video surveillance system

The 360-degree camera can be seamlessly connected to the existing analog monitoring system, and has good scalability. It can be connected to an ordinary hard disk recorder using a copper axis cable to achieve 360-degree panoramic monitoring.

Three application cases

360-degree panoramic cameras can be widely used in building lobbies, entrances and exits, elevators, conference rooms, restaurants, parking lots, factory workshops and many other places. The following is a monitoring example using 360-degree panoramic camera equipment.

Application in a narrow bus compartment (as shown in Figure 9 and Figure 10). This case uses a 360-degree panoramic camera from Japan's FXC, installed in the middle of the compartment, to achieve panoramic video monitoring without blind spots with only one device. If traditional camera monitoring is used, a compartment would require about four devices to cover the entire range, which would destroy the aesthetics in a narrow space and easily cause discomfort to passengers.

Figure 9 Spherical imaging inside the car

Figure 10: In-car imaging expansion

[page]

Application in a company's meeting room (as shown in Figure 11). In this case, combined with audio and video recording equipment, 360-degree panoramic camera technology is used to record the entire meeting with only one device. The recorded data is uploaded to the server for future review or for relevant authorized personnel to read. This system of Japan FXC Co., Ltd. is the ultimate device in the meeting recording industry.

Figure 11 Three visual processing in the conference room (original image, binary image, and quadrupled image)

As shown in the above example, 360-degree panoramic camera can capture the surrounding environment. It can be used in small spaces to eliminate dead angles and blind spots. If the overall size is not taken into consideration, according to the existing 2.8mm (75-degree) wide-angle camera combination on the market, to achieve the field of view of a 360-degree "panoramic" camera, {(360 ÷ 75 ≈ 5) + (180 ÷ 75 ≈ 2)} ≈ 7 units are required.

Four other features

In addition to the above features, the 360-degree panoramic unique virtual PTZ technology (as shown in Figure 11) allows you to experience operations such as Zoom In/Out and rotation when playing back images, which can completely replace the motor-driven PTZ control system in traditional high-speed ball cameras. With the technical foundation of virtual PTZ, on the one hand, it will be easier to realize virtual reality; on the other hand, it will reduce mechanical motor components, reduce equipment power consumption and heat generation to a greater extent, reduce component friction loss, and extend the service life of equipment and systems.

With the use of 360-degree panoramic cameras, there is a new solution for video surveillance systems in small spaces, which can solve multiple problems such as viewing distance, viewing angle, installation, and cost control.

Figure 12 Example of virtual PTZ operation of Japanese FXC camera

Conclusion

360-degree panoramic view can truly and quickly display all the image information of the scene within 360 degrees, which can give viewers an immersive feeling. It has obvious advantages in many application scenarios. In addition to the monitoring industry, it can also play a huge role in product display, video teaching, audio-visual entertainment, virtual reality, etc. I believe that this image technology will be applied to various industries in the near future.