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Peter Plantec

- About the Book

VIRTUAL HUMANS: A Build-It-Yourself Kit
by Peter Plantec

"Virtual Humans" may seem like something out of science fiction, but they are already here. Companies use them as website hosts, individuals use them as personal assistants, and people interact with them in computer games, educational applications, and many other arenas. The possibilities are limitless, but the most amazing thing is that anyone can create a "V-human" from scratch. Virtual Humans gives not just start-to-finish instructions for designing a charming synthetic person, but also a CD-ROM containing the tools and techniques to make it real. Readers will learn how to:

  • create their own authentic and engaging personalities
  • apply VH technology to business and individual projects
  • add synthetic voices and realistic faces to virtual humans
  • use personality psychology and humor in character design
  • design advanced emotion expression engines

This book-and-CD package is the first of its kind and a landmark on a par with the first build-your-own-Web-site products. Readers will be among the first to create ultra- realistic, versatile V-human personalities, and will start well ahead of what is soon to be a tidal wave of worldwide interest.


Copyright (c)2004 by Peter Plantec. All rights reserved. Printed here with permission of the publisher, AMACOM, http://www.amanet.org/books.


- Excerpt


A Build-It-Yourself Kit

by Peter Plantec


The excerpt, below, is taken from the path breaking new book by Peter Plantec, Virtual Humans. Just as digital video put filmmaking into the hands of ordinary people, so Virtual Humans puts computer animation into the hands of the home hobbyist and small business.

Virtual Humans is a build-it-yourself kit for creating web-based virtual assistants. This is not pie-in-the-sky A.I. It's not about *making* smart machines -- it's about *faking* smart machines. Plantec shows you how to create the *illusion* of conscious intelligence through careful Q&A scripting and sophisticated facial expressions. The result is a bot that can guide visitors through your web site, answering simple questions and collecting information.

The excerpt discusses the two most important tools for creating the illusion of intelligence: scripting and facial expression. It includes a humorous scripting failure and a two-scale method for morphing facial expressions. More information about the book, Virtual Humans, and author Peter Plantec follows the excerpt. Have fun!

Scripting and Expressions for Virtual Humans

by Peter Plantec


Many individuals and companies are working on ways to generate face and body expressions and track them with emotional context. My approach yields subtle and nonrepeated facial expressions linked to emotionally correct verbal responses. You won't find my engine on the CD-ROM that comes with the book, but with this information you can ponder and play with your own rules when building your own virtual human using the tools on the CD. Mine is but one approach, which I offer to get you thinking about how you'd like to handle emotion. If you're a true hacker you might like to build an engine like this and post it at my web site, http://www.v-people.com, for others to experiment with.

I use two linked affect engines to create a flow of mood, attitude, and emotion. (The word "affect" here means emotional context. The root word is affection -- as in "The child shows flat affect" -- meaning he's not displaying any emotion.) One engine registers and expresses general mood, while the other, more fine-tuned engine, measures and expresses instant situational emotional peaks. Mood is a quality that varies slowly over time. It's based on a stream of values from a numeric Happy-Sad scale, averaged over time.

For example, if someone is verbally abusive to our V- person, Dawn, she can express concern, yet let it roll off her back if she's in a positive mood. If maltreatment continues for a while, it's going to get her down, as negative scores accumulate over time. Conversely, a really nice person might bring her out of a bad mood and have her be all smiles. Plus (+) values indicate varying levels of happiness, while minus (-) values indicate sadness. I use an arbitrary range of minus to plus 10. Some user inputs will have a zero or neutral effect on mood. No single input will have a large or immediate impact on mood because the input values are averaged over time.

Situational affect is emotional expression tied to a specific input stream, and is immediately expressed. It doesn't happen all the time, but if the V-person is insulted, they need to know it and express shock, disappointment and/or anger, while giving the user a cutting verbal slice. Such responses strongly suggest humanness, and they encourage the suspension of disbelief. Done properly, the instant affect engine detects direct insults, then instructs both the display (face) engine and the natural language engine how to deal with it.

Earlier in the book, I indicated that your menu of responses for any given rule can have several random choices that can be displayed. But now instead of being randomly selected, you can use the output from mood and instant affect engines to select special responses when necessary. The choice depends on mood or instant affect, whichever is greater. You can set a threshold for instant affect to kick in. I'd say any input or question that rates over +/- 6 on any one scale should trigger a response geared to that emotion. For example, if you get: "I really hate the way you look," it will trigger the gestalt pattern: "I*you*look*," which has response alternates including:

"Thank you very much."
"I really appreciate that."
"Oh gosh, I'm embarrassed."
"Are you trying to upset me?"
"You really need to get some glasses."
"Oh, thanks."

Because the word "hate" has a high anger value of -9 for Dawn, the instant engine automatically triggers the response designed for high negative affect: "Are you trying to upset me?" while sending a surprised/distressed expression to the 3D real-time face display.

Meanwhile, Dawn's mood determines her baseline responses to less emotionally-charged inputs. For example, if she's in a good mood any of the first three responses might be selected at random. If her mood level drops below an arbitrary threshold that you set, she'll say: "Oh, thanks," with a slightly depressed look on her face (the unfelt smile), indicating that she's not buying this. In fact, as Dawn's mood declines, her overall facial expression takes on subtle signs of distress or depression, as shown in Figure 1. This is accomplished by blending-in increasing percentages of different facial expressions, known as "morph targets." More on morph targets later in the book.

In Figure 2, you can see another example of facial expressions associated with mood. Conrad's expressions, as shown here, are entirely the result of morph blending. You'll be able to do your own experiments with morph blending using BioVirtual's 3dMeNow Demo included on the CD-ROM.

In yet another example, Dawn's feeling fine and responds to "How are you feeling today?" with "I'm well, and you?" -- said with a happy face. But when she's below mood threshold, she'll respond with, "I've been better, why do you want to know?" -- said with a slightly depressed face. In this example I use the A-C (Angry-Calm) scale to determine immediate affect. But with a little programming skill you can build an engine that will track several different scales. The use of multiple emotional scales is discussed later in the book.


Scripting is the creation of gestalt rules. Be aware that I'm probably the only person on earth who calls them "gestalt rules." Being a psychologist, I like to think in psychological terms. When your V-person gets the gist of a conversation, and responds well, people will start to attribute all sorts of wisdom to her or him. You'll find that most people have no idea what's possible in virtual humans, and they'll tend to see much more than is actually there. It's the art of illusion.

Sylvie: "Hi, I'm Sylvie. What's your name."    Female Guest: "I'm Diane."    Sylvie: "Hello, Diane. It's nice to meet you."    Diane: "What do you think of these parties?"    Sylvie: "I like parties. (pause) Lots of people to play  with."    Diane: "That was a good answer."    Sylvie: "Thank you."    Diane: "How smart are you, Sylvie?"    Sylvie: "I'm not smart enough, but I try to give the  illusion that I'm brilliant. (smile)"    Diane: "Well, you have me fooled."    Sylvie: "Is that a good thing?"    Diane: "I don't know."    Sylvie: "Me either."          

Sylvie was equipped with a set of rules I'd built up over about a year with help from others. She comes off as quite intelligent and even charming. Fortunately, Diane's questions matched well with the rules at hand. She took questions from several people and left most of them feeling that she is much smarter than she actually is. More than smart, she left people with the impression that she has "being." One woman in public relations said that she had chills after her visit with Sylvie.

I have to tell my favorite Sylvie story. Once while demonstrating her to the press at a meeting near Boston, a woman reporter asked her if she knew any children's stories. Normally she does, but in my great wisdom, I'd removed them and added stuff I thought reporters would be more interested in. To cover the empty space and I put in a few rules that struck me very late at night. By morning I'd forgotten them.

Reporter: "Do you know any children's stories?"    Sylvie: "Yes, I know a really cool children's story."    The reporter than asked her to tell the story, but Sylvie  couldn't find it.    Sylvie: "I can't find the damn kid's story. Peetie, are you  here?"    Me: "Yes, Sylvie, I'm here."    Sylvie (with an angry look): "Where the hell did you put  the damn kid's story, I can't find it in here."    Me: "It's my fault, Sylvie, I took it out."    Sylvie: "This is embarrassing, Peter. You are such a  naughty boy."          

I never suspected this scripting would ever see the light of day. If I did, the words would have been more politically correct. But I'm glad she came out with it because the reporters were rolling on the floor. It was a thousand times better than if she'd actually recited her little story. An embarrassing moment won the day.

The artistry of personality design is something you can learn. Sometimes your best stuff will come late at night or after a few beers. It's always best when you loosen up. You know it's going well when you're having fun. I taught a young sports writer from The Washington Post the basics of how to script one evening. He immediately got into the personality of one female character. Late that night, I noticed he was still scripting her. The results were wonderful.

For some it will be easier than for others, but with an understanding of human personality -- that word again -- and a sense of humor, you'll be able to create a believable personality.

Now that you have an idea of what a good brain engine must do to fake consciousness, and you've given up all hope for sapience, you're ready for some actual scripting experience. Let's move on to the next chapter where we'll meet Mr. Lincoln.

Copyright (c)2004 by Peter Plantec. All rights reserved. Printed here with permission of the publisher, AMACOM, http://www.amanet.org/books.

About the Author

Peter Plantec (Aspen, Colorado) is the creator of Sylvie, the first commercially available virtual human interface, and cofounder of Virtual Personalities, Inc. A psychologist, animator, and software designer, he heads both OrdinaryMagic.com and V-people.com. He is contributing editor and columnist at AV Video/Multimedia Producer Magazine, and is the author of Caligari trueSpace 2 Bible, a number one best-seller in its genre.

Copyright (c)2004 by Peter Plantec. All rights reserved. Printed here with permission of the publisher, AMACOM, http://www.amanet.org/books.

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