_Vray摄影棚照明.doc

Vray中的摄影棚照明(Studio Lighting in Vray)In this tutorial i will tell you the method of studio lighting. For the rendering i used Vray 1.5rc3, the latest version of the program. This famous chair called Corbusier was modeled in 3ds max 9. With the knowledge of this tutorial you will be able to present your models in a more ambitious way than before. ;)在这个文章里面,我将对摄影棚照明方法作一个讲解.这里我是用来渲染的是Vray 1.5rc3,最新版的Vray.这个著名的椅子叫做柯布西耶(Corbusier),是在3ds max 9里建的.在看完这个文章之后,你将可以使用比以前更好的方法来表现你的模型.;)The main parts of the tutorial are : Making the environment Placing the lights Setting up Vray for tests Shaders Setting up Vray for final rendering Postwork in Photoshop这是本文章的主要部分: 创建环境 放置灯光 Vray的测试设置 材质 Vray的渲染设置 PS后期处理Making The EnvironmentThe environment is pretty much simple. Place a plane under the model and set 3 for the Length segments and set 2 for the Width segments.Convert it to editable poly with right click on the plane and choosing convert to:. The next step is selecting the two edges behind the chair and pull them up while pressing the shift button. With this way create a shape around the model like in the third picture.创建环境这里设置的环境非常简单.在模型下面放置一个平面,将长度段数(Length segments)设置为3,宽度段数(Width segments)设置为2.在平面上右键并在菜单中选择convert to .将其转换为可编辑多边形(editable poly).接着选择椅子后面的两条边,配合shift键将它们拉起来,这样就将它做成下图的形状.We will use a Turbosmooth modofier on the plane, but to controll the way of smoothing we have to chamfer a few edges before.我们将要给这个平面增加一个Turbosmooth修改器,但是在增加之前要对其中一些边进行切角(chamfer).Now we are able to use the turbosmooth with 2 Iterations.现在我们可以给平面增加Turbosmooth修改器并将它的Iterations参数设置为2.Placing the LightsThis topic is the heart of the studio lighting. We will use 3 vray lights with different strength,postion and color. This three attribute will determine the mood and the individuality of youre render. So place a vray light from left view, with the given settings.放置灯光这部分是摄影棚照明的核心.我们将使用3个不同强度,不同位置和不同颜色的VR灯光.这三个特性是由你的心情和渲染风格来决定的.在左边放置一个VR灯光,设置如图.Now change to top view ,copy the light and mirror it to the X axle. Place it to the right side of the plane and use the given settings. The third light will be placed later, after the test renderings.现在来到顶视图(Top view),将这个VR灯以X轴进行镜像复制.放它到平面的右边,并按下图的参数设置.第3个灯稍后在测试后再放.Create a Target Camera from top view with 35mm lens, and set it up as you see.在顶视图里创建一个摄像机,焦距(lens)设置为35mm,并像下图那样放置.All right, choose vray as youre primary renderer. Make a vray material with a light grey diffuse color, R:170/G:170/B:170. Put this material to the override mtl slot in the Global Switches tab.现在将vray设置为当前渲染器.创建一个颜色为R:170/G:170/B:170中度灰色的vray材质.将它放到全局切换(Globle Switches)下的替代材质(override mtl).Now all the objects in the scene will have this material, so this function is great to test lighting with a clay render. Later we will turn this function off. Hit F9 and lets see what we got here.这是在没有做任何设置的情况下我们所得到的结果.没有间接照明和任何采样,除了默认的.现在我们需要对vray进行设置来做测试渲染.来看下一部分.现在场景中所有物体都有这个材质了,这个功能对测试灯光是非常好的.等下会将把它关掉.按F9来看看测试结果.So this is what we have without any settings. No illumination,or any kind of sampling except the standard one. Now we need to set up vray for test renderings. It is time to move to the next topic.Setting up Vray for Tests To test the illumination in the scene we need to set up vray with low values. These are only tests ,so we only want a quick feedback from the lighting. First of all change the image aspect ratio to 1.8 in the Common tab. Go to camera view and turn on the Safe Frame option. Safe Frame will help you to place your camera to the right position and it is also helps to notice unwanted parts in the view.Vray的测试设置我们需要对vray设置较低的参数来对场景的灯光进行测试.这仅仅是测试,所以我们仅仅需要灯光的一个快速的反馈.首先,在Common选项卡中将图像的高宽比(aspect ratio)设置为1.8.在摄像机视图中打开安全框(Safe Frame)选项.安全框可以帮助你将摄像机放置到一个合适的位置,同样可以帮助你设置视图中不需要的部分.Now here comes the capital part of the Renderer tab settings.这里是Render选项卡的设置.Here is a short explanation of the test settings: Default lights: turn it off ,we do not want any light, except the vray ones. Adaptive QMC: A faster image sampling method than Adaptive subdivision. Mitchell-Netravali: With this antialiasing filter edges will be sharp but not crisp. Irradiance map + Light cache: the mostly used GI combination. HSph subdiv: (GI samples) lower it to speed up the rendering process. Show calc phase: The rendering process will be visualized, so if are not happy with the effect you dont have to wait until the effective rendering. Subdivision: The subdiv. of lightcache controls the number of traced paths. The actual number of the traced paths is the square of the adjusted number.So with 500subdiv. 250.000 paths will be traced. Exponential: With this type of colormapping ,colors will be saturated so you can avoid burnouts on the surfaces. Dark multiplier: This controls the Sternth or the multiplier of dark colors. Render region division: set it to 32x32 ,smaller bucket size less ram will needed with smaller bucket size a faster feedback can be achieved. All right, lets see the render with the mentioned settings. 这里是对这些测试设置的简单解释: Default lights:把它关掉,除了VR灯光外,我们不需要其他灯光. Adaptive QMC:相对于自适应细分(Adaptive subdivision)来说,这是较快的图像采样器. Mitchell-Netravali:用这个抗锯齿过滤器,物体的边缘会锐利而不会太过. Irradiance map + Light cache:最常用的GI组合. HSph subdiv:降低它的数值,加快测试的速度. Show calc phase:让渲染计算可以看到,可以根据你的喜好设置. Subdivision:控制lightcache的追踪路径的数量.追踪路径的实际数量是这个数值的平方.所以500的subdivs值就表示250000个追踪路径. Exponential:用这个色彩映射方式,可以保持颜色和避免物体表面的暴光. Dark multiplier:控制暗部颜色倍增. Render region division:设置为32x32,渲染格越小内存占用越少,小的渲染格可以得到更快的渲染反馈. 好的,让我们看看这个设置的测试结果.It is much better than the first one. The scene is much more brighter, light is smoother and there are no burnouts. Because of the low quality settings there are GI artifacts ,noise and blurry lines. However ,these settings provide us a very efficent way of testing. Lets play with the colors to break the dull feeling of the render. Change the color of the vray light on the right to R:255/G:180/B:80. This warm orange color will take care of the monotonic lighting.这比第一次测试好很多了.场景亮多了,光线更加柔和而且没什么暴的地方.因为质量低,所以会有漏光,噪点和模糊的线.但是,这个设置可以给我们提供一个非常快的测试方法.让我们改一下灯光的颜色,打破渲染的单调感.将右边的灯的颜色改成R:255/G:180/B:80.这是一个暖的橙色,让灯光不再单调.At this point if you are satisfied with the result you can go to the next step. Creating and understanding shaders is the following topic.在这里,如果你对这个结果满意的话就可以往下一步了.在跟着的部分里,将创建材质并对其进行理解.ShadersIn this scene i used four or five shaders. Plasctic,Chrome,Leather,White fabric, and the white background of course. Turn off the override mtl function in the Global Switches tab. Lets take a quick look at the settings.材质在这个场景里我用四到五个材质.塑料(plasctic),不锈钢(chrome),皮革(leather),白布(white fabric),和白色背景(white background).在全局切换(global switches)里将override mtl关掉.来看一个材质的设置. Diffuse: This controls the color of the material. Reflect: Pure white means 100%reflections ,black means 0% reflections. Refl. Glossiness: Controls the blurryness of reflection 1 means perfect mirror-like reflections, lower values produce blurry reflections. Subdivision: This controls the quality of glossy reflections, higher values increase rendertime lower values produce noisy effect. For testing /5-8/ final rendering /15-35 or higher if necesarry/. Freshnel reflections: If you check it that means the strength of the reflection will depend on the viewing angle of the surface. In nature water and glass is reflecting in this manner. The strength of the reflection depends on the Freshnel IOR too. All right lets see the shaders in action.:) Diffuse:控制材质的颜色. Reflect:纯白色表示完全反射,黑色表示无反射. Refl.Glossiness:控制反射的模糊程度.1表示没有模糊反射,较低的数值反射越模糊. Subdivsion:控制模糊反射的质量,较高的数值将增加较多的渲染时间,较低的数值可以产生一个粗糙的效果.一般测试时取58,最终渲染时取1535或更高. Fresnel reflections:如果勾选此项,反射的强度就因视线与物体表面夹角的变化而变化.现实中,玻璃和水的反射就属于这一类.反射的强度也取决于Fresnel IOR的大小.好的,来看看渲染结果.I am pretty happy with the reflections on the leather material. I only need a little more light from above the chair, so lets put that third vraylight to its place.我对皮革材质的反射感到非常满意.我仅仅需要在椅子上多一点灯光,那让我们放第3个灯.It is important to uncheck the Affect Specular slot, we dont want any specular reflection from that light ,only diffuse light.这里需要注意的是取消Affect Specular的勾选,我们不需要从这个灯上获得任何高光反射,仅仅需要一个漫反射的灯.As we can see the bounced light reaches to the bottom of the chair too. Now the lighting and the shaders are finished so lets move on to the next topic. I will discuss the settings of the final rendering.可以看到,反弹光线把椅子的底部也照亮了.现在灯光和材质都完成了,来下一部分.我将说一下最终渲染的设置.Setting up Vray for Final Rendering At this point of the workflow it is very important to find the balance between speed an quality. I will talk about the settings globaly, because some problems cant be solved with only changing the value of an option. So lets see the Renderer tab in this light:)Vray的渲染设置这个工作流的要点,就是要找到质量和速度的平衡,这是非常重要的.我将大概说一下这些设置,因为有些问题不是改一个参数就能解决的.来看一下设置.:)-Change the resoultion to 900x500 -Set the Adaptive rQMC image samplers min dubdiv to 2.Now thinner lines can be rendered correctly. -Change the preset of the Irradiance map to Medium from Low.Set 50 to the HSph subdiv to achive higher quality GI. -Use value 1200 for the Light cache subdiv.Change the Sample size to 0,006 ,now small details will be more visible. Use value 1000 to the Pre-filter option to reduce noise.We have a lot of glossi rays so check the Use light cache for glossi rays option./it will speed up rendering/ For the Filter use the None possibility. -At the rQMC sampler use value 0,005 for noise treshold. Set the Global subdivs multiplier to 4 ,it will increase samling quality everywhere in the scene. -You can find the Light properties in SystemLights settings. Changing the diffuse subdivision of the lights wil effect the number of the traced photons.-Change all the vraylights subdivison to 15 or 20 to avoid noisy parts. -Change all the materials subdivs to 20 in the Reflection section. With these settings the rendertime will increase a lot according to test render settings. Now hit F9 and wait until the calculation finishes.-将图像大小改为900x500-将自适应QMC(Adaptive QMC)图像采样器(image samplers)的min subdivs改为2,现在较细的线可以得到正确的渲染.-将Irradiance map的设置从Low改到Medium.将Hsph.subdivs改回50,以获得更高质量的GI.-将Light cache的subdivs改为1200,Sample size改到0.006,现在细小的细节就更加可见了.在Pre-filter里使用1000的数值来减少噪波.这里有非常多的模糊光线,所以勾取Use light