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How electro-optical sensor modules with full HD resolution or higher, enhance the detection, recognition, and identification capabilities of situational awareness, long- range observation and designator systems.
To improve the information gathered from situational awareness, long-range observation and designator systems, the big trend is to gather full motion video 24/7 with the addition of more daylight video cameras to multi-sensor modules. In comparison to still images, full motion video allows for monitoring activity over time, observing behaviors, and also reduces the chance of missing critical details through continuous viewing. Increased resolutions further improve the capabilities of these systems.
The latest full HD image sensors have the sensitivity required to deliver low noise images in difficult light situations. Full motion HD video cameras (with frame speeds of 30+ fps) include optimized functionality to adjust for changing lighting conditions and other atmospheric conditions such as fog and other image processing needed for viewing such as accurate color reproduction and automatic white balance. With color processing, advanced edge enhancement significantly improves the sharpness of the image. There are true rugged options that can provide 24/7 operation on airborne and ground platforms. The cameras can be combined with zoom optics for even better identification performance.
One goal is to increase the probability for identification from the same distance by increasing the resolution to HD or higher. This is based on Johnson’s Criteria which describes the minimum number of pixels to give a 50 percent probability of an observer discriminating an object to the specified level. (Click here for more details on this.)
As the video modules become more prevalent there are a variety of users with different levels of training. So one of the biggest advantages of HD resolution and higher is the ability to increase the percentage of people who are able to identify an object rather than just detect it from the same distance.
Or another way to look at it would be that higher resolution increases the distance for an observer to be able to discriminate an object to a certain level. This increases the distance from potential danger or gives more time to react to threats.
While the resolution (the number of pixels on an image sensor) does not increase the detection, recognition, and identification (DRI) ranges, it does increase the field of view (FOV). For example, for standard definition vs. full HD, full HD provides 2.5 times the FOV. It is the optical resolution (MTF or lp/mm) that increases the DRI ranges. The lp/mm is directly dependent on the pixel size (lp/mm= 1000/(2*pixel size)). Of course these two are related to each other when creating an image sensor. Full HD sensors almost always have a smaller pixel size otherwise the sensor becomes very large. The disadvantage of smaller pixels is the sensitivity of the sensor. There is an optimum combination available on the latest CCD sensors used in rugged cameras.
The conclusion is that in order to increase DRI-ranges, you have to use capable optics but also the latest image sensor technology in the camera to benefit from your improved optics design. Just looking at the number of pixels is not enough. Performance of the camera over time and over the environmental operating range is essential in mission critical situations.
