Aliasing Flashcards
(18 cards)
Aliasing occurs when…
A digital sampling process cannot accurately represent a continuous signal
The Wagon-Wheel effect is where wheels appear to be stationary in videos. This is caused by […] and is a form of […] aliasing.
Caused by insufficient frame rates, and is a form of temporal aliasing
The Fourier analysis states that…
Any signal can be decomposed into a sum of sine waves of different frequencies, amplitudes and phases
The Nyquist limit states that to accurately capture a signal…
You must sample at a frequency at least twice the highest frequency present in the signal
Aliasing in computer graphics commonly manifests as… (pick one)
Jagged edges, flickering patterns, moire effects
Computer graphics face unique challenges with aliasing because…
Real-world scenes contain unlimited frequency content, hence some frequencies will always exceed the Nyquist limit
Filtering approaches face challenges in computer graphics because…
These approaches must be approximated during the rendering process
Area sampling is a pre-filtering antialiasing method, which involves…
Integrating the signal over each pixel area and assigning the average value to that pixel’s intensity
Weighted area sampling is a pre-filtering antialiasing method, which involves…
Integrating the signal over each pixel area, and assigning a weighted average value to that pixel’s intensity, giving a larger weight to points closer to the pixel center
Antialiased line drawing is a pre-filtering antialiasing method, which involves…
Determining pixel illumination based on the perpendicular distance from the pixel to the ideal line. Pixels on the line path receive full intensity, while those further away progressively receive partial illumination
Super-sampling anti-aliasing (SSAA) is a post-filtering antialiasing method applied after rasterisation, which involves…
Rendering the image at a higher resolution than the display, then down sampling it to the screen resolution
Multisample anti-aliasing (MSAA) is a post-filtering antialiasing method applied after rasterisation, which involves…
Processing fragment shaders only once per pixel, super-sampling only the depth and stencil buffers
Fast approximate anti-aliasing (FXAA) is a post-filtering antialiasing method applied after rasterisation, which involves…
Identifying the edges and selectively smoothing them at the pixel level
Textures can also experience aliasing, due to situations where…
Multiple texels map to one pixel, or one texel maps to multiple pixels
MIP mapping is a texture antialiasing method, which involves…
Precomputing multiple downsampled versions of a single texture, where textures of a lower resolution are selected when the texture is further away
Bilinear filtering aids in the MIP mapping process by…
Interpolating between neighbouring texels
Trilinear filtering aids in the MIP mapping process by…
Interpolating between MIP map levels for smoother transitions in real-time
Antrioscopic filtering aids in the MIP mapping process by…
Sampling textures at different horizontal and vertical ratios to prevent blurring
