3D computer graphics Study Guide

📖 Core Concepts Three‑dimensional computer graphics – Digital images created from 3‑D geometric data that are ultimately displayed on a 2‑D screen (or VR headset). 3‑D model – A mathematical representation (vertices + polygons) of an object; not an image until rendered. Rendering – Converting a 3‑D model + scene (lights, camera) into a 2‑D image. Production workflow – Three phases: Modeling → Layout & Animation → Rendering. Material – Defines how a surface interacts with light; supplied with textures (color/albedo, bump/normal, displacement). Projection – Mathematical transform that maps 3‑D coordinates onto a 2‑D plane for display. 📌 Must Remember Vertices are points; polygons are flat surfaces formed by ≥3 vertices. Keyframe animation records poses; the system interpolates between them. Inverse kinematics (IK) solves for joint angles to reach a target point. Bump/normal maps fake surface detail; displacement maps actually modify geometry. Realistic rendering → simulates light transport; non‑photorealistic rendering → artistic style. Common file formats: .blend, .obj, .fbx, .dx9/.dx11. 2.5D / isometric graphics = 3‑D world shown from fixed angles, no perspective distortion. GPU accelerates geometry processing and rasterization. 🔄 Key Processes Modeling Scan real object or create procedurally → generate vertices → connect into polygons. Layout & Animation Place objects, lights, cameras → define spatial relationships. Add animation: Record keyframes → interpolate (linear, spline). Apply IK for articulated figures. Import motion‑capture data if available. Run physical simulation (gravity, collisions) when needed. Rendering Choose material → attach appropriate textures. Compute lighting (realistic vs artistic). Project 3‑D scene onto 2‑D viewport. Output image; optionally send to a render farm for speed. 🔍 Key Comparisons 3‑D vs 2‑D graphics – 3‑D uses geometry, lighting, and projection; 2‑D relies on flat sprites or vector paths. Bump map vs Normal map – Both fake detail; normal maps store surface normals directly → more accurate lighting. Displacement map vs Normal map – Displacement actually moves vertices; normal only alters shading. Realistic vs Non‑photorealistic rendering – Realistic = physics‑based light transport; NPR = stylized, often ignores physics. Keyframe vs Motion Capture – Keyframe is artist‑driven; mocap records real motion data. ⚠️ Common Misunderstandings “A 3‑D model is already a picture.” → It’s just data; rendering creates the picture. “Bump maps change geometry.” → They only affect shading; geometry stays flat. “All GPUs do the same work.” – Some are optimized for rasterization, others for ray tracing. “2.5D is the same as 3‑D.” – 2.5D limits camera angles and often uses pre‑rendered sprites. 🧠 Mental Models / Intuition “Pipe” analogy – Think of the workflow as a factory line: raw material (scan/procedural) → shaping (modeling) → positioning & motion (layout/animation) → finishing (rendering). Light‑surface interaction – Materials are “rules” the light follows: albedo = base color, bump/normal = tiny hills, displacement = real hills. 🚩 Exceptions & Edge Cases Displacement maps are costly; use only when true geometry change is needed (e.g., close‑up shots). IK solvers can produce unnatural poses if joint limits aren’t enforced. Isometric projection removes perspective; good for strategy games but not for realistic scenes. 📍 When to Use Which Model source – Scan for real objects; procedural for repetitive or algorithmic shapes. Texture type – Use albedo for base color, normal map for fine detail, displacement only when silhouette matters. Rendering style – Choose realistic for product visualisation or film; NPR for stylized games or art. File format – .obj for simple geometry exchange; .fbx for animation data; .blend for full Blender projects. 👀 Patterns to Recognize Vertex → Polygon → Mesh hierarchy appears in every modeling question. Keyframe → Interpolation → Motion pattern in animation problems. Material → Texture → Light interaction pattern in shading/rendering questions. Projection matrix → 2‑D screen coordinates pattern in any camera‑related problem. 🗂️ Exam Traps Distractor: “Bump maps alter geometry.” – Wrong; they only affect shading. Distractor: “All 3‑D graphics require a GPU.” – Some simple renders can be CPU‑only. Distractor: “Isometric graphics use perspective projection.” – Incorrect; they use orthographic projection. Distractor: “Keyframe animation records every frame.” – Only selected frames; the rest are interpolated. --- Study this guide, visualize the pipeline, and you’ll be ready to tackle any 3‑D graphics exam question!