Turbidity-based Aerial Perspective Rendering for Mixed Reality
Carlos Morales, Zhao Hongxun, Rei Kawakami, Oishi Takeshi, Katsushi Ikeuchi · International Symposium on Mixed and Augmented Reality · 2014
Rendering realistic scenes is one of the most significant objectives in outdoor Mixed Reality (MR) applications that are created by merging virtual objects into real scenes. One type of these applications consists on rendering a virtual object in a position that is distant from the observer. The goal in such applications is to realistically model the natural atmospheric effect of the real scene over the virtual object’s appearance. This natural phenomenon over distant objects in open air scenes is called aerial perspective and makes the object’s color turn fainter and shift towards the environmental light color. Nevertheless, aerial perspective modeling is challenging because outdoor illumination is unpredictable and changes arbitrarily. In computer vision (CV) and computer graphics (CG), the light scattering phenomena that cause the aerial perspective effect are generally modeled by a combination of a directly transmitted light and an airlight. While Preetham et al. (1999) performed a study using such model and rendered a turbidity-based aerial perspective for complete-virtual applications, only Zhao (2012) has carried out a research applied to MR. Zhao used a simple adjustment of Preetham’s aerial perspective model, however, only analyzed one atmospheric case and obtained a compute-intensive rendering. In this work, we propose an enhanced MR-directed scattering model using a full-spectrum turbiditybased approach and formulate an improved aerial perspective rendering model. For this purpose, we first estimate turbidity by matching the luminance distributions of a captured omnidirectional image and sky models. Then we employ the estimated turbidity to render a virtual object with aerial perspective effect.