An unsupervised method is presented for determining size of an object captured in an image. The method includes: capturing a set of images with a camera, where each image in the set of images is captured with the camera set at a different f-number; for each image in the set of images, computing a quality metric for the image, where the qualitymetric quantifies focus using contrast; identifying a given image in the set of images using the contrast metrics and the f-number of the camera; calculating a hyperfocal distance using parameters of the camera when taking the given image; and quantifying one or more dimensions of the object as a function of the hyperfocal distance; and if the object is known, using a view classifier to estimate the dimension in 3D.