Camera-based systems in dairy cattle were intensively studied over the last years. Different from this study, single camera systems with a limited range of applications were presented, mostly using 2D cameras. This study presents current steps in the development of a camera system comprising multiple 3D cameras (six Microsoft Kinect cameras) for monitoring purposes in dairy cows. An early prototype was constructed, and alpha versions of software for recording, synchronizing, sorting and segmenting images and transforming the 3D data in a joint coordinate system have already been implemented. This study introduced the application of two-dimensional wavelet transforms as method for object recognition and surface analyses. The method was explained in detail, and four differently shaped wavelets were tested with respect to their reconstruction error concerning Kinect recorded depth maps from different camera positions. The images' high frequency parts reconstructed from wavelet decompositions using the haar and the biorthogonal 1.5 wavelet were statistically analyzed with regard to the effects of image fore-or background and of cows' or persons' surface. Furthermore, binary classifiers based on the local high frequencies have been implemented to decide whether a pixel belongs to the image foreground and if it was located on a cow or a person. Classifiers distinguishing between image regions showed high (⩾0.8) values of Area Under reciever operation characteristic Curve (AUC). The classifications due to species showed maximal AUC values of 0.69.Keywords: dairy cattle, monitoring system, 3D camera, object recognition, wavelet transform
ImplicationThe prototype of a multi-Kinect system is presented that captures 3D data of dairy cows in motion for health monitoring. When fully developed, it will provide an inexpensive means of automated early lameness detection and livestock monitoring, thereby helping to increase animal welfare. The large amount of recorded data will provide a solid basis for scientific analyses and can help to deepen the understanding of connections between traits and genetics. Object recognition and methods to analyze the animals' surfaces from the 3D data are important developmental steps that are approached using the wavelet transform.
IntroductionSeveral camera-based studies were conducted over the last years yielding high rates of correct classification in lameness detection in dairy cows. Song et al. (2008), Pluk et al. (2012) and Viazzi et al. (2013) used digital 2D cameras to record walking cows from the side at distances of 3 to 6 m and analyzed step overlap, fetlock joints' angles or back posture. There were also several camera-based studies dealing with body condition score (BCS) determination. Azzaro et al. (2011) used linear and polynomial kernel principal analysis to reconstruct cows' shapes. Bercovich et al. (2012) presented BCS-prediction models that were based on five anatomical points. In both studies the animals were observed from a top view position using 2D cameras. The definitio...