1. A method for three-dimensional (3D) sensing comprising: obtaining a two-dimensional (2D) image of an object taken from a viewing angle; extracting a 2D skeleton of the object from the 2D image, the 2D skeleton including a 2D skeleton line representing a section of the object, extracting the 2D skeleton including: calculating probabilities of pixels in the 2D image being part of the section of the object; locating the section of the object based on the calculated probabilities; calculating, for pixels on a same scanning line in the section, a skeleton point of the scanning line by performing a weighted averaging on positions of the pixels on the scanning line using the calculated probabilities of the pixels on the scanning line as weighting factors; and obtaining the 2D skeleton line by connecting skeleton points on different scanning lines; and calculating a 3D skeleton of the object based on the 2D skeleton, the 3D skeleton including a 3D skeleton line representing the object.