We present two linear algorithms for recovering the camera motion and 3D scene structure directly from the image data in a multi--image sequence. The first algorithm generalizes the point--based approach of Oliensis to intensities. The second generalizes the Lucas--Kanade optical-- flow method to a direct method. 1 Introduction Structure from motion (SFM), the problem of reconstructing an unknown 3D scene from multiple images of it, is one of the most studied problems in computer vision. Most SFM algorithms reconstruct the scene from previously computed feature correspondences, usually tracked points. Other algorithms are direct methods that reconstruct from the images intensities without a separate stage of correspondence computation. In this paper, we present a direct method that is non--iterative, linear, and capable of reconstructing from arbitrarily many images. Previous direct methods either were limited to a small number of images (two or three ), required strong assumption..