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'The Magic of Houdini': Introduction and Welcome

VFXWorld begins its new excerpt series from Will Cunninghams book, The Magic of Houdini.

All images from The Magic of Houdini by Will Cunningham. Reprinted with permission.

This is the first of a new series of excerpts from the Thomson Course Technology book The Magic of Houdini by Will Cunningham. In the next few months VFXWorld readers will learn the basics of the dominant tool that has been used in the creation of some of the most awe-inspiring animation and cinematic effects ever made.

Why This Book Was Written

Because it was sorely needed! This project swirled and coalesced from the origins of several years spent teaching and never having exactly the material I wanted to use for instruction. It grew from meager, isolated exercises into a cohesive, comprehensive whole that should serve well in getting essential information to a beginner and also giving more knowledgeable users a resource for studying areas new to them. Houdini is a vast package of immense capabilities. Hopefully, this book will help you through some areas you have yet to explore and give additional insight in areas you are already familiar with.

Basically, this book is the compilation of almost everything I wish I had when I was trying to scale the peaks of a package with a steep learning curve and few resources to get you going. In addition, it takes a few steps beyond that and introduces topics like VOPs and DOPs, which are areas where even the most seasoned professionals can often use more practice. They may sound strange, but VOPs and DOPs are just acronyms for various contexts within Houdini. VOPs means VEX Operators and DOPs means Dynamics Operators. As you progress through the book, you will get familiar with these and a number of other contexts.

History of Computer Animation at a Blink

Somewhere and some time in the volumetrically foggy past, you must have been dazzled by the artistry of this medium. Most everyone in this industry can trace his or her enthusiasm back to some seminal moment in days gone by where the magic of the movie moment was enthralling and lasting. The past few decades have introduced and cemented the use of computer graphics across the visual medium. What was once limited to research and graduate projects has spread to become fully integrated in the fields of television, research visualization, art, print media, video games, the Internet and, of course, feature films. Movies like Tron (1982) and The Last Starfighter (1984) were among the first to beautifully integrate computer animation with live-action on the big screen.

As the technology progressed, more and more films began to incorporate the new medium in order to enrich an environment, create an entirely imaginary one, add effects that were too costly, dangerous, or impractical to perform in real life and more. Then The Abyss (1989) entered the stage and indelibly made 3D animation a part of the production process. The stunning effects achieved by Industrial Light & Magic in this film brought those beautiful pseudopods and for the first time showed that a totally fabricated 3D character could evoke and embody emotion. Since that time, we have been the fortunate viewers to a maturing process that continues to hold me in thrall.

History of Houdini at a Glance

Having been a Houdini intern in days gone by for Side Effects, Ive met most of the folks who work there and they are all very cordial and civilized. I nevertheless continue to believe that all the programmers, at least, live in a dark cave somewhere outside of Toronto and do nothing but work to improve the software. During the various company gatherings and my chances to meet the Canadian contingent of employees, I was continually impressed that the long years of isolated living in near lightless conditions hadnt made any of them socially inept or unduly increased the size of their eyes and pupils.

It is rare to encounter a company that is among the top competitors in its field and yet also maintains a very friendly and informal air. This attitude prevails throughout the Houdini community as well and is part of what makes it such a great package to use.

PRISMS and then Houdini have been used in some of the most innovative films ever created, including What Dreams May Come, The Matrix, Titanic, The Chronicles of Narnia: The Lion, The Witch and The Wardrobe and more. It is a good bet that if you go to the theatre and see something that blows your mind, Houdini had a hand in it. In 1998 Side Effects received a technical achievement award from The Academy of Motion Pictures, Arts and Sciences for the procedural modeling and animation components of PRISMS, (which were passed along and continue to be refined in Houdini). In 2002, the Apprentice edition was released and so finally the masses had legal access to the software for learning and tinkering. This free learning version has almost all the functionality of the complete Master version and so is a great way to learn the package and you dont have to worry about the FBI coming to your house inquiring about what youve downloaded recently! In 2003, The Academy of Motion Pictures, Arts and Sciences awarded numerous folk at Side Effects the Academy plaque in honor of their contribution to the movie making process. In 2005, Side Effects finally incorporated an integrated Rigid Body Dynamics and Soft Body Dynamics context in the package, much to the profound happiness of its users!

Check out for more information about Houdinis history and its innovations in the industry. As they say, its always good to know your roots.

[Figure 1] A spherical field of stars.

Houdinis Procedural Paradigm

As I have now mentioned proceduralism several times, its a good time to explain it in detail. Its one of the fundamental features and advantages of the Houdini package.

One of the defining aspects of the Houdini workflow centers on its procedural paradigm. Well, that certainly sounds impressive; but, what does it actually mean and why is it beneficial? Simply put, Houdini is designed so that every operation is a self-contained black box (or node) of utility. The term black box is used to describe a situation in which you dont necessarily need to know exactly how something is happening inside the box so long as you understand what is happening to its inputs and outputs. For example, I might not really know how a Copy PolyBevel operation does what it does, but I do know that if I feed star geometry into one input and sphere geometry into the other input, it ends up doing something very useful. Figure 1shows the result of this simple network. Figure 2 shows the network of nodes used to create the field of stars. In the example, the flow of information is from top to bottom and the lines between the nodes indicate the connection between nodes, and so how the data is flowing. So, data from the circle node to the group_points_to_pull node to the xform_make_star node and finally into the left input of the copy_data_to_sphere node. The sphere_template node feeds data into the right input of the copy_data_to_sphere node. Basically, the star geometry feeds into the left input of the final node and the sphere geometry feeds into the right input of the final node.

[Figure 2] The network of nodes used to create the field of stars.

Each of these nodes takes one or more inputs, acts upon them in some way, and then passes the result as the final output or to the next node in the line. Inherently, this approach lends itself to the creative approach of problem-solving because the user has the freedom to add, delete, or modify an operation at any stage in the process in order to see how it affects the end result. Replacing the star geometry with a teapot, the network automatically updates itself and you get the image in Figure 3. Figure 4 shows the modified network of nodes used to create the new image.

Webster defines procedure as a series of steps followed in a regular definite order. This is partly reflective of Houdinis usage of procedural in that projects, grand and small, are all built upon a series of steps as described. However, the Webster lexicon is partly not reflective of the Houdini usage in that the user is not restricted to a regular definite order. One of the great liberties of this package is that there are many paths available to reach a single objective. It is simply up to the experience, ability and artistry of the user to determine which path is the most efficient, extensible and aesthetically pleasing for the project at hand.

[Figure 3] A spherical field of teapots.

My Perspective

Alas, you encounter the unabashed opinions of the author! Over the past several years, I have studied a number of 3D packages and found them all to be reasonably capable; however, in Houdini, I found creative freedom. Strap on your tissue holsters, I am talking feelings here. From the beginning and continuing to this day, I have always felt that Houdini offers the tools to fit my mindset and creative approach instead of forcing my approach into the confines of the tools.

I am also fascinated with the way in which Houdini seems to stimulate both the creative and analytical aspects of my mind. The art at the beginning of this chapter juxtaposes these two approaches with the torii gate being a stylized and creative symbol interacting with the mechanical and interlocking gears. When in harmony, these two aspects of the mind and approaches can produce powerful and pleasing results. You can easily see an example of this in the interface when comparing the Viewer pane (as shown in Figures 1 and 3) and the Network Editor pane (as shown in Figures 2 and 4). Each pane essentially represents the same information. However, the Viewer expresses this in a way that appeals to the visual, spatial, creative right brain, whereas the Network Editor shows causal relationships, orders of flow and details that appeal to the analytical left brain.

[Figure 4] The network of nodes used to create the field of teapots.

This sort of symbiotic relationship pervades the program and provides continuous opportunities to focus the whole of the brain on the task at hand.

Initially, I looked upon the vast and darkened landscape of this packages methodology with excitement and more than a little trepidation. As we all know, out under the moon surrounded by dimmed sky, the strangest things can and likely will happen. Today, I can still see quite a number of unexplored peaks in the distance. And I happily look forward to encountering each of them knowing that a solid grasp on the basics will capably take me into whatever adventures lay ahead. I hope you can find the same enjoyment on your own quest in this ever-expanding electronic multiverse.

So, please proceed with eager intention and bold demeanor! Yeehaa!

Find out more about how to apply each of Houdinis features to your projects as you take on modeling, character animation, particle effects animation, dynamic simulation animation, shading, digital asset creation and rendering. The Magic of Houdini by Will Cunninham. Boston, MA: Thomson Course Technology, 2006. 355 pages with illustrations. ISBN: 1-59863-082-2 ($49.95). Check back to VFXWorld frequently to read new excerpts.

Will Cunningham began his trek by studying both traditional art subjects and 3D computer software at the Academy of Entertainment and Technology. After his studies, he was hired as a Houdini technical intern by Side Effects, the developers of the Houdini software package. Eager to create effects for the big screen, he then jumped into production with BlackBox Digital on the feature, The Prince and Me. Shortly thereafter, he also began teaching Introduction to Houdini at the Academy and has since taught both the introductory and intermediate Houdini courses. In the fall of 2004, he was awarded a fellowship grant by Santa Monica College to support his efforts in creating this book. Over the years, Will has worked for a number of production studios on a variety of projects, including The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, Open Season and Ghost Rider. Currently, he is enjoying effects challenges and learning opportunities at Sony Pictures Imageworks.