During this year’s SIGGRAPH 2013, Jonathan Dupuy, Eric Heitz, Jean-Claude Iehl, Poulin Pierre, Fabrice Neyret and Victor Ostromoukhov presented a new graphical technique that could be used in next-gen (or next-next-gen) games. This new technique called ‘Linear Efficient Antialiased Displacement and Reflectance‘ (LEADR) is a reflectance filtering technique for displacement mapped surfaces that preserves surface appearance at all scales, is compatible with tessellation and promises to be the fastest, seamless, and antialiased progressive representation for displaced surfaces.
But what is the problem with ‘normal’ modern techniques such as normal mapping you ask? Well, let’s hear what the team had to say about it:
“Rendering applications such as video games commonly employ bump or normal textures (henceforth interchangeably referred to as normal textures) to enhance surface appearance. These textures perturb or modify the normal of a simple underlying surface to emulate geometric variations through shading perturbations. Similarly to albedo textures, normal textures must be filtered for antialiasing purposes. But since shading with linearly filtered normals does not result in proper reflectance filtering, these textures cannot exclusively rely on simple methods such as mipmapping.”
And here is where the biggest problem is according to the team who presented LEADP:
“Filtering appearance of small-scale geometry is thus a critical emerging problem. Indeed, small-scale geometry produces viewand light-dependent effects that include masking, shadowing, and projection weighting (i.e., the cosine term). Filtering this smallscale geometry while neglecting these visual effects violates energy conservation and can result in objectionable aliasing, popping artifacts, and inconsistent appearances throughout scales. Methods for filtering normal maps do not account for these effects, which is why filtering reflectance from normal mapping is not the same problem as filtering reflectance of small-scale geometry.”
In short, LEADP promises to eliminate any visual artifacts that can be caused by displacement mapping.
The team has also released two videos, showcasing this technique, that can be viewed below.
Linear Efficient Antialiased Displacement and Reflectance Mapping Part 1
Linear Efficient Antialiased Displacement and Reflectance Mapping Part 2