This specification describes a method comprising generating, from a plurality of first images representing a scene, at least one stereoscopic panoramic image comprising a left-eye panoramic image and a right-eye panoramic image. Depth map images are generated corresponding to each of the left and right-eye panoramic images. Each of the left and right-eye panoramic images are re-projected to obtain a plurality of second images, each associated with a respective virtual camera. Each of the left and right-eye depth map images are re-projected to generate a re-projected depth map associated with each second image. A first three-dimensional model of the scene based on the plurality of second images is determined. A second three-dimensional model of the scene based on the plurality of re-projected depth map images is determined. One or more corresponding points of the first and second three-dimensional models is or are compared to determine a scaling factor.