Blender 3D:各种各样的教程

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Specular reflection , or  regular reflection , is the  mirror -like  reflection  of  waves , such as  light , from a  surface . ^[1]
::镜反射或正则反射是波的镜像反射,例如光,从表面. [1]

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The  law of reflection  states that a reflected  ray  of light emerges from the reflecting surface at the same  angle  to the  surface normal  as the incident ray, but on the opposing side of the surface normal in the plane formed by the incident and reflected rays. This behavior was first described by  Hero of Alexandria  ( AD  c. 10–70). ^[2]  Later,  Alhazen  gave a complete statement of the law of reflection. ^{[3] [4] [5]}  He was first to state that the incident ray, the reflected ray, and the normal to the surface all lie in a same plane perpendicular to reflecting plane. ^{[6] [7]}
::反射定律指出,反射的光线从反射表面以与发生射线相同的角度与表面正常出现,但在发生射线和反射射线形成的平面中,在表面正常的对面.这种行为首先由亚历山大英雄 (公元1070) 描述. [1] 后来,阿尔哈森对反射定律做了完整的陈述. [2] [3] [4] 他首先指出,发生射线,反射射线和表面正常都位于与反射平面垂直的同一平面中.

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Specular reflection may be contrasted with  diffuse reflection , in which light is scattered away from the surface in a range of directions.
::镜面反射与散射反射相对比,在这种反射中,光从表面分散在一系列方向上.

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When light encounters a boundary of a material, it is affected by the optical and electronic response functions of the material to electromagnetic waves. Optical processes, which comprise  reflection  and  refraction , are expressed by the difference of the refractive index on both sides of the boundary, whereas  reflectance  and  absorption  are the real and imaginary parts of the response due to the  electronic structure  of the material. ^[8]  The degree of participation of each of these processes in the transmission is a function of the frequency, or wavelength, of the light, its polarization, and its angle of incidence. In general, reflection increases with increasing angle of incidence, and with increasing absorptivity at the boundary. The  Fresnel equations  describe the physics at the optical boundary.
::当光遇到材料的边界时,它受到材料对电磁波的光学和电子反应功能的影响.光学过程,包括反射和折射,通过边界两侧的折射率差异来表达,而反射率和吸收是由于材料的电子结构而导致的反应的真实和虚构部分. [1] 这些过程在传输中的参与程度是光的频率或波长,其偏振和其发生角度的函数.一般来说,反射随着降射角度的增加,以及在边界的吸收率的增加而增加.弗雷内尔方程描述了光学边界的物理.

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Reflection may occur as specular, or mirror-like, reflection and  diffuse reflection . Specular reflection reflects all light which arrives from a given direction at the same angle, whereas diffuse reflection reflects light in a broad range of directions. The distinction may be illustrated with surfaces coated with  glossy   paint  and  matte  paint. Matte paints exhibit essentially complete diffuse reflection, while glossy paints show a larger component of specular behavior. A surface built from a non-absorbing powder, such as plaster, can be a nearly perfect diffuser, whereas polished metallic objects can specularly reflect light very efficiently. The reflecting material of mirrors is usually aluminum or silver.
::反射可以是镜面或镜像反射和散射反射.镜面反射反射来自特定方向的光线在相同的角度,而散射反射反射光线在广泛的方向.区别可以用涂有光泽涂料和色涂料的表面来说明.色涂料基本上显示完全的散射反射,而光泽涂料显示更大的镜面行为组成部分.用不吸收粉末制成的表面,如石膏,可以成为一个几乎完美的散射器,而抛光的金属物体可以非常有效地反射光线.镜子的反射材料通常是或银.

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Light propagates in space as a wave front of electromagnetic fields. A ray of light is characterized by the direction normal to the wave front ( wave normal ). When a ray encounters a surface, the angle that the wave normal makes with respect to the  surface normal  is called the  angle of incidence  and the plane defined by both directions is the  plane of incidence . Reflection of the incident ray also occurs in the plane of incidence.
::光在空间中以电磁场的波面传播.光线的特征是波面的正向 (波正向).当光线遇到表面时,波正向与表面正向所形成的角度称为冲击角,两个方向所定义的平面是冲击平面.冲击射线的反射也发生在冲击平面中.

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The law of reflection states that the angle of reflection of a ray equals the angle of incidence, and that the incident direction, the surface normal, and the reflected direction are  coplanar .
::反射定律指出,射线的反射角等于射入角,且撞击方向,表面正常和反射方向是共平面的.

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When the light is incident perpendicularly to the surface, it is reflected straight back in the source direction.
::当光垂直地落在表面时,它会直接反射回源方向.

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The phenomenon of reflection arises from the  diffraction  of a plane wave on a flat boundary. When the boundary size is much larger than the  wavelength , then the electromagnetic fields at the boundary are oscillating exactly in phase only for the specular direction.
::反射现象是由于平面波在平面边界上的衍射而产生的.当边界大小大于波长时,边界的电磁场仅在光谱方向上正确的相位振动.

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The law of reflection can also be equivalently expressed using  linear algebra . The direction of a reflected ray is determined by the vector of incidence and the  surface normal  vector. Given an incident direction  ${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{i}}}$  from the light source to the surface and the surface normal direction  ${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}},}$  the specularly reflected direction  ${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{s}}}$  (all  unit vectors ) is: ^{[9] [10]}
::反射定律也可以用线性代数等效地表达.反射射线的方向由发生向量和表面正常向量决定.从光源到表面的发生方向d ^ i和表面正常方向d ^ n,光谱反射方向d ^ s (所有单位向量) 是:[9][10]

${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{s}}={\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{i}}-2{\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}\left({\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}\cdot {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{i}}\right),}$

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where  ${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}\cdot {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{i}}}$  is a scalar obtained with the  dot product . Different authors may define the incident and reflection directions with  different signs . Assuming these  Euclidean vectors  are represented in  column form , the equation can be equivalently expressed as a matrix-vector multiplication: ^[11]
::在这里,d ^ n ⋅ d ^ i 是用点积得到的标量.不同的作者可以用不同的符号定义发生和反射方向.假设这些欧几里德向量以列形式表示,则可以将方程等同地表示为矩阵向量乘法: [1]

${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{s}}=\mathbf{R}{\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{i}},}$

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where  ${\displaystyle \mathbf{R}}$  is the so-called  Householder transformation matrix , defined as:
::其中R是所谓的"房主转换矩阵",定义为:

${\displaystyle \mathbf{R}=\mathbf{I}-2{\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}{\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}^{\mathrm{T}};}$

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in terms of the  identity matrix   ${\displaystyle \mathbf{I}}$  and twice the  outer product  of  ${\displaystyle {\stackrel{\mathbf{^}}{\mathbf{d}}}_{\mathrm{n}}}$ .
::在等式矩阵I和d^n的外乘倍数的条件下.

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Reflectivity  is the ratio of the power of the reflected wave to that of the incident wave. It is a function of the wavelength of radiation, and is related to the refractive index of the material as expressed by  Fresnel's equations . ^[12]  In regions of the electromagnetic spectrum in which absorption by the material is significant, it is related to the electronic absorption spectrum through the imaginary component of the complex refractive index. The electronic absorption spectrum of an opaque material, which is difficult or impossible to measure directly, may therefore be indirectly determined from the reflection spectrum by a  Kramers-Kronig transform . The polarization of the reflected light depends on the symmetry of the arrangement of the incident probing light with respect to the absorbing transitions dipole moments in the material.
::反射率是反射波与入射波的功率的比率.它是辐射的波长的函数,与弗雷内尔方程表达的材料的折射率有关. 在材料吸收显著的电磁谱区域,它通过复杂的折射率的虚构组成部分与电子吸收光谱有关.因此,难以或不可能直接测量的不透明材料的电子吸收光谱可以通过克拉默斯-基格朗变换从反射光谱中间接确定.反射光的偏振取决于探测入射光与吸收物质中的二极转换时刻的对称性.

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Measurement of specular reflection is performed with normal or varying incidence reflection spectrophotometers ( reflectometer ) using a scanning variable-wavelength light source. Lower quality measurements using a  glossmeter  quantify the glossy appearance of a surface in  gloss units .
::镜面反射的测量是使用正常或变频反射光谱仪 (反射仪) 进行的,使用扫描变波长光源.使用光泽计的低质量测量量表在光泽单位中量化表面的光泽外观.

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When light is propagating in a material and strikes an interface with a material of lower  index of refraction , some of the light is reflected. If the angle of incidence is greater than the  critical angle ,  total internal reflection  occurs: all of the light is reflected. The critical angle can be shown to be given by
::当光在材料中传播并与折射率较低的材料碰撞时,部分光会反射.如果射角大于临界角,则会发生全内反射:所有的光都会反射.临界角可以通过

${\displaystyle {\theta }_{\text{crit}}=\arcsin \left(\frac{n_2}{n_1}\right).}$

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When light strikes an interface between two materials, the reflected light is generally partially  polarized . However, if the light strikes the interface at  Brewster's angle , the reflected light is  completely  linearly polarized parallel to the interface. Brewster's angle is given by
::当光撞击两个材料之间的接口时,反射光通常是部分偏振的.然而,如果光在布鲁斯特角度撞击接口,反射光完全是线性偏振平行于接口.布鲁斯特角度是

${\displaystyle {\theta }_{\mathrm{B}}=\arctan \left(\frac{n_2}{n_1}\right).}$

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The image in a flat mirror has these features:
::面镜中的图像有以下特征:

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• It is the same distance behind the mirror as the object is in front.
  ::镜子后面的距离与镜子前面的距离相同.
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• It is the same size as the object.
  ::它与物体的尺寸相同.
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• It is the right way up (erect).
  ::这是一条正确的道路.
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• It is reversed.
  ::现在是逆转的.
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• It is  virtual , meaning that the image appears to be behind the mirror, and cannot be projected onto a screen.
  ::它是虚拟的, 意思是图像似乎在镜子后面, 不能投射到屏幕上.

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The reversal of images by a plane mirror is perceived differently depending on the circumstances. In many cases, the image in a mirror appears to be reversed from left to right. If a flat mirror is mounted on the ceiling it can appear to reverse  up  and  down  if a person stands under it and looks up at it. Similarly a car turning  left  will still appear to be turning  left  in the rear view mirror for the driver of a car in front of it. The reversal of directions, or lack thereof, depends on how the directions are defined. More specifically a mirror changes the  handedness  of the coordinate system, one axis of the coordinate system appears to be reversed, and the  chirality  of the image may change. For example, the image of a right shoe will look like a left shoe.
::图像的反转由平面镜来看是不同的,取决于情况.在许多情况下,镜中的图像似乎是从左到右的反转.如果一个平面镜安装在天花板上,如果一个人站在它的下面,看起来会反转上下.同样,车向左转的车辆仍然会在前面的车辆的驾驶员的后视镜中看起来是左转.方向的反转或缺乏,取决于方向的定义.更具体地说,镜子改变了坐标系统的手性,坐标系统的轴之一似乎是反转的,图像的奇拉性可能会改变.例如,右鞋的图像看起来像左鞋.

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A classic example of specular reflection is a  mirror , which is specifically designed for specular reflection.
::镜子是反射的典型例子,它是专门为反射而设计的.

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In addition to  visible light , specular reflection can be observed in the  ionospheric reflection  of  radiowaves  and the reflection of radio- or  microwave   radar  signals by flying objects. The measurement technique of  x-ray reflectivity  exploits specular reflectivity to study thin films and interfaces with sub-nanometer resolution, using either modern laboratory sources or  synchrotron  x-rays.
::除可见光外,还可以观察到射线的离子层反射和飞行物体反射的无线电或微波雷达信号.X射线反射的测量技术利用光谱反射来研究薄膜和具有亚纳米分辨率的接口,使用现代实验室来源或同步射线.

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Non-electromagnetic waves can also exhibit specular reflection, as in  acoustic mirrors  which reflect sound, and  atomic mirrors , which reflect neutral  atoms . For the efficient reflection of atoms from a  solid-state  mirror, very cold atoms and/or  grazing incidence  are used in order to provide significant  quantum reflection ;  ridged mirrors  are used to enhance the specular reflection of atoms.  Neutron reflectometry  uses specular reflection to study material surfaces and thin film interfaces in an analogous fashion to x-ray reflectivity.
::非电磁波也可以表现出镜面反射,如反射声音的声镜和反射中性原子的原子镜.为了有效地反射原子,从固态镜中使用非常冷的原子和/或放牧发生,以提供显著的量子反射;用状镜来增强原子的镜面反射.中子反射计使用镜面反射来研究材料表面和薄膜接口,类似于X射线反射.