A normal candidate information generation unit of an information processor generates normal candidate information for each pixel indicating, for example, a zenith angle, or an azimuth angle, or a zenith angle and an azimuth angle, on the basis of a polarization image in a plurality of polarization directions obtained by a polarization imaging unit. The in-plane pixel selection unit selects a plurality of pixels indicating the plane to be observed in the polarization image. A normal calculation unit calculates a normal of the plane to be observed on the basis of the normal candidate information of the pixels selected by the in-plane pixel selection unit.