Three-dimensional optimum nonlinear filter for detecting distorted target location and distance

摘要

Laser radar (LADAR) is a device to acquire the profile of an object. A 3D LADAR range image is encoded as a 2D image whose gray values represent the measured range. It is possible to apply 2D filters for recognition of 2D encoded range image to detect the location of a target. However, if we want to detect the target coordinate within the input scene, that is not only the location of a target but also the distance from a sensor, 3D data processing is needed. First, it is needed to convert 2D range image back into 3D space, and then apply a 3D filtering technique to detect the target location and the distance from the sensor. We set up and solve the minimization problem that leads to the derivation of the 3D distortion tolerant nonlinear filter by minimizing the output energy due to the additive noise and the energy of correlation output in response to the input scene with the false objects. This filter also has a capability to reject a certain target if we know exactly what to reject. The correlation output at the distance level of the target shows a dominant peak at the target location, and the correlation outputs at the distance of the adjacent target level shows a very small peak at the target location. We can detect the location and the distance at the same time of the distorted target using proposed 3D optimum filtering.