WLTOG: An optimization approach for wild large-range target omnidirectional geolocation based on monocular PTZ camera

As an omnidirectional monocular camera, the
pan-tilt-zoom (PTZ) camera has been widely employed in urban governance, forest
fire protection, traffic supervision due to its omnidirectional coverage and
inexpensive cost. Traditional monocular camera geolocation research focuses on
small-range geolocation with a central projection camera under ideal
conditions, making it difficult to meet the requirements of omnidirectional
coverage and large-range geolocation for PTZ cameras. In view of this, this
paper proposed a wild large-range target omnidirectional geolocation (WLTOG)
algorithm. Firstly, the WLTOG algorithm transforms the target in a single image
to the camera's visual center, obtaining the camera posture value. Then, it
fits the nonlinear mapping relationship between multiple pairs of PTZ camera
postures and the geospatial coordinates by using high-dimensional
overdetermined equation, and finally realizes the bidirectional calculation
between pixel coordinates and geospatial coordinates. The experimental PTZ
camera is mounted on a communication tower in wild hilly environment. This
method can be used to construct an omnidirectional geolocation relationship
that meets the requirements of omnidirectional geolocation within 945m based on
unknown accurate internal and external orientation elements, and low
requirements for wild hardware installation. The WLTOG algorithm is conducive
to the geometric measurement of a single image, GIS-augmented video
surveillance, and 3D object recognition.