# Appearance and Shape from Water Reflection

## TL;DR

This paper presents a novel method for reconstructing 3D scene structure and appearance from water reflection images, enabling self-calibration of HDR stereo cameras and handling wave-induced surface perturbations.

## Contribution

It introduces a principled iterative approach to disentangle scene radiometry and geometry from water reflection images, including calibration and wave surface recovery.

## Key findings

- Successful 3D reconstruction and appearance recovery from water reflection images.
- Demonstration of self-calibrating HDR stereo camera using water reflections.
- Effective handling of wave surface perturbations in reconstruction.

## Abstract

This paper introduces single-image geometric and appearance 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, for the first time, we show that capturing a direct and water-reflected scene in a single exposure forms a self-calibrating HDR 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.