One of the challenges associated with video system design has been matching camera field of view with the desired area of coverage, particularly in large open spaces such as sports facilities, airports, and large manufacturing facilities.
While the introduction of IP cameras has greatly increased the quality of both live and recorded images, the camera can only view or record images in the field of view. Historically, when faced with this challenge most video system designers would rely on a solution that included a combination of multiple fixed view cameras installed along with select pan tilt and zoom (PTZ) cameras with the intent to fill any blind spots in coverage. While that design strategy is still valid for some applications, the relatively recent introduction of high resolution panoramic cameras has changed the video system design landscape.
Usually, these cameras feature either a 360° or 180° field of view. 360° cameras are typically mounted at “ceiling” height and are pointed downward in the center of the area of interest to provide a 360° field of view. 180° cameras are typically wall mounted to provide coverage of areas to include exterior building facades, long corridors, large reception areas, etc. In either case, the cameras are capable of providing full fields of view with no blind spots.
The most common panoramic camera designs consist of either a single camera with a 180° or 360° extreme wide angle lens or multi-sensor cameras that include multiple camera sensors and lenses in a single enclosure. A 360° multi-sensor camera usually will consist of four camera sensors with 90° lenses on each sensor. One advantage to this type of camera design is that the individual images are not optically distorted. However, special software is required to “stitch” the images together to provide the full field of view. The single lens cameras provide a spherical “fish eye” type of image which is optically distorted and requires special software to “de-warp” the signal to create a corrected and usable image. Some single lens cameras are designed with de-warping capabilities built into the camera and some require special software to be installed as part of the video management system. Generally speaking, the multi-sensor cameras can be two to three times more expensive, but provide a higher resolution and quality image when compared to the single sensor, wide angle lens designs.
Applications and Trends
Panoramic cameras have a potential application in any market where omnidirectional monitoring of large open areas is a requirement. This can include retail stores, shopping malls, airports, parking lots, casinos, sports facilities, warehouses, seaports, manufacturing facilities and any other application where it is important to provide a high degree of situational awareness by continuously monitoring people as they enter and move throughout an area of interest. The introduction of panoramic cameras has provided end users with the potential of covering larger areas of interest with fewer cameras while reducing overall costs for the cameras, camera power and maintenance.
When looking to deploy a panoramic camera, many options should be taken into consideration. Paying very close attention to the details of the surrounding conditions, e.g. lighting conditions, distance to object and available mounting options will play a major role in selecting the appropriate camera. Panoramic cameras come in a variety of models with various strengths and weaknesses.
Panoramic Single Lens
The panoramic single lens or “fish eye” cameras can be an economical choice to achieve 360° of coverage and are frequently deployed in office lobbies convenience stores and directly above cash registers. These cameras can also be mounted on a wall resulting in a 180° field of view. One panoramic single lens camera can now be installed in lieu of multiple standard IP cameras resulting in an improved, unobstructed field of view. As a result, cost savings can be realized through the reduction of camera infrastructure requirements including cable, switches and power, reduced technician time for camera set up and programming, and a reduction of camera licensing requirements.
One potential area of concern when installing single lens panoramic cameras in lieu of multiple IP cameras would be the potential reduction of system resilience by creating a single point of failure. In more critical applications, this can be addressed by augmenting panoramic single lens cameras with a few strategic standard IP cameras to cover sensitive areas. This combination of panoramic and standard IP cameras may provide a better solution where a both a high level of situational awareness and a high level of reliability is required.
Panoramic single lens cameras also produce a spherical “fish eye” image. This image must be corrected to provide a usable image for viewing. The process of correcting the image is called “de-warping” and can be accomplished at the camera, or by using specialized software at the video management system headend to de-warp once the video has been transmitted. De-warping at the video management system allows the user to go back in time to view the entire scene in its original form and the ability to pan tilt and zoom within the entire 360° view. Another advantage to de-warping at the video management system is that it will allow multiple users to view the same image concurrently. However, de-warping at the camera allows the end user to create virtual views similar to those provided by standard IP cameras. The views may be changed by using pan tilt and zoom commands which can introduce latency issues similar to what is experienced with mechanical pan tilt and zoom functions. Finally, de-warping at the camera does not allow the ability to go back in time and view the entire scene in its original form.
Multi-Sensor Panoramic Dome
Multi-sensor panoramic cameras feature multiple fixed megapixel sensors with standard lenses installed within a single dome enclosure. This multi-sensor camera configuration provides an undistorted image so de-warping is not required. However, because we are dealing with multiple sensors viewing a single scene, special circuitry is still required to combine or “stitch” the information into a single usable view. Like the panoramic single lens camera, there is only one camera to install and one cable to pull. However, the power requirements increase for this type of camera and the overall size of the camera unit tends to be larger than a single lens camera. One potential difference with multi-sensor cameras is that their bandwidth requirements may necessitate a gigabit Ethernet connection. Depending on the manufacturer and model selected, these cameras can range anywhere from 5MP to 40MP, so it is important to utilize the appropriate cable and switches to support the bandwidth. Also, with the higher megapixel cameras, you may experience a cap on the allowable frames per second (fps). It is important to keep this in mind when considering the level of detail or forensics required for the application. Licensing must also be reviewed to determine if a single license or individual licenses for each sensor will be required.
Lastly, the mounting configuration and feature sets for these cameras will vary by manufacturer and model. Whether you are requiring a fully weather resistant unit complete with heater and blower, a vandal resistant IK-10 Impact unit, a wide dynamic range or day / night solution, you should be able to find a multi-sensor panoramic dome to fit the application.
Directional Multi-Sensor Dome
The third type of panoramic camera is a multi-sensor megapixel camera with directional sensors. While providing the same 180° and 360° field of view as the panoramic multi-sensor camera, directional multi-sensor cameras allow for each sensor to be individually adjusted and positioned to capture the desired field of view. This is achieved by using the four individual three-axis gimbals in the camera, which allow for the independent movement of each sensor.
You can easily configure a directional multi-sensor dome camera to provide a 270-degree field of view. This configuration is commonly utilized for exterior building corner mount applications, or other applications requiring unique angles of coverage like parking garages where you may be trying to simultaneously observe the parking areas and vehicle entrance and exit lanes. Some manufacturers provide the option to mix and match different lens options to include vari-focal lenses with remote zoom and focus capabilities which provides even greater flexibility. Due to the adjustability options for the sensors, these cameras are usually much larger than both the panoramic single lens cameras and the multi-sensor panoramic domes. It is also important to note that directional multi-sensor dome cameras are typically more expensive when compared to other panoramic cameras.
Conclusion
Panoramic cameras are not the single answer for all applications, but when used correctly they can help round out a robust video solution. The process of selecting the right camera technology must start with a thorough understanding of the overall design objectives. If the design objectives include a requirement for a high level of situational awareness over a relatively large field of view, panoramic cameras should be a top consideration. Due to the wide variety of camera choices and recording platforms, you will want to ensure you have done your due diligence during the design phase to make certain you have a cohesive and compatible system that meets all of the necessary requirements.
About the Authors:
Brian Dusza, PE, CPP is a Senior Director, Consulting Services for Securadyne Systems LLC, Marshall Amarantes is Director of Solutions Engineering for Securadyne Systems LLC,
