Computer Graphics Flashcards

Flashcards based on the ECM3423 Computer Graphics exam paper.

Motion Capture

Capturing the motion of a model from a real life actor, usually by placing markers on the actor’s body to record motion in real time. Markers tracked via calibrated cameras, and joint position estimated using triangulation.

Rendering Pipeline

Includes stages like modelling, transformation, lighting, rasterisation, and pixel shading. It transforms 3D objects into a 2D image by projecting vertices, applying lighting/shading, and rasterising into pixels.

Alpha Channel

In texture maps, represents transparency, allowing textures to have varying levels of opacity, enabling the rendering of transparent objects while maintaining realistic interactions.

MIP Mapping

In OpenGL, improves texture rendering by creating prefiltered texture images at different resolutions. Advantages include better texture quality at varying distances and enhanced performance.

Global Illumination

Simulates how light interacts with surfaces and scatters throughout a scene, considering both specular and diffuse lighting. Examples include ray tracing, path tracing, and radiosity.

Gouraud Shading

Characterized by L[D|S]E, representing a single diffuse or specular reflection.

Phong Shading

Characterized by L[D|S]E, representing a single diffuse or specular reflection.

Ray Tracing

Characterized by LDS*E, representing a single diffuse but multiple specular reflections.

Radiosity Method

Characterized by LD*E, representing multiple diffuse reflections.

Normals in Lighting Calculations

Determine how light interacts with a surface, affecting its brightness and shading. Different lighting models use normals to compute diffuse and specular reflections accurately.

Normals in Bump and Displacement Mapping

Simulate fine surface details without altering the geometry by perturbing normals, creating the illusion of bumps and deformations.

Normals in Surface Smoothing

Play a role in creating smooth surfaces. In techniques like Gouraud and Phong shading, normals are interpolated across vertices to create the illusion of smooth shading.

Phong Model for Caustics

Only considers local geometry and incoming light direction. It would not be affected by the gemstone. Colors of the velvet surface would be represented without any shadows or caustics.

Ray Tracing for Caustics

Approximates the velvet surface as diffuse, shadow rays are created, and the area is rendered in complete shadow without caustics.

Path Tracing for Caustics

Simulates complex interactions between light and objects, rendering realistic illumination on the cushion surface including caustics.

Z-buffer Algorithm

Handles occlusions by recording the depth of each rendered pixel and overwriting it if a new, closer surface is rendered on the same location.

Painters Algorithm

It is a better choice when alpha < 1. Can render the yellow bar by blending the pixel’s colour with the previous colour using the appropriate alpha instead of overwriting it