1. A computing device for detecting representations of physical objects in an image of a physical scene comprising the physical objects, the computing device comprising one or more processing units and computer-readable media comprising computer-executable instructions that, when executed by the processing units, cause the computing device to perform steps comprising: generating image features from two-dimensional image data obtained from the physical scene; generating geometric features from three-dimensional data obtained from the physical scene; identifying correspondences between the generated image features and the generated geometric features; combining the generated geometric features and the generated image features, the combining being in accordance with the identified correspondences between the generated image features and the generated geometric features; and detecting the representations of the physical objects in the image by coincidentally considering both the generated image features and the generated geometric features.