[其它] Fast Global Illumination Baking via Ray-Bundles

[复制链接]

彬彬

797 主题	1 听众	1万积分

资深设计师

Rank: 7 Rank: 7 Rank: 7

纳金币: 5568
精华: 0

电梯直达

楼主

发表于 2012-1-5 08:36:19 |只看该作者 |倒序浏览

1 Introduction

In interactive applications such as video games, light maps are often

used to generate realistic images. However, baking light maps

is time consuming because it is necessary to compute global illumination.

This sketch presents a simple and fast rendering system

for light maps. Our system exploits ray-bundles on DirectX

R 11

capable GPUs and outperforms ray tracing based methods. Furthermore,

it supports tessellation for DirectX 11 games.

1.1 Related Work

Ray-bundles The use of global ray-bundles was introduced by

Sbert [1996]. Szirmay-Kalos and Purgathofer [1998] used global

ray-bundles for global illumination algorithm based on finite elements.

They compute radiance exchange between visible surfaces

using rasterization. Hachisuka [2005] proposed ray-bundles using

rasterization for final gathering. To obtain each depth fragment,

depth peeling [Everitt 2001] was used. Hermes et al. [2010] used

k-buffer [Callahan et al. 2005] and they demonstrated high-quality

global illumination with multiple glossy reflections using their radiance

exchange.

Per Pixel Linked-list Everitt [2001] introduced a multi-pass rendering

method called depth peeling for order independent transparency.

Ideally, we would need to store a list of fragments per

pixel as A-buffer [Carpenter 1984] in a single-pass. Callahan et

al. [2005] proposed k-buffer. Although it can be created in a

single-pass, the number of fragments per pixel is fixed. Yang et

al. [2010] introduced a method to dynamically construct highly

concurrent linked-list on DirectX 11 GPUs. This method is faster

than depth peeling for calculating order independent transparency,

and provides unlimited storage per pixel unlike k-buffer. For order

independent transparency, the fragments in the list need to be

sorted.

Tessellation DirectX 11 GPUs support hardware tessellation. It

enables real-time graphics to use arbitrary tessellation methods.

However, it is not easy for offline rendering. In order to obtain

exactly the same appearance both in real-time graphics and offline

rendering, offline renderers and real-time rendering engines have to

use the same tessellation method. The simplest solution is to first

tessellate the polygons. However, this is memory consuming. A

complex and costly out-of-core rendering system may be needed.

Direct ray tracing [Smits et al. 2000; Ogaki and Tokuyoshi 2011] is

one of the solutions, but arbitrary tessellation methods are still difficult.

Our renderer is able to support the same tessellation methods

for real-time graphics without a complex implementation.