本教程向朋友们介绍Maya Nurbs 车轮建模的流程，教程介绍的很详细，知识教程是英文教程，感兴趣的朋友可以慢慢阅读一下！
为了让大家更能理解这个教程，我并不翻译其中一些命令，这样可以让一些初学者 ( 不是很熟悉 maya nurbs 建模命令 ) 更快找到这些命令。另：我的英文不好，所以在翻译的时候会有一些不足之处，如果有让你发笑的地方，请你给我提醒，我将更改过来 , 我的 email: chinacache@163.com.
希望可以和大家一同进步！！！！！
打开你的 maya, 切换到 front 视图，创建圆滑的曲线 ( 如 pic 0 所示 ). 在这个教程里我使用厘米作为单位，车轮的直径为 3.927( 如 pic 1), 这个尺寸在 xyz 轴上都是有效的，你可以自己选择你喜欢的尺寸，如 3.9 或 4.
nowselectsecond circle shapes (pic 1a), then surface planar. and then edit nurbs rebuild surfaces, open option box and enter 8x8 for uv spans (pic 2) , this rebuild surface step is important #39;cause we needa high-resolution nurbs for this main front object.
现在选择第二条圆环曲线 (pic 1a), 使用 surface planar 命令 . 然后使用 edit nurbsrebuild 命令重建曲面，改变曲面 uv 度为 8x8(pic 2), 这一点非常重要，因为我们需要一个非常精确的曲面。
from front viewselectthese outer cv#39;s (pic 3) then drag to -z axis (pic 4), -z value its about -0.235. you could expand your cv information on the right panel to see the value.
在 front 视图里选择 cv 点 (pic 3) 将其在 -z 轴方向拉伸 (pic 4), 数值约为 -0.235. 你可以在 channel box 里看到这一数值。
select these 9 center cv#39;s (pic 5) and drag also to -0.235 -z axis (pic 6).
选择 9 个 cv 点 (pic 5) 将其在 -z 轴上拉 -0.235 的距离 (pic 6).
select these oval shapes (pic 7) and drag to about -0.46 of -z axis (pic 8).
选择那些卵形的曲线 (pic 7) ，并在 -z 轴上移动 -0.46(pic 8).
now you have front oval shapes (bigger) and oval back shapes (smaller) right? ok nowselectevery set of oval shapes like in pic 9 and loft them (every set of them), then it would look like this pic (pic10).
先选择大的卵形曲线，按住 shift 键选择小形卵形曲线 (pic 9) ，一组一组的 loft 它们，然后就可得到如下图的结果 (pic 10).
nowselectthe other shapes (triangle and small shapes in the center) (pic 11) and then extrude them to -0.5 of -z axis (pic 12). remember : to extrude a curve as nurbs, open your extrude option box andset the style to distance, and make sure output geometry has been set to nurbs
现在选择其它曲线 ( 三角形和中心那些小圆 )(pic 11), 然后在 -z 轴上 extrude -0.5 的距离 .
记住 : extrude 出来是应该椒 nurbs 曲面，打开你的 extrude 选项，设定距离并确定输出的几何体为 nurbs 曲面 .
before entering this fillet amp; trim work, there is something important that we should know about preview resolution (antialias settings) and tessellation smoothness within maya.
在进入 fillet 及 trim 的工作之前，有一些很重要的事情我们应该了解一下 maya 的镶嵌的圆滑设置 .
most of new maya users are shy of this nurbs gaps that are caused by fillet amp; trim works.
很多的使用 maya 的人都会造成此类现象。
when using nurbs with lots of fillet amp; trim works, it is important to preview the scene with production quality on render globals. even if it#39;s just a preview, production quality has soft multi-pixel filtering. anti-alias is important for nurbs with fillet amp; trim in maya. in this case, i am not talking about rebuilding the surfaces, but we could use smooth anti-alias combined with better tessellation settings to close the gaps.
当你在使用 nurbs 做一些 fillet 和 trim 的工作时，在全局渲染里将预视图设为产品质量 (production quality) 是很重要的 . 虽然它只是预视图，产品质量 (production quality) 可以圆滑缝合点 . 抗锯齿 (anti-alias) 在 maya 里的设置，对 fillet 和 trim nurbs 表面也是同样重要 . 在这种情况下，我不是想说要重建表面，我们可以通过对抗锯齿的设置来改善它 .
ok its about resolution preview, now about the tessellation problem, you can choose one of these 3 optionsorplay around with each settings :
让我们谈谈镶嵌的问题，你可以选择这 3 个选项中的一个或三个都选来设置 :
1. before circular filleting an object, be sure your positional tolerance (in circular fillet option box) has been set to minimal value for better tessellation between two surfaces, you could set it to 0.010 (the default is 0.0100), and also you can change the tangent tolerance to about 0.0100, with this option and value, maya will create more tightconnection between two surfaces.
1. 在 circular fillet 物体前，确认你的 positional tolerance( 在 circular fillet 选项里 ) 是否已经设置到最小的值，以便在两个要 fillet 的曲面中得到最好的结果，你可以设为 0.010( 缺省就是 0.010), 同样你也可以将 tangent tolerance 设为 0.0100, 在这种设置下， maya 可以在严谨的连接两个曲面 .
2. maya has built-in automatic nurbs tessellation check located in the render menu. if you want to render your nurbs scene, all you have todo isselectall of your nurbs objects, go to the render menu andselectset nurbs tessellation, apply this function, then render the scene, it will reduce the gaps automatically. this feature evaluates a set frame (s) and automatically determines the optimum tessellation settings, which results in smoother surfaces without over-tessellation (of course this saves time and memory).
2.maya 会自动创建 nurbs 曲面的镶嵌，你可以在 render menu 里查看它 . 如果你想渲染你的 nurbs 场景，你必需要做的是选择你所有的 nurbs 物体，到你的 render menu 里设置 nurbs 镶嵌，然后渲染场景，它可以减少缝隙 . 它会增加你的渲染时间和内存，但是可以使你的曲面平滑 .
3. every time you#39;re finished with fillet amp; trim,selectyourtrimmed amp; filleted objects and set/turn on advanced tessellation andset number of uv to 20x20 (pic 14), and again, don#39;t forget to set your render globals to production quality. it doesn#39;t have to be 20x20, but i have found these to be good settings, but be carefull with this settings, the surfaces would very very smooth which increasing yourrendering times.
3. 当你每次完成 fillet 和 trim 操作，选择已被 fillet 和 trim 过的物体设置它们的 advanced tessllation 属性，将 uv 设为 20x20(pic 14), 不要忘记在全局渲染里设置产品质量 . 虽然不一定要到 20x20, 但是我认为这是