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High dynamic range rendering 58
High dynamic range rendering
In 3D computer graphics, high dynamic
range rendering (HDRR or HDR
rendering), also known as high dynamic
range lighting, is the rendering of computer
graphics scenes by using lighting
calculations done in a larger dynamic range.
This allows preservation of details that may
be lost due to limiting contrast ratios. Video
games and computer-generated movies and
special effects benefit from this as it creates
more realistic scenes than with the more
simplistic lighting models used.
Graphics processor company Nvidia
summarizes the motivation for HDRR in
A comparison of the standard fixed-aperture rendering (left) with the HDR
rendering (right) in the video game Half-Life 2: Lost Coast
three points: [1] 1) bright things can be really bright, 2) dark things can be really dark, and 3) details can be seen in
both.
History
The use of high dynamic range imaging (HDRI) in computer graphics was introduced by Greg Ward in 1985 with
his open-source Radiance rendering and lighting simulation software which created the first file format to retain a
high-dynamic-range image. HDRI languished for more than a decade, held back by limited computing power,
storage, and capture methods. Not until recently has the technology to put HDRI into practical use been developed. [2]
[3]
In 1990, Nakame, et al., presented a lighting model for driving simulators that highlighted the need for
high-dynamic-range processing in realistic simulations. [4]
In 1995, Greg Spencer presented Physically-based glare effects for digital images at SIGGRAPH, providing a
quantitative model for flare and blooming in the human eye. [5]
In 1997 Paul Debevec presented Recovering high dynamic range radiance maps from photographs [6] at SIGGRAPH
and the following year presented Rendering synthetic objects into real scenes. [7] These two papers laid the
framework for creating HDR light probes of a location and then using this probe to light a rendered scene.
HDRI and HDRL (high-dynamic-range image-based lighting) have, ever since, been used in many situations in 3D
scenes in which inserting a 3D object into a real environment requires the lightprobe data to provide realistic lighting
solutions.
In gaming applications, Riven: The Sequel to Myst in 1997 used an HDRI postprocessing shader directly based on
Spencer's paper [8] . After E³ 2003, Valve Software released a demo movie of their Source engine rendering a
cityscape in a high dynamic range. [9] The term was not commonly used again until E³ 2004, where it gained much
more attention when Valve Software announced Half-Life 2: Lost Coast and Epic Games showcased Unreal Engine
3, coupled with open-source engines such as OGRE 3D and open-source games like Nexuiz.