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Overview of Computer Graphics & Applications 2023

Instructor: 李同益

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CG System

Overview

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Triangle, quad,

curve surface

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Mesh

Simplification

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Level of Details (LOD)

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The teapot

Real teapot

Martin NewellMartin Newell, The teapot model was created in 1975 by early computer graphics researcher Martin NewellMartin Newell, The teapot model was created in 1975 by early computer graphics researcher Martin Newell, a member of the pioneering graphics program at the University of Utah.

https://www.youtube.com/watch?v=TIxt9guMbXo

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Utah Teapot’s Data

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Rendering

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Rendering/Shading

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Photo-realistic Rendering

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Rendering and Texture Mapping

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Direct v.s. Indirect Lighting

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2023/02/16

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Animation

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Gallery of AI

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A Standard Graphics Pipeline

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OpenGL Transformation �Pipeline

v

e

r

t

e

x

Modelview

Matrix

Projection

Matrix

Perspective

Division

Viewport

Transform

Modelview

Modelview

Projection

●

●

●

object

eye

clip

normalized

device

window

glTranslate{fd}( x, y, z )

glRotate{fd}( angle, x, y, z )

glScale{fd}( x, y, z )

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OpenGL Rendering

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Basic Idea of Ray tracing

Note: translucent materials allow some light to pass through. Transparent and translucent objects still form shadows, but they may be faint, fuzzy or colored.

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“Backward” Ray-Tracing

  • Trace rays from eye instead
  • Do work where it matters

Eye

Light

This is what most people mean by “ray tracing”.

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Raytracng

http://www.realtimerendering.com/raytracing.html

https://youtu.be/U9euLxgkR8c

The Ray Tracer Challenge

A Test-Driven Guide to Your First 3D Renderer

by Jamis Buck

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Shadow Rays

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Scanning the David

height of gantry: 7.5 meters

weight of gantry: 800 kilograms

大衛像 (David of Michelangelo))

大衛像是文藝復興時代米開朗基羅的傑作，於1501年至1504年雕成。雕像為白色大理石雕成的站立的男性裸體，一個佛羅倫薩藝術中最受歡迎的主題。用以表現聖經中的猶太英雄大衛王。原作目前置放於義大利佛羅倫斯美術學院，

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Michelangelo’s Pieta

handmade replica

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Molder Package

3ds Max 是由 Autodesk 公司開發的專業級 3D 動畫軟體，應用的領域包括電影視覺效果、遊戲場景與角色製作、建築工程與室內設計、工業產品設計等，從 DOS 系統的 3D Studio 到今年推出的 3ds Max 2017 版本已擁有超過 25 年的歷史，隨著版本更新不斷增加新的功能。

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Sketch �略圖，�草圖；

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Depth Cueing

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Clipping (Far-plane)

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Coloring

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Hidden Surface Removal

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Constant Rendering

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Facet Shading

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Smooth Shading

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Correct Highlight

(高亮度)

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Edge Silhouettes

輪廓

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Texture & Shadow

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Texture Mapping

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Surface Flattening �and �Texture Mapping

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Texture Mapping with Hard Constraints Using Warping

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In this image, the head on the left is a low-res model, the head in the middle is a highly detailed high-res model. The head on the right is the low-res model with a normal map generated from the hi-res model. It is visually almost indistinguishable from the high-poly model

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Shading with Scan Conversion�for Pixels

Lecture 15

6.837 Fall 2001

Bump/Normal Mapping and

Displacement Mapping

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Lecture 15

Slide 46

6.837 Fall 2001

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Procedural Texture

程序紋理

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Reflection

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Global Illumination

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Lighting

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Photo image of

the real scene

Non-photorealistic

Rendering

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Hatching

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Smooth Shading

NPR Cartoon Shading

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Computer Graphics is about Movies!

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Visual and Special Effects Film Milestones�

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Motion capture (mocap)

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Inspirational Video

Keep in mind: this film is entirely Computer-generated.

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Games are OK here

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Medical Visualization

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Computer Aided Design

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Scientific Visualization

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Word Cloud Visualization

http://graphics.csie.ncku.edu.tw/TVCG_Word_Cloud/Main_video.mp4

A tag cloud (word cloud, or weighted list in visual design) is a visual representation of text data, typically used to depict keyword metadata (tags) on websites, or to visualize free form text. Tags are usually single words, and the importance of each tag is shown with font size or color.[2] This format is useful for quickly perceiving the most prominent terms and for locating a term alphabetically to determine its relative prominence. When used as website navigation aids, the terms are hyperlinked to items associated with the tag.

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Graphical User Interfaces (GUIs)

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WYSIWYG NPR:�Drawing Strokes Directly on 3D Models�

http://www.cs.princeton.edu/gfx/proj/wnpr/

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Virtual

Reality

(VR)

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Head-Mounted Displays

https://www.youtube.com/watch?v=9HuVExgGFZ8

​

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Medical Applications

in Virtual Reality 

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Caves

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Looking at NASA Space Station on display wall

http://www.cs.princeton.edu/~benshedd/

CSDisplayWall8&24/index.html

                                                                         

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Display Wall

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Image/Video Retargeting

  • Adapt image/video content to different display devices
    • Resolution
    • Aspect ratio

​

​

​

16 : 9

? : ?

2.39 : 1

4 : 3

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Image Resizing

  • Need to fit images to various display media (wide-screen TV, PDA, thumbnail...)

4:3

16:9

1:1

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Resizing – Standard Solutions

  • Linear scaling
    • everything is distorted
  • Letterboxing
    • screen not fully utilized
  • Cropping
    • objects close to boundary are removed

© Blender Foundation

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Resizing – Standard Solutions

  • Linear scaling
    • everything is distorted
  • Letterboxing
    • screen not fully utilized
  • Cropping
    • objects close to boundary are removed

© Blender Foundation

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Resizing – Standard Solutions

  • Linear scaling
    • everything is distorted
  • Letterboxing
    • screen not fully utilized
  • Cropping
    • objects close to boundary are removed

© Blender Foundation

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Resizing – Standard Solutions

  • Linear scaling
    • everything is distorted
  • Letterboxing
    • screen not fully utilized
  • Cropping
    • objects close to boundary are removed

© Blender Foundation

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Resizing – Content-Aware Solutions

Seam-carving

[Avidan+Shamir 2007]

Non-homo. warping

[Wolf et al. 2007]

Optimized scale&stretch

[Wang et al. 2008]

Determine ‘important’ regions

Apply operator

[Visual Media Retargeting, SIGGRAPH Asia 09 Course]

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Seam carving: nonlinear cropping�[Avidan and Shamir 2007; Rubinstein et al. 2008]

  • Define an importance map (for example: gradients)

​

​

​

​

​

  • Remove lowest-energy 1D seams (one by one)

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Results

original

SC (Seam carving)

ours

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Video Resizing Results in SIGGRAPH Asia 2009

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Flickering and waving artifacts