Silhouette Parallax Occlusion Mapping in Modern Video Games: From Height-Field Ray Marching to Carved Real-Time Relief

Abstract

Parallax occlusion mapping (POM) is the standard way modern games add centimetre-scale relief to surfaces without the memory and vertex cost of tessellated geometry. Yet classical POM only shifts texture coordinates inside a mesh whose outline, depth and shadows remain flat, and the illusion breaks exactly where the eye looks: at edges, contacts and grazing angles. This paper presents the silhouette POM pipeline developed for Carve, a parallax occlusion mapping system for Unity's High Definition and Universal Render Pipelines. It details a metric formulation that measures relief depth in meters independently of the UV layout, the reconstruction of carved silhouettes on planar and curved meshes through bounded and quadric ray models, and a conservative per-pixel depth offset that lets shadows, contacts and screen-space effects see the relief. GPU strategies including min/max height-pyramid band marching, footprint-aware step budgeting and secant refinement are examined alongside relief-aware shading: soft self-shadowing, relief occlusion, specular occlusion and cliff shading. Finally, engine integration workflows and validation against displaced ground-truth geometry are discussed.