This paper introduces single-image 3D scene reconstruction from water reflection photography, i.e., images capturing direct and water-reflected real-world scenes. Water reflection offers an additional viewpoint to the direct sight, collectively forming a stereo pair. The water-reflected scene, however, includes internally scattered and reflected environmental illumination in addition to the scene radiance, which precludes direct stereo matching. We derive a principled iterative method that disentangles this scene radiometry and geometry for reconstructing 3D scene structure as well as its high-dynamic range appearance. In the presence of waves, we simultaneously recover the wave geometry as surface normal perturbations of the water surface. Most important, we show that the water reflection enables calibration of the camera. In other words, we show that capturing a direct and water-reflected scene in a single exposure forms a self-calibrating catadioptric stereo camera. We demonstrate our method on a number of images taken in the wild. The results demonstrate a new means for leveraging this accidental catadioptric camera.
TORRALBA, Antonio; FREEMAN, William T. Accidental pinhole and pinspeck cameras: Revealing the scene outside the picture. In: 2012 IEEE Conference on Computer Vision and Pattern Recognition. IEEE, 2012. p. 374-381 @cite_28
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We identify and study two types of “accidental” images that can be formed in scenes. The first is an accidental pinhole camera image. These images are often mistaken for shadows, but can reveal structures outside a room, or the unseen shape of the light aperture into the room. The second class of accidental images are “inverse” pinhole camera images, formed by subtracting an image with a small occluder present from a reference image without the occluder. The reference image can be an earlier frame of a video sequence. Both types of accidental images happen in a variety of different situations (an indoor scene illuminated by natural light, a street with a person walking under the shadow of a building, etc.). Accidental cameras can reveal information about the scene outside the image, the lighting conditions, or the aperture by which light enters the scene.