  Depth of Field (DoF) in games is usually achieved as a post-process effect by blurring pixels in the sharp rasterized image based on the defined focus plane. This paper describes a novel real-time DoF technique that uses ray tracing with image filtering to achieve more accurate partial occlusion semi-transparencies on edges of blurry foreground geometry. This hybrid rendering technique leverages ray tracing hardware acceleration as well as spatio-temporal reconstruction techniques to achieve interactive frame rates. 
Hybrid DoF: Ray-Traced and Post-Processed Hybrid Depth of Field Effect   for Real-Time Rendering