The current status and future development trend of panoramic cameras

The development of network cameras has basically met the needs of “high definition”, “day and night monitoring” and “long distance monitoring”. However, with the development of market segments, the demand for super wide-angle cameras has gradually emerged. Mainly used in large open areas such as conference rooms, offices, halls/lobby, shopping malls, warehouses, workshops, etc., to solve the problem of covering the area by using several cameras, or using the fast ball to cruise back and forth to achieve scene coverage. Dead angle monitoring. Therefore, the panoramic camera came into being. This paper mainly discusses the application and development of the panoramic camera.

Panoramic camera classification

At present, there is no clear definition of the panoramic camera in the industry. For a camera that can be seen more widely and at a larger angle, everyone calls it a panoramic camera. A narrowly defined panoramic camera is a camera that can achieve 360° monitoring.

At present, the product form of the panoramic camera includes a multi-lens type, a single fisheye lens type, and a hybrid type.

Single fisheye lens:

The use of a gun camera or a dome camera plus a fisheye lens is the simplest and most economical way to achieve panoramic surveillance. The key point of this approach is that the camera itself has the ability to correct the distortion of the fisheye. Or you can use a special processing software to correct the image after deformation of the fisheye lens.

Multi-lens type:

The multi-lens multi-angle monitoring and splicing image realizes 360-degree monitoring. This method is very complicated and costly, but it lacks the fisheye distortion caused by the fisheye panoramic camera.

mixed type:

It adopts the PTZ dome camera and the fisheye lens. This method is rare. The camera can be used as a dome camera when it rotates. When the dome camera and the fisheye lens overlap, it can be used as a panoramic camera.

Key technology point

First, the quality of the camera will greatly affect the quality of the surveillance image. In the strict sense, the focal length of the panoramic camera lens is about 1.9mm, the viewing angle range can reach 180°, and the effective pixel can reach 12 million pixels or higher. It is much higher than traditional cameras. The ordinary super wide-angle lens (the viewing angle range is about 130°) has a small difference between the intermediate field of view and the panoramic camera, but the edge definition and the effective monitoring distance are far apart.

Second, the choice of image sensor affects the effect of the monitored image. Due to the wide monitoring range of the panoramic camera, the scene is more complicated than the single monitoring scene. The information amount of the image sensor is inevitably huge. The resolution of the image sensor and the sensitivity are greatly affected by the image effect. At the same time, the wide dynamic effects of different specifications of the sensor are not the same, which is an important indicator to measure the quality of the panoramic camera.

Thirdly, the panoramic camera using the fisheye lens has different imaging principle than the ordinary camera. The edge of the image tends to form a convex and deformed image, so it is easier to make the image distorted or distorted than the ordinary camera, which affects the image quality. So how to correct and restore the image and see the monitoring objects in the image is the most important problem of the panoramic camera. At present, there are two technologies that can correct distortion: one is to process information and restore image by the back-end platform; the other is to directly correct the built-in software of the camera and then transmit it to the monitoring back end.

Fourth, the virtual PTZ can be used to zoom in and out of the stored images for detailed observation. In the field of security monitoring, PTZ controls the pan-tilt up and down rotation and the lens to focus, for automatic or manual tracking of the locked target, and tracking the target in the monitoring range. The virtual PTZ used by the panoramic camera has the application concept similar to that of the pan/tilt. It does not have to perform the actual mechanized rotation like the real pan/tilt, but achieves similar effects by scaling the image, thus greatly increasing the monitoring system. The service life makes it easier for the monitor to operate and reduce maintenance costs.

Development status of panoramic camera

The panoramic camera has been developed for more than ten years. Although it has great difficulties in key technologies such as lens correction and virtual PTZ, some manufacturers have launched panoramic camera products and widely promoted and guided by consumers. We don't discuss the effects of panoramic cameras from various manufacturers. From the practical point of view, the market share of panoramic cameras seems to be “poor”.

Compared with traditional surveillance cameras, the most prominent advantage of panoramic cameras is the 360° surveillance angle, which largely compensates for the range of viewing angles that can be achieved by multiple conventional cameras. However, the expansion of the field of view is based on the sacrifice of monitoring distance. cost. At present, the panoramic camera is mainly used in outdoor open-view places, such as road traffic, open-air plazas, residential buildings, port terminals, etc. The monitoring width of some places is even more than 100 meters. It is impossible to see the panoramic images to achieve scheduling. No energy to see the details of the face, vehicle license and so on.

From a cost point of view, the cost of a panoramic camera is often 5 to 10 times that of a conventional camera, which is difficult for most engineers or end users to accept. After all, the network camera has developed to the present level and has become a cabbage. price". In actual use, a large number of flexible point deployments can not only solve the full coverage of the scene, but also clearly monitor the key scenes. This makes the significance of the panoramic camera's control in the actual project to a large extent greater than the actual use meaning, resulting in the final user must pay for its high price.

The development trend of panoramic cameras

The development of panoramic cameras has been more than ten years, and the real promotion has only started in the past two years. Specifically, the development trend of panoramic cameras is as follows:

1, industry applications are the main battlefield of panoramic cameras. Although the panoramic camera is more suitable for places with small space and simple monitoring environment, such as retail stores, small shopping malls, elevators, parking lots and conference rooms, and so on. However, due to its high price, complicated image processing technology and low resolution after image correction, the panoramic camera did not enter the public life like other ordinary cameras. The panoramic camera will be mainly used in the fields of finance and political law. This is mainly based on the special scenes of these two industries, which require a wide range of perspective coverage, and the use value is far greater than the cost pressure.

2, high resolution. At present, the resolution of panoramic cameras produced by mainstream equipment manufacturers is about 3 million and 5 million. However, considering the resolution density, the same pixel camera will cause pixel dispersion and degradation when monitoring a larger area. This is because the monitoring range is very large. On the imaging chip of the same size as the conventional monitoring lens, it is necessary to receive several times of image information, which results in a decrease in the resolution of the picture. Therefore, only the quality of the image of the monitoring image is not required. Can be used when high or when using high resolution imaging devices. Therefore, for panoramic cameras, improving screen resolution is an important research topic in the future. Future panoramic cameras can distinguish at least 4K or even 12 million pixels, which makes more sense.

3, H.265 coding. High resolution will inevitably lead to an increase in bandwidth and storage pressure. At present, the mainstream H.264 encoded 4K resolution code stream is about 16~32Mbps, which is the actual network bandwidth environment or the cost pressure of end users. hard to accept. Therefore, the higher compression ratio coding method makes the high-resolution appeal become practical, and the key to solve this problem is H.265 coding. According to the actual test and analysis, the same scene H.265 saves more than half of the H.264 encoding bandwidth. At the same time, the image processing effect is also greatly improved, and the storage cost can be greatly saved. Therefore, the 265-encoded camera is obtained as soon as it is listed. A high level of attention and recognition. The panoramic camera will also gradually shift towards the H.265 encoding, which is the market driver.

4, wide dynamic. The panoramic camera monitors the entire scene with a fisheye lens with a 360-degree angle of view. Such a wide range of monitoring is bound to cause difficulties in the processing of white balance and exposure of the panoramic camera. It is because of this that the application of the panoramic camera in the room is limited. Solve the wide dynamic effect of the panoramic camera, which can promote the application of the future panoramic camera in the indoor environment.

5, smart. Intelligent analysis is particularly important based on the demand for industrial applications of panoramic cameras. Intelligentization is also a major direction in the development of security surveillance. However, the existing network camera intelligent analysis has the problems of low recognition rate and high false positive rate, which needs to be strengthened in the subsequent algorithm improvement. In addition, the types of intelligent analysis are not limited to entry-level intelligence such as virtual perimeter and squall line alarms, but should achieve breakthroughs in behavior analysis, audio and video anomaly detection, and traffic statistics.