Unpopping: Solving the Image-Space Blend Problem for Smooth Discrete LOD Transitions

This paper presents a new, simple and practical algorithm to avoid artifacts when switching between discrete levels of detail (LOD) by smoothly blending LOD representations in image space. We analyze the alternatives of conventional alpha-blending and so-called late-switching (the switching of LODs “far enough” from the eyepoint), widely thought to solve the LOD switching discontinuity problem, and conclude that they either do not work in practice, or defeat the concept of LODs. In contrast we show that our algorithm produces visually pleasing blends for static and animated discrete LODs, for discrete LODs with different types of LOD representations (e.g. billboards and meshes) and even to some extent totally different objects with similar spatial extent, with a very small runtime overhead. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism

• Type: Journal
• Year: 2007
• Where: CGF
• Authors: Markus Giegl, Michael Wimmer
• Keywords: CGF 2007, Discrete Lods, LOD Representations, LODs