acquiring a raw image that includes geometric distortion of a lens of an image sensor that obtained the raw image, where the image sensor is a dual or more-pixel sensor having a plurality of pixels, with each pixel of the dual or more-pixel sensor comprising plural photodiodes;

acquiring a corrected image resulting from a performed geometric correction on the raw image;

based on the raw image, determining a vector toward a focal plane for each of multiple pixels, from among the plurality of pixels, based on an intensity difference acquired from two photodiodes selected from the plural photodiodes in each of the multiple pixels; and

estimating a pose based on the determined vectors.