A method for acquiring a pseudo-3D box from a 2D bounding box in a training image is provided. The method includes steps of: (a) a computing device acquiring the training image including an object bounded by the 2D bounding box; (b) the computing device performing (i) a process of classifying a pseudo-3D orientation of the object, by referring to information on probabilities corresponding to respective patterns of pseudo-3D orientation and (ii) a process of acquiring 2D coordinates of vertices of the pseudo-3D box by using regression analysis; and (c) the computing device adjusting parameters thereof by backpropagating loss information determined by referring to at least one of (i) differences between the acquired 2D coordinates of the vertices of the pseudo-3D box and 2D coordinates of ground truth corresponding to the pseudo-3D box, and (ii) differences between the classified pseudo-3D orientation and ground truth corresponding to the pseudo-3D orientation.