lsp520520 发表于 2007-6-5 14:43:22

VR入门必读

1:请下载最新版本,可以解决无法贴图问题
下载地址: http://www.downsky.net/ut/attach/143721-VRay0.10.01122601.zip。
http://www.51cad.com

2:将.....40.DLL文件拷贝到3DMAX下,将.....40.DLR文件拷贝到PLUES
下就可使用。

注意 这个插件好像设置了使用期限,过期后将日期调回去应该可以使用,但后面的版本我就不知道开发人员会不会加什么秘密武器在里面了,我的日期是在之前所有版本的限时快到时调到2000年的,所以一直都没出什么问题,呵呵!

二 v-ray简单入门

1、建立场景,(怎样的场景不用我多说了,看书吧。)认为材质和摄影角度满意后,在菜单Customize\\preferences\\Rendering\\Current Renderer中将渲染器设为 vray,这一步骤和mental ray渲染器的设法是一样。

2、在渲染菜单中,在indirect illmination(GI)下,勾选On, 就可以渲染出最简单的GI效果来。

3、是不是发现物体边缘有很多锯齿边?下边再勾选Image sampler(Anti-aliasing)中的
Simple two-level。

全局照的设置过程就这么简单,刚才我所做的渲染过程也就两分钟,但是速度还和一大堆
设置有关,速度时间的弹性也很大,以上我都基本上用默认的数值。
还有一个Multiplier数值要注意,它控制着二级照明强度,将它调大场景也许会更亮,
但不要和灯光强度概念混淆了。

4、 VRAY的渲染参数面板中, 有一个环境Environment, 只有两项
一个是Environent color(环境颜色)选项 ,它的作用mental ray、FR的环境色一样
一个是环境贴图以及强度设置。
   从功能上来说,它是取代MAX自身参数的,最重要的作用应该是用来支持简化的HDR方式,就象FR渲染器一样,可以设置环境贴图的照明强度。
要得到天空光效果也很容易,打开G I后,在MAX环境菜单中把缺省的黑色改成一个兰灰色,或者给它一个球形环境贴图这样我们就打开了全局照明, 渲 一遍试试

注意:1. vray对max本身的环境色、背景不敏感。将场景中的灯 光Exclude掉所有物体,勾选Environent color下的Override MAX'S选项,将颜色设为阳光色再渲一次,(渲染之前记得在场景中将\"天窗\"打开)结果如图5所示。
2. VRAY对于渲染的视图有严格的要求,它必须是在有透视的视图中才能渲染,比如。透视视窗,摄影机视窗。对于T、B、R、L、  S、K、F、U 这一类,没有透视的视窗是什么也不会渲染的。
过程就这么简单,但经验还要慢慢陪养哟。
v-ray 入门(1)--全局光照明
我个人的理解,vray在不打开gi的情况下与好像与max扫描线渲染器差不多,打开gi, 有两种方式急性全局光照,
1) 直接计算,速度极慢,但gi光照效果准确
Direct GI computation produces much more detailed images than the irradiance map; in addition it does not produce flickering in animations. For highly detailed geometry (like the one below) it will produce much more pleasing (but very slow) results. For example the attached picture rendered in 2 and a half hours (mostly because there is a HDRI map in VRay's environment slot, which needed a lot of samples to remove the noise). If you are ready to accept longer render times - by all means use direct GI
1) 模拟计算,在原渲染结果上附加一层光照贴图(vray快速gi的秘诀),
附加方式有三种, (见vray附带说明书 )根据我的初步试验及理解,它好像不能改变原渲染器渲染的最亮部分,而是在原渲染的结果上附加了gi的效果.

全局参数的设置:
1. Max rate 参数与Min rate参数
我的理解: 此值表现光线的层次分布
将屏幕分成一个各小区, 光线在此分布, 设置越高, 光线层次,
光线过渡越光滑,自然,越明显

1 ) Vray在计算光照贴图时, 将场景细分成一个个基本正方形, 每个正方形的顶点都有一个颜色, 如果你定义一个顶点为蓝色,另一个顶点为红色,那么他们之间将是用蓝色到红色的平滑渐变 , 光照贴图正是用顶点颜色来表达灯光效果的, vray通过细分模型的面来达到提高精细度的目的,您可以在光能传莶问?翱诶纯刂葡阜值某潭?

2) Min rate 参数控制细分的最小值.
Max rate 参数控制着开始细分计算正方形的大小
渲染计算时渲染窗口中会出现一个个小方块对场景进行细分,刚开始出现小方块的大小与Max rate的值相关,其值越小方块越大,花的时间越短. 第二遍细分计算方块会更小
最后一遍计算时的方块大小由Min rate决定
Min rate 主要
一般来说,模拟计算gi 时渲染时间主要花在光照贴图的计算上了,计算遍数或者说几幅光照贴图 =(max rate值-min rate值 +1),

计算遍数或者说几幅光照贴图 =(max rate值-min rate值 +1) , 越多
效果就越好 也就是说 max/min 为 -9 / -2 时, 效果比 max/min -3/-2好

2 其它参数
Hsph subdivs: 计算gi时的采样值,与定义值为15,加大它肯定会增加渲染时间,但增加的不多, Hspr细分值 默认为15,到25~30为佳,再大也会像b razil一样了…………
注意此值表现材质及贴图的细腻程度, 光滑程度

Clr thershold Normr thershold
根据 vray原作者的回答:

that's it. Lowering these parameters will make irradiance map calculations longer, but will capture GI detail better

Personally I don't ajust these settings, But I guess if they are set to high, you start loosing detajl, and if to low, it needs more subdivs (time) to render smooth?.

There is something about the detail which is lost (small objetcs such as the horizontal
elements on the wall seem a bit flat. I've read that by reducing the Normal thresh that can
become better

Interp. Samples: 40
(此值为光照贴图加入原渲染结果的精度,可设大一点,不太影响渲染时间)
此值太大 ,softing in surfaces, 一般 40即可
Secondary bounces: subd: 1, depth: 3
(注意:为达到良好的gi效果,最好不要关掉第二级反弹,节约时间的关键在于 max min 的值及光照贴图的幅数)也不要轻易的动原设定值。)depth大一点,这样, 渲染的细节就会多一点
As for sec. bounce subdivision parameter, I think it controls the sampling of the secondary bounces, that is the higher this number is the less noisy the image.
Depth 控制光线反射 ,反弹的次数, 一般场景不超过 5
假如是玻璃, 应该大一点.

关于灯光 一次反弹与二次反弹的?uliplier值问题 
1、非封闭空间,由于没有很多物体做光线的反射,缺省的一次、二次反弹值都是一样的,这样可以弥补空间散失的反射光线。
    可以出效果,但是觉得这样的效果很平淡。(建议不要这样用。)
  
2、非封闭空间,可以利用环境贴图做为补充照明,所以要把二次反弹值减小。(建议这样用)要点是把环境贴图和二次反弹值
    联合在一起考虑。
  
3、封闭空间,环境贴图已经不起作用了,但是物体已经可以形成足够的二次照明,所以如果还是用缺省的值,二次反弹就会太亮,灯光布置足够多的时候,连一次反弹都会太亮。所以我的习惯是灯光亮度、一次反弹、二次反弹的值呈降幂排列比如:
1. 2\\0.8\\0.5。
也可用 0.7\\0.7\\0.5

灯光参数的意义
On - should be obvious

Double-sided - this has effect only on planar maps. It will make them cast light on both sides.
两面都发光。

Transparent - when this is on, the light will not be visible, but will cast light. This can be very useful for interior scenes - you can put transparent lights at the windows, instead of counting just on skylight.
不选中时,灯是可见的。选中时,灯不可见,可以用来模拟天光,窗口的进光

Ingore light normals - by default VRay takes in account the angle between a shadow ray and the light. This produces a noisy image, even in areas that are completely lit (not in shadow). Turning this option on will make VRay ignore this angle and will make the image less noisy (but not physically correct).
默认状态下,vray...(此处不明),这将产生麻点,即使在完全不在阴影中的区域内。勾选中后vray将不考虑这种这种地方,麻点会少点,(但物理上是不正确的)

No decay - by default VRay lights become weaker as the distance from them increases - this is how lights behave in the real world. However, it may not be very convenient to work with. Turning this option on will cause VRay to ignore this distance. You will probably have to adjust the Multiplier if you change this option. Also, it seems that using it causes some artifacts which we will try to fix.
不衰减

Store with irradiance map - this option allows you to store the diffuse illumination from a VRay light in the irradiance map. It may be useful in fly-through animations.
与光照贴图一起保存,对游历动画很有用。

Type and Size I think are clear, with the exception of W size - currently it does nothing, since the two supported types need at most two dimensional parameters.

Subdivs - this controls the quality (graininess) of the shadows. Greater values will produce smoother shadows. The parameter determines the number of samples (per pixel) that VRay will make in order to calculate the shadows (actually, this parameter is the square of the number of samples). VRay may send less (but never more) shadow rays when possible without loss in visual quality.
控制阴影的质量。大点会光滑一点。与采样值的平方成正比。

Low subdivs - this is used instead of Subdivs for irradiance map calculations and also when the level of a ray becomes greater than the degrade depth (see below). Each intersection of a ray with a surface increases its ray level by one. For example reflections typically increase the level of a ray by one, and refractions - by two, since the ray needs to pass through the front and the back surface of the refractive objects.
这个看不懂,呵呵。

Degrade depth - this is the ray level after which Low subdivs will be used instead of Subdivs. In the recent version of VRay, sampling is to a large extent handled automatically, so you can set this to a large value without performance loss.

lsp520520 发表于 2007-6-5 14:44:00

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