Gaming Graphical Effects ExplainedWritten by: Tero
Published on: Aug-04 20:37
The latest GD technical article is about the various graphics techniques used within gaming and graphics engines.
These techniques range from Anti-aliasing, mipmapping, Dynamic Range, Bloom, Lens Flare, Anisotropic Filtering and others. Well worth a read...
Anti-aliasing (AA) is a technique used to remove the jagged edges from the screen. This is achieved by taking samples from the objects on the screen and calculating the desired outcome. The multiplier of AA tells how many samples are taken, for example AA 4x takes 4 samples from the surrounding pixels. The more samples are taken, the better the outcome.
Full-scene anti-aliasing (FSAA), also known as super sampling anti-aliasing (SSAA), is a similar technique to AA but instead of taking samples from single objects, the samples are taken from the whole screen. This results in much better graphical quality but demands a lot of computational power.
Multisample anti-aliasing (MSAA) is very similar to FSAA but the samples are taken only from the points that are in need of anti-aliasing. This results in a slightly lower graphical quality but it also requires less computing from the GPU.
Mipmapping is a technique that uses a collection of pre-calculated images of the main texture to increase the rendering speed of that texture. The more images are used, the better the quality of the final texture and it also helps in reducing the aliasing artifacts.
High Dynamic Range
High dynamic range (HDR) is a way to render a scene by using lighting calculations in a large dynamic range. This allows the details to be seen in very bright or dark areas without using a high contrast ratio.
Bloom is a 'watered-down' version of HDR that uses the lighting of a scene to create a sort of an anti-aliasing effect on objects that are in front of a light source. This is done by simply drawing the light slightly on top of the objects edges.
Lens flare is a graphical effect which aims at creating a realistic scene of diffracting lights in the human lens. This results in "rays" of light that are emitted from a light source.
Tone mapping is a technique that's used in HDR to map the colors otherwise unavailable due to the limits of a computer monitor. This is especially noticeable when a scene is using 'over-bright' colors that the monitor could not normally draw.
Ambient occlusion (AO) is a shading method that uses the the geometry of an object to create a realistic lighting and shadows. This is done by taking into account the attenuation of light due to occlusion.
Screen Space Ambient Occlusion
Screen Space Ambient Occlusion (SSAO) is a type of ambient occlusion developed by Crytek. In SSAO, the rendering is done in real-time and much more effectively then in basic AO since SSAO analyzes the depth buffer which is stored in every texture. Horizon-Based Ambient Occlusion (HBAO) is an extension of SSAO which uses blur to enhance the lighting effects on an object.
Bilinear Filtering is a texture filtering method that uses bilinear interpolation on certain points on a texel to draw the textures more smoothly when they are displayed larger or smaller then they really are. Trilinear Filtering is an extension to this, using linear interpolation instead of bilinear.
Anisotropic Filtering (AF) is another method to filter textures. AF is very similar to Bilinear and Trilinear Filtering but it uses the camera position to determine how to smooth and sharpen the textures. This allows the distant textures to look less blurry and it also eliminates the aliasing effects. The amount of AF determines how far the textures are sharpened. For example using AF 8x doubles the sharpness of textures when compared with AF 4x.