本教程是由cmiVFX机构出品的Houdini中可变方向的粒子教程，教程使用软件：Houdini，MP4视频格式，作者：Martin Sawtell，语言：英语。

在本教学中我们将学习一个在实际电影工业特效制作过程中被证明可行的方法，这个新的技术能够在常用的粒子控制系统不起作用的情况下被正常使用。很多教学在粒子被生成后就结束了。Martin将告诉大家在仿真运算完成以后粒子可以用来做什么，他为大家介绍了一种典型的方式，那就是将粒子特效的结果给到合成团队，用于进一步的修饰。通过本教学你将学习到一个视觉特效专家所需要掌握的知识，还有如何在最终期限前得到完美的结果。

Houdini 是一个特效方面非常强大的软件。许多电影特效都是由它完成：指环王中“甘道夫”放的那些“魔法礼花”，还有“水马”冲垮“戒灵”的场面，后天中的龙卷风等等，a52的汽车广告，反正只要是涉及DD公司制作的好莱坞一线大片，几乎都会有Houdini参与和应用。

Houdini不光只适用于视觉特效的制作，随着HOUDINI适用于各种平台，并且出现了很多的HOUDINI培训教学，HOUDINI开始进入了动态图像设计领域****。因为其自身的流程化特性，加上其强大的动力学系统，让HOUDINI在数据可视化方面占有一席重要的地位，让图形设计师能够通过它表达自己的观点。

cmiVFX Houdini Directable Particles

cmiVFX has released their newest lesson offering another glimpse into magical world of visual effects. The flows of power are often visualized with streamers of light chaotically traversing across the scene. How does one create chaos but also maintain the control a director will require? In this lesson we will teach one way this is done in a production environment. The workflow offered here is tested and proven effective within the film industry. This new, exclusive effect technique can succeed in scenarios where conventional particle control systems fail. Additionally, many lessons stop with mere particles in place. Martin Sawtell will teach you one way in which those particles may be used after the simulation is done. Martin answers the question, "Particles are simmed, now what?". He demonstrates a typical way to pass the results of a particle effect on to the compositing team for further refinement. This courseware will give you a clear idea of what is required of a VFX professional and how excellent results are achieved under the pressure of a real deadline.

This video introduces viewers to the powerful world of VOPs within Houdini, and how it can be used to direct particles via it's point cloud features. Exploring VOPs implementations in shading & rendering, geometry and POPs it presents an entire workflow that brings them together to provide you with an intuitive way to control particles. Central to this cg-ku.com workflow is the process of developing a "point cloud advect" Digital Asset that can be re-used in any particle system- allowing the user to push particles around with arbitrary geometry that could come from SOPs, another sim or even a Mantra render.