1. A method comprising: capturing at least two images of a planar object; determining a first pose, comprising a position and an orientation, of a first mobile platform with respect to the planar object using the at least two images; warping an image of the planar object captured by the first mobile platform using the orientation of the first mobile platform with respect to the planar object to produce a reference image of a front view of the planar object; and determining a second pose of a second mobile platform with respect to the planar object using a second image of the planar object captured by the second mobile platform and the reference image; wherein determining the first pose, comprising the position and the orientation, of the first mobile platform with respect to the planar object comprises: extracting features from the at least two images; computing a 2D-2D homography h between the at least two images using the features; computing 3D coordinates for the features to define a 3D plane that corresponds to a plane of the planar object; computing a 3D-2D homography H between the 3D plane and one of the at least two images using the features and the 3D plane; and using the 3D-2D homography H to determine the first pose.