Disclosed herein according to one embodiment is an object tracker for tracking an object. The object tracker includes a depth camera for acquiring a 3D depth map and a low-resolution 2D image of the object, and an image camera for acquiring a high-resolution 2D image of the object. A processor is in communication with the depth camera and the image camera. The processor is configured to: identify a region of interest within the 3D depth map; identify an approximate object silhouette within the low-resolution 2D image using information about the region of interest from the 3D depth map; identify the approximate object silhouette in the high-resolution 2D image using information about the approximate object silhouette from the low-resolution 2D image; generate a refined object silhouette within the high-resolution 2D image using a region segmentation process; and track the object using the refined object silhouette.