Sun Dogs and Fish-Eye Paintings

Human binocular vision takes in about a half-space, at least along the horizontal. How to depict that? It is not possible with linear perspective. In photography one uses the ‘angle-true’ fish-eye lens, known as the ‘Postel projection’ in the arts and ‘Riemann normal coordinates’ in geometry. We show examples of artists (intuitively) using an even more extreme mapping, perhaps preferred because it strongly emphasises the centre of interest. ‘Sun dogs’ are an atmospherical optics phenomenon that allows a quantitative study. We identify a number of artworks that yield a fresh angle on the topic. They are (geometrically) very similar, but reveal an extreme boosting of central content. If the Postel is considered ‘veridical’ (its contender, linear perspective, is out) then the artistically preferred rendering is highly nonveridical. Yet one can hardly complain that the paintings fail to suggest a powerful and visually effective presentation of actuality. One needs some rethinking of representational optics here. It might be useful in other (also technical) contexts too.