Technologies Used In Graphics Rendering

Presented By:Bhupinder Singh

Basic Terminology• Pixel is the most basic unit of a digital image, a tiny square of color.• Resolution is the number of pixels in each dimension that can be

displayed. It is usually quoted as width × height, with the units in pixels.• Frame Rate is the rate at which an imaging device produces unique

consecutive images called frames. It is most often expressed in frames per second (FPS).• Refresh Rate is the number of times a display updates per second. It

is measured in Hertz (Hz).

• GPU – Graphics Processing Unit• Dedicated vs. Integrated• Nvidia vs AMD• Nvidia i. GeForce, the gaming graphics processing products for which Nvidia is best

known.ii. Quadro, computer-aided design and digital content creation workstation

graphics processing products.iii. Tegra, a system on a chip series for mobile devices.• AMD i. Radeon, brand for consumer line of graphics cards.ii. FirePro, brand for professional line of graphics cards for workstations.iii. Mobility Radeon, power-optimized versions of Radeon graphics chips for use in

laptops and mobile devices.

Rendering• It is the process of generating an image from a 2D or 3D model (or

models in what collectively could be called a scene file), by means of computer programs.• If a scene is to look relatively realistic and predictable under virtual

lighting, the rendering software should solve the rendering equation.• This is the key academic/theoretical concept in rendering. It serves as

the most abstract formal expression of the non-perceptual aspect of rendering.

Anti - Aliasing• If you draw a diagonal line with square pixels, their hard

edges create a jagged ‘staircase’ effect. This jaggedness is called aliasing.

• To counter this problem, anti – aliasing is used which works by rendering frames at a higher resolution than the display resolution, then squeezing them back down to size.

• Consider a pixel on a tile roof. It’s orange, and next to it is a pixel representing a cloudy sky, which is light and blueish. Next to each other, they create a hard, jagged transition from roof to sky. But if you render the scene at four times the current resolution, that one orange roof pixel becomes four pixels. Some of those pixels are sky - colored and some are roof - colored. If we take the average of all four values, we get something in between. Do that to the whole scene and the transitions become softer.

• While it looks very good, anti - aliasing is extremely computationally expensive. You’re rendering each frame at a resolution two or more times higher than the one you’re playing at—even with four GTX Titans, trying to run anti - aliasing with a display resolution of 2560x1440 isn't practical.• This was the Supersampling (SSAA) approach. Other comparatively less

taxing approaches are as follows.• Multisampling (MSAA): Achieves good results, but is much more efficient

than SSAA. This is typically the standard, baseline option in games.• Coverage Sampling (CSAA): Nvidia's more efficient version of MSAA.• Custom-filter (CFAA): AMD’s more efficient version of MSAA.• Fast Approximate (FXAA): Rather than analyzing the 3D models (i.e.

MSAA, which looks at pixels on the edges of polygons), FXAA is a post-processing filter, meaning it applies to the whole scene after it has been rendered, and it's very efficient. It also catches edges inside textures which MSAA misses.

Ambient Occlusion• It is a shading and rendering technique used to calculate how exposed each

point in a scene is to ambient lighting.• An ambient light source represents a fixed - intensity and fixed - color light

source that affects all objects in the scene equally. Upon rendering, all objects in the scene are brightened with the specified intensity and color. This type of light source is mainly used to provide the scene with a basic view of the different objects in it. This is the simplest type of lighting to implement and models how light can be scattered or reflected many times producing a uniform effect.• Ambient lighting can be combined with ambient occlusion to represent how

exposed each point of the scene is, affecting the amount of ambient light it can reflect.

• Ambient occlusion attempts to improve the effect by determining which parts of the scene shouldn't be exposed to as much ambient lighting as others. It doesn't cast hard shadows like a directional light source, rather, it darkens interiors and crevices, adding soft, diffused shading.• Screen space ambient occlusion (SSAO) is an approximation of

ambient occlusion used in real-time rendering, and has become commonplace in games in the past few years—it was first used in Crysis. It is effective in adding depth to a scene. All major engines support it, and its success will vary depending on the game and implementation.

High Dynamic Range Rendering• It 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.• The range it refers to is the range of luminosity in an image—that is, how dark and

bright it can be. The goal is for the darkest areas to be as detailed as the brightest areas. A low-dynamic-range image might show lots of detail in the light part of a room, but lose everything in the shadows.• Graphics processor company Nvidia summarizes the motivation for HDRR in three

points: bright things can be really bright, dark things can be really dark, and details can be seen in both.• In the past, the range of dark to light in games was limited to 8 bits (only 256 values),

but as of DirectX 10 128-bit HDRR is possible.

• Anisotropic Filtering: In 3D computer graphics, anisotropic filtering (abbreviated AF) is a method of enhancing the image quality of textures on surfaces of computer graphics that are at oblique viewing angles with respect to the camera. Anisotropic filtering does not filter the same in every direction. Anisotropic filtering generally comes in 2x, 4x, 8x, and 16x levels. Nvidia describes these sample rates as referring to the steepness of the angle the filtering will be applied to.• PhysX is a multi-threaded physics simulation SDK available

for Microsoft Windows, Mac OS X, Linux, PlayStation 3, Xbox 360 and Wii. It supports rigid body dynamics, soft body dynamics, vehicle dynamics, particles, volumetric fluid simulation and cloth simulation including tearing and pressurized cloth.

Motion Blur• Motion blur is pretty self-explanatory: it's a post-processing

filter which simulates the film effect caused when motion occurs while a frame is being captured, causing streaking.• In computer animation this effect must be simulated as a virtual

camera actually does capture a discrete moment in time. This simulated motion blur is typically applied when either the camera or objects in the scene move rapidly.

Depth Of Field• It is the distance between the nearest and farthest objects in a scene

that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.• In some cases, it may be desirable to have the entire image sharp, and

a large DOF is appropriate. In other cases, a small DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background.

Vertical Sync• To understand the importance of vertical sync, we first need to look at the

concept of screen tearing.• When a display's refresh cycle is out of sync with the game's rendering cycle, the

screen can refresh just as the game has finished supplying a frame and started on another one. The effect is a ‘break’ called screen tearing, where we're seeing portions of two or more frames at the same time.• In other words, it is a visual artifact in video display where a display device shows

information from two or more frames in a single screen draw• The artifact occurs when the video feed to the device isn't in sync with the

display's refresh. This can be due to non-matching refresh rates or simply from lack of sync between two equal frame rates. During video motion, screen tearing creates a torn look as edges of objects (such as a wall or a tree) fail to line up.

• Vertical synchronization is an option in most systems, wherein the video card is prevented from doing anything visible to the display memory until after the monitor finishes its current refresh cycle.• With Nvidia cards there is an option to enable 'Adaptive Vsync'. This

option will only turn on vertical synchronization when the frame rate of the rendering engine exceeds the display's refresh rate, leaving the frame rate unlocked otherwise. This eliminates the stutter that occurs as the rendering engine frame rate drops below the display's refresh rate.• In gaming terms, Vsync prevents the game from messing with the

display until it completes its refresh cycle. Unfortunately, Vsync causes its own problems, one being that it contributes to input lag when the game is running at a higher frame rate than the display's refresh rate.

Bloom• Bloom is a computer graphics effect used in video games and high

dynamic range rendering (HDR) to reproduce an imaging artifact of real-world cameras. The effect produces fringes (or feathers) of light extending from the borders of bright areas in an image, contributing to the illusion of an extremely bright light overwhelming the camera or eye capturing the scene.• It is a famously overused effect that attempts to simulate the way

bright light can appear to spill over edges, a visual cue that makes light sources seem brighter than they are. It can work, but too often it's applied with a thick brush, making distant oil lamps look like nuclear detonations.

Newer & Advanced Technologies

• Bump Mapping

• Particle System

• Crepuscular Rays [ God Rays ]

Bump Mapping

Particle System

Crepuscular Rays [ God Rays ]

Future Scope

•Parallel Processingi. Nvidia SLIii. AMD CrossfireX

•Oculus Rift

•4K Gaming

Oculus Rift

Conclusion • These are the major techniques used in rendering realistic and lifelike

images and find vast applications in the multi – billion dollar video gaming industry as well as computer – aided design and scientific purposes.• The highest end GPUs with dual or quadruple configurations may be

required to make use of these techniques at their highest levels. In mid – level consumer devices, tradeoffs are often made between these technologies to achieve a steady frame rate as well as a steady balance between efficiency and graphic realism.• Following are some screenshots of popular high end video games

deploying these techniques to their fullest.

References•www.pcgamer.com Popular blogging site for everything gaming related.

•gamescom Cologne, Germany Press Conferences

The world’s largest gaming event.

•www.Wikipedia.org