Three-dimensional models of natural environments and the mapping of navigational information.

Much evidence has accumulated in recent years, demonstrating that the degree to which navigating insects rely on path integration or landmark guidance when displaced depends on the navigational information content of their specific habitat. There is thus a need to quantify this information content. Here we present one way of achieving this by constructing 3D models of natural environments using a laser scanner and purely camera-based methods that allow us to render panoramic views at any location. We provide (1) ground-truthing of such reconstructed views against panoramic images recorded at the same locations; (2) evidence of their potential to map the navigational information content of natural habitats; (3) methods to register these models with GPS or with stereo camera recordings and (4) examples of their use in reconstructing the visual information available to walking and flying insects. We discuss the current limitations of 3D modelling, including the lack of spectral and polarisation information, but also the opportunities such models offer to map the navigational information content of natural habitats and to test visual navigation algorithms under 'real-life' conditions.