Sensibility Аnalysis of the Object Tracking Algorithms in Thermal Image

 

Nataša Vlahović

Stevica Graovac

 

In military application target tracking has always been an interesting and challenging problem. Nowadays, it has also found its place in civil applications, especially concerning surveillance and monitoring. Until recently, thermal imagery (image is formed based on infrared spectrum radiation) was considered only in military applications because of the price and size of cameras. Also, thermal image quality was not as good as TV (image is formed based on visual spectrum radiation) camera image. The situation has changed, and thermal cameras are now widely used in many kinds of applications. Thermal  image is different from TV camera image,  as it measures temperature difference between objects and background. Therefore,  it has an advantage over television cameras, since it can be used in low light conditions and in dark. This paper examines the options for a coarse and quick algorithm for rough target locating in thermal image, where the target is a small Unmanned Aerial Vehicle (UAV). Three different feature descriptor algorithms are tested in thermal imagery target tracking. Feature descriptor methods are widely used in visual imagery, but the goal of this paper is to examine their usage in thermal imagery. That is why three different feature descriptor algorithms from three different families are tested: FREAK (Fast Retina Keypoint), SURF (Speeded Up Robust Features) and MSER (Maximally Stable Extremal Regions). The algorithms are tested in case of translation, rotation, blur and size change of an object of interest, as well as in the case of noisy image. Since none of the tested methods works great in different situations, new, multi-stage algorithm is proposed. This algorithm is based on MSER and SURF algorithm combination, with a goal to use the advantages of each of them in different real situations. The obtained results show that the new, multi-stage algorithm has got the best performance among the group of the tested methods. All the algorithms are implemented in Matlab software.

 

Key words: target tracking, assessment, thermal image, algorithm, feature descriptors