Summary of Introduction to 3D Computer Graphics

## Introduction 3D computer graphics is the practice of creating, manipulating, and rendering objects that have width, height, and depth in a digital environment. It enables designers, artists, engineers, and developers to build realistic or stylized worlds for games, products, architecture, simulation, and virtual reality. > **Definition:** A 3D scene is a digital representation of objects defined by points in space, connected geometry, surface properties, and simulated lighting. ## Core Concepts — broken down ### 1. Space and Primitives - **Vertex:** A single point in 3D space defined by coordinates $(x, y, z)$. - **Edge:** A line connecting two vertices. - **Face (Polygon):** A flat surface enclosed by edges, commonly triangles or quads. - **Mesh:** A collection of vertices, edges, and faces forming an object. > **Definition:** A vertex is a point with coordinates $x$, $y$, $z$ that locates geometry in 3D space. Practical example: A cube is modeled by 8 vertices, 12 edges, and 6 faces. ### 2. Modeling Techniques - **Polygonal modeling:** Build shapes from polygons (triangles/quads). Good for real-time use. - **NURBS & curves:** Use mathematical curves for smooth, precise surfaces (common in CAD). - **Sculpting:** Push/pull surface detail like digital clay for organic models. Did you know that polygonal meshes are typically converted to triangles for real-time rendering because GPUs process triangles most efficiently? ### 3. UV Mapping and Texturing - **UV mapping:** Unwrap a 3D surface onto 2D coordinates so textures can be painted or applied. - **Texture maps:** Color (albedo), normal maps (surface detail), roughness, metallic, ambient occlusion. > **Definition:** UV mapping is the process of assigning 2D texture coordinates to the surface of a 3D model. Practical example: For a character, use an albedo map for skin color and a normal map to fake small wrinkles. ### 4. Shaders and Materials - **Material:** A set of properties that describe how a surface looks (color, reflectivity, transparency). - **Shader:** A program that computes the final color of each pixel given lights, material properties, and view direction. Table: Comparison of common material workflows | Workflow | Real-time suitability | Strengths | Typical use | | --- | ---: | --- | --- | | PBR (Physically Based Rendering) | +++ | Consistent under varied lighting, realistic | Games, product viz | | Non-PBR / Stylized | ++ | Artistic control, less realistic | Cartoons, stylized games | | NURBS materials | + | Smooth surface shading | Industrial design | ### 5. Lighting and Rendering - **Lighting types:** Point, directional, spot, area lights. - **Rendering:** Convert the 3D scene into a 2D image; can be real-time (game engines) or offline (ray tracing). > **Definition:** Rendering is the process of generating the final image or animation from a 3D scene and its lighting. Practical example: Use area lights and a PBR material to create a realistic product render for a phone. ### 6. Rigging and Animation (overview) - **Rigging:** Create a skeleton or control system that lets you deform a model for animation. - **Animation:** Keyframe or procedural techniques move objects over time. > **Definition:** Rigging prepares a model with bones and controls so it can be animated. Note: This section introduces rigging and animation at a high level; detailed animation history is covered elsewhere. ### 7. Optimization and Real-time Constraints - **Level of Detail (LOD):** Use simpler meshes at a distance. - **Normal maps:** Preserve appearance while reducing polygon count. - **Bake lighting:** Precompute lighting into textures for faster runtime performance. Did you know that using a normal map can make a low-poly model look as detailed as a high-poly sculpt while keeping far fewer vertices? ## Software and File Formats - Common software: **Blender**, **Autodesk Maya**, **Cinema 4D**, **ZBrush**, **Unreal Engine**. - Common file fo