1. What is a fisheye camera
A fish-eye camera is a camera equipped with a fish-eye lens. The fish-eye lens is a special lens with an ultra-wide angle. Its structure is modeled after fish-eye imaging, and it is a camera that can realize large-scale non-dead-angle monitoring independently. We know that fish eyes are similar in structure to human eyes, but their crystals are spherical and human eyes are oblate. Although fish can only see objects closer, they have a wider angle of view. Up to 180 °; the fisheye camera with the same characteristics is installed through the ceiling, the visible range can reach 360 °, and it can monitor all objects in a large-scale scene, so it is also called a panoramic camera.
Figure 1 Fisheye 
Figure 2 Fisheye lens
2. Difficulties in fisheye camera technology
Serious optical distortion: The fish-eye camera has an ultra-wide angle, which enables comprehensive monitoring of a wide range of scenes with a small number of devices. But relatively, the excessively large viewing angle brings more serious optical distortion (the picture is even round), and the image distortion is more serious; the device needs to correct the original image before its effect will be accepted by the user.
Insufficient detail performance: large scene monitoring and a small focal length and depth of field cause the fisheye camera to see the distant scene not very clearly. To this end, engineers need to use high-resolution sensors to ensure that the target object has more pixels to express; at the same time, the performance of the fisheye lens is improved as much as possible, and the depth of field range is better than that of the traditional camera, so as to improve the clarity of objects farther away degree.
Figure 3 Fisheye lens imaging diagram
3. Introduction of Hikvision products
Fish-eye cameras are generally divided into ordinary shotguns + fish-eye dedicated lenses and integrated hemispherical fish-eye cameras. Hikvision independently developed and launched the 12 million hemispheric fisheye camera DS-2CD63C2F-IVS. The device can output real-time images with 3072 X 3072 resolution and IP66 structure. Its main technical parameters are as follows:
Figure 4 DS-2CD63C2F-IVS 12-megapixel fisheye camera
Ø Support digital wide dynamic, 3D digital noise reduction function
Ø High-efficiency infrared lamp, long service life, 360-degree omnidirectional fill light, irradiation distance up to 15 meters
Ø Support up to 128G Micro SD / SDHC / SDXC card local storage
Ø ICR infrared filter type automatic switching, to achieve true day and night monitoring
Ø Built-in microphone and speaker, support two-way voice
Ø Super wide-angle lens can be used to shoot 360 ° surround view, realizing no blind spot monitoring
Ø Support hardware to correct panoramic or partial picture, after correction, the video stream can be directly output for preview or recording.
Ø Support correction of panoramic or partial images, support three output modes
Ø Support cross-border detection, regional intrusion detection, and alarm linked dome camera
Ø Support output of fisheye heat map
Ø Support up to 20 simultaneous access
Ø With a variety of white balance modes, suitable for various scene needs
Ø Support backlight compensation, automatic electronic shutter function, adapt to different monitoring environments
Ø IP66, anti-riot: anti-riot level supports IK10
The above parameters have created Hikvision's 12 million hemisphere fisheye camera products with unique characteristics, as follows:
Two-way intercom: The device has a built-in microphone and speaker, which can realize two-way voice intercom without external equipment.
Infrared fill light: with three high-efficiency infrared lights, each light is responsible for 120 ° fill light, to achieve 360 ​​° all-round infrared fill light.
Output after hardware correction: The traditional fisheye equipment stores the video as the original distorted image. When viewing the video, you need to use a special decoder or related software to correct the video before viewing; DS-2CD63C2F-IVS fisheye camera can realize the correction of the original image Re-output the data, the user can plan multiple channels and formulate the corresponding monitoring area to output independently, the stored and transmitted data is the corrected image; so that the user can selectively view the corresponding channel according to the need, without having to obtain all the original images, saving Communication bandwidth and storage space.
As shown in Figure 5, the upper right corner is the original image. The user can select three areas on the image as independent monitoring areas. The fisheye device will correct the image distortion in this area and output image data separately; the user can selectively obtain Preview and store images in any specified area.
Figure 5 Example of fisheye correction
Rich intelligent functions: DS-2CD63C2F-IVS has intelligent detection functions such as cross-border detection, regional intrusion, etc., and also has a scene heat map display. In this mode, the device can analyze, statistics, and report regularly on the aggregation of people in the scene. It is convenient for users to analyze the hot areas in the scene, which can be applied in shopping malls, supermarkets, museums, counters and other scenes.
In addition, the device can also be linked with intelligent high-definition network dome cameras to realize the combination of "point" and "face" monitoring. "Face" refers to the large picture taken by the panoramic camera, "point" refers to the details of the high-speed ball to the panoramic big picture, and the dome can automatically track multiple targets in the panoramic picture, so as to achieve "no blind spots, no dead ends". Non-stop orientation monitoring. As shown in Fig. 6, after the target pedestrian triggers the detection line, the ball player will automatically track to the trigger area to track the target object until the target walks out of the monitoring area to realize the multi-target alarm rotation training tracking.
Figure 6 Fisheye-ball machine linkage detection
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