Mitigating relief inversion illusion with multidirectional sky illumination model: A user study

Le résumé fourni par la source

Relief presentation on maps has been developed in cartography for many centuries, yet it continues to receive attention in the digital era (e.g.Putto et al 2014).To represent elevation, relief is often illustrated as shading on shaded relief maps (SRM), typically using a single light source approximated by the Lambertian assumption (Kennelly & Stewart 2014).The recommended direction of the light source is from northwest (NW, azimuth 315°) (Imhof, 1965) or north-northwest (NNW, azimuth 337.5°) (Biland & Çöltekin 2017, Çöltekin & Biland 2019).When the light source is placed so that illumination comes from NW or NNW, the visualization should support comprehension of the SRM , specifically because it prevents a visual illusion which perceptually inverts the relief (Bernabé & Çöltekin 2014).As shown empirically by Biland & Çöltekin (2017), the strongest illusion appears for a light source with an azimuth of 225°.Relief inversion refers to users perceiving concave forms (e.g., a river valley on maps) as convex, and vice versa; concave shapes (such as mountain ridges on maps) are perceived by users as concave ones.This illusion, documented as early as 1786 by Rittenhouse (1786), is a result of the overhead illumination bias, meaning the human brain is used to processing images illuminated from above, which is the assumed direction of light, and if this is violated, previous implicit knowledge interferes with perceptual signal, and cognitive system can 'prefer' the previous knowledge, e.g., that the shadows are typically below the objects, and thus interpret the scene incorrectly.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.