Computer Graphics
文章目录
教程
曲线曲面:参数曲线、参数几何代数形式 https://blog.csdn.net/Jurbo/article/details/75046766
英语专业名词
CS184 教程
Lecture 0, Other notes
| Instructor | 导师,教育者 |
|---|---|
| instructional | 教学的,教育的 |
| registrar | (大学)教务长,教务主任;登记员 |
| Instructors and TAs | teacher assistants |
| roster | 执勤名单;候选名单 |
| class roster | 老师的点名册(花名册);名册 |
| teaching staff | 教职员;教师;教育工作者 |
| user-programmable vertex engine | |
| vertex | 顶点 |
| fragment shaders | 像素着色器 |
| as of | 在……是 |
| as of last semester | |
| niggling issuses | 微不足道的;(不严重却持续不断的)烦人的 |
| being of importance | 很重要 |
| treate this assignment as being of utmost importance | |
| piazza | (尤指意大利城镇中的) 广场; |
Lecture 1, Course Overview
segment 1
| spherical harmonic lighting | 球谐光照 |
| on the faculty of | 职员之一;(院校)系里的成员 |
| graphics image synthesis | |
| rendering | |
| create realistic images | |
| ACM SIGGRAPH | |
| program 3D computer graphics | |
| OpenGL, which is a graphics API | |
| the OpenGL shading language | |
| a real time scene viewer | |
| ray tracing | 光线追踪算法 |
| a little bit of a hint of the kinds of things | |
| collage | 拼贴画;收集品 |
| reflections | 反射 |
| refractions | 折射 |
| glass spheres | 玻璃球 |
| chess boards | |
| initial segment | |
| it's really an intellectually, exciting and challenging field, | |
| Pixar | |
| 1995 Toy Story by Pixar | first completely computer graphics movie |
| Lighting simulation | |
| one very important area in computer graphics | |
| computer graphics is really critical for visualization. | |
| flight simulators | |
| and so forth. | 等等 |
| digital visual media | |
| of which computer graphics is an integral part | |
| 3D geometric models | |
| Visual media are so prevalent | |
| We have Flickr. YouTube. WebGL | |
| Google earth | |
| very realistic flythroughs of the real world. | |
| Electronic publishing | |
| Online gaming | |
| is perhaps the biggest driver of games | |
| 3D printers and fabrication | |
| we are now seeing a vast revolution | |
| print real 3D objects, perhaps with realistic material properties | |
| we can expect to see dramatic advances | |
| new computing methods, new display technologies |
- Lighting simulation lighting simulation is important to create realistic simulations of how the interiors of buildings, interiors of rooms will look. How an automobile will look in an outdoor lighting environment. And computer graphics is used for all of these applications. It can be used for scientific visualization as well as medical visualization.
- future So, what we have seen here is that computer graphics has numerous applications and it involves fundamental intellectual and technical challenges which make it one of the most exciting areas to study and I hope you will join us in this course.
Segement 2, Outline and Logistics
| course logistics | |
|---|---|
| go over some of the course logistics | |
| 3D graphics pipeline. | |
| collaborators | 合作者 |
| humanoid motion | 人形的 |
| vibrant humanoid motion | |
| assignment | 任务 |
| homework | |
| assignment logistics | |
| Logistics | 组织,安排; |
| 后勤 | |
| rasterize | 格栅化,点阵化 |
| raytrace | 光线追踪 |
| workload | 工作量 |
| shaders | |
| programmable shaders | |
| our initial lecture on an overview and history. | |
| was coined by | 由……创造,铸造 |
| a bank of | 一堆…… |
| a bank of LEDs | |
| in the scene | 场面,场景 |
| presages | 预兆 |
| SuperPaint system really presages modern software technologies | |
| alter images by cropping, scaling, compositing them. | |
| add or remove objects. | |
| Sports broadcasts | |
| That's been a quick tour of 2D computer graphics. | |
| Geometric modeling | |
| Geometric modeling is the process of creating 3D geometry, | |
| spline curves and surfaces | 样条曲线 |
| genus | 属,类 |
| spout | (容器的)嘴;水柱 |
3D graphics pipeline he graphics pipeline consists of 3 stages: modeling, animation and rendering.
- Modeling
- creating geometric models of objects
This could be a simple model of an object like a teapot. It could be a complicated mesh of an object like a cat sculpture. Or it could be a 2 billion polygon mesh of Michelangelo's David that was scanned several years ago by Professor Levoy and collaborators.
- Animation
The next step if you want the objects to actually move is to consider the animation or the motion of characters. And this is a rich area. We often want vibrant humanoid motion. In other cases we just want motion of objects from one place to another.
- Rendering
The final step is rendering or creating realistic images, given the geometry and the animation. And there we want to simulate the way the light propagates in the scene to create effects like realistic and intricate shadow details, such as what you see in images on the right.
Assignment or Homework
The first assignment deals with transformations and the goal there to place the objects in the world and view them.
In particular, you will write a simple viewer that will view a teapot placed at the center of the screen and you will have to move around the teapot and create images in that way.
- a simple viewer
there you want to be able to view the scene the user specifies, and you want to be able to do it, with realistic lighting, with realistic materials, and as specified by the user.
- a scene viewer
you will build a ray tracer which is an offline method to create very visually high quality visually realistic images by tracing rays that arise from the camera and go through each pixel in the image.
- a ray tracer
Topics
- I've said "rasterize" and I have said "raytrace."
Rasterization essentially goes through all the geometric primitives and dertermines where in the screen they should go.
Raytracing does the opposite thing which goes to each point or each pixel in the screen and determines which geometric primitive that corresponds to.
- advantages and disadvantages They each have their advantages and disadvantages, namely raytracing can produce higher quality images, but has historically been slower.
应用场景
- textual representations
- GUI
Xerox, 1975
- Drawing
- Ivan Sutherland's sketch pad system, 1960s, at MIT
- pop up menus
- constraint based drawing
hierarchical modeling
- paint systems
- SuperPaint System, Xerox, in the 1970s
Graphics Rendering
in the 1960's the challenge was handling visibility.
I want to eliminate the lines that I cannot see. And this is a challenge in art as well to create images that convey the notion of depth perception.
- hidden line algorithms
hidden line elimination
- hidden surface algorithms
- specular lighting
- 镜面高光
or Phong shading, and Phong illumination and Phong shading,
- Z-Buffer 算法
- Z 缓冲器算法也叫深度缓冲器算法
or the hidden surface algorithm
- Global illumination
- 全域光照
recursive ray-tracing algorithm
- radiosity
the red wall here reflects energy onto the box
Cornell Box
- rendering equation
torus 环形曲面 hidden line elimination. facet 部份 the geometry that's being used to approximate the sphere polygonal outlines matte 不光泽的 they still looked like matte, or clay. diffuse 漫反射的 body color component specular highlight reflections, refractions synopsis 大纲,概要 animation
Lecture 2
Segement 1
| core mathematical ideas | |
| technical ideas | |
| some of the core mathematical and technical ideas |
- books The standard red book for OpenGL, and the orange book for the
GL shading language.
Basic Math
- linear algebra
- vectors
- dot product
cross product
- matrix
matrix-vector and matrix-matrix multiplication
- 应用场景
Assume for example that you have a point that you want to translate to a different region. This comes up all the time, you have a character, you want to move it somewhere else in the scene. You can regard the point as a vector and we'll see how an operation like translation, rotation can be written as a matrix-vector mulitiplication.
Vectors
| vector symbol | they are often written in bold |
|---|---|
| norm symbol | |
| vector addition | |
| parallelogram | 平行四边形 |
| diagonal | 对角线的,斜线的 |
| the diagonal | 对角线 |
| the addition | 和 |
| If you don't want to think in terms of parallelograms | |
| Cartesian component | 笛卡儿分量 |
| Pythagorean relationship | 毕达哥拉斯关系 |
| 即:勾股定理 c^2 = a^2 + b^2 | |
| right-handed coordinates | 右手坐标系 |
- 用途
Vectors are used to store offsets, displacements and locations
- 坐标的英语解说
And you can see in this case, it has 4 units along the X axis and 3 units along the Y axis. (4, 3) —> 4i + 3j
- 右手定则
类似安培的右手定则:四指从 x 轴转向 y 轴,那么大拇指的指向就是 z 轴
向量
模
- magnitude
- the norm of a
- the magnitude of a
用途
offsets, displacements, locations
运算
vector addition
向量加法
| Cartesian Coordinates | 笛卡儿坐标 |
| orthogonal | 正交的,直角的 |
| coordinate system |
vector multiplication
向量乘法
dot product
- 点积
- scalar product
两种运算
- k ・ a, 乘以常数 k
- a ・ b, 两个向量相乘
- 英语说法: a dot b
- 英语说法
| 运算 | 对应 |
|---|---|
| times | 乘以 |
| plus | 加上 |
- a*b + c a times b plus c
- cos<a,b> = (a ・ b)/(||a||・||b||)
应用
- find angle between two vectors (e.g. cosine of angle between light source and surface for shading)
计算两个向量之间的夹角
- find projection of one vector on another (e.g. coordinates of point in ordinary coordinate system).
计算,一个向量在另一个向量上的投影
projection 投影
- 投影
the projection of vector b lies on a. 向量 b 在 a 上的投影
b –> a
- b 在 a 上的投影
b cos<a,b> == a ・ b / a 用小于||a||
- b –> a
b 在 a 上的投影向量
b –> a ・(a / a ) = a ・ b/ a 2 ・ a
cross product
叉积
Orthonormal bases and Coordinate frames
正交基 与 坐标系框架 We use right-handed (standard) coordinates
相关概念
位置矢量
即坐标
切矢量
切线对应的矢量
- 单位切矢量
法矢量
主法矢
在曲线所在平面内侧的法线
副法矢
垂直与 曲线所在平面
法平面
垂直于切线
密切面
即曲线所在平面,过切线
从切面
垂直于密切面,并过切线
曲率
在主法线方向,对于对于弧长的转动率
挠率
在副法线方向,对于对于弧长的转动率
插值
插值曲线
由插入数据点构造的曲线,就是插值曲线
- 线性插值
- 抛物线插值
拟合
光顺
意指,曲线的拐点不能太多
- 注意,说的不是驻点
曲线连续性
相交处连续性 p(i), p(i+1)
参数连续性
相交处
0 阶参数连续性
分段曲线方程,间断点(连接点)数值相等
1 阶参数连续性
曲线段方程,连接点,一阶导数 “也” 相等
2 阶参数连续性
曲线段方程,连接点,一阶二阶导数 “都” 相等
几何连续性
- 要求相对参数连续性,更宽松
- 只要求,在曲线段 “相交处”,参数导数成比例即可
0 阶几何连续性
与 0 阶参数连续性完全一致
注意
- 0 阶,要数值,完全一致
1 阶几何连续性
1 阶导数成比例
2 阶几何连续性
1 阶导数成比例,并且曲率相等
参数化
节点
各个参数值 t0, t1, t2, …
型值点
插值点 p0, p1, p2, …
文章作者
上次更新 2023-02-10 (97c415e)