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Project Summary

Difficulty	8
Time required	Average (about one week)
Prerequisites	None
Material Availability	To do this science fair project, you will need to download and install a free program, called Scratch. See the Experimental Procedure for more details.
Cost	Very Low (under $20)
Safety	No issues

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Abstract

Objective

The goal of this science fair project is to evaluate how changing the timing between three different animation poses affects how you perceive the quality of a video game character's punch.

Introduction

When a character does something on screen, the game makers want you, the player, to register some kind of opinion about the action—even if it's a subconscious opinion. For example, a character who is running away from a monster should look like he or she is running fast, a dancer leaping in the air should look graceful, and a fighter delivering a knock-out blow should look like he or she has a strong, powerful punch. But using animation to convey the feel of an action might be more difficult than you think.

An animation is made up of several different poses. These poses are still pictures of a character at a given moment. When the poses are displayed on screen quickly, one after another, it appears as though the character is moving. You may already be familiar with this concept if you've ever made a flip book, or even thumbed through the pages in a comic book quickly. Changing the length of time for which each pose is displayed on the screen affects the viewer's perception of the action. For example, if you make a flip book of a girl walking and you thumb through it slowly, it'll appear as though she's strolling, but if you flip through the same book very quickly, the girl will appear to run. In this example, a shorter display time per pose makes the action appear to happen more rapidly.

In video games, the length of time for which a pose is displayed is measured in frames. Each game has a frame rate. The frame rate is the number of times per second that the image on the screen is refreshed, or updated. Frame rates vary from game to game, but two of the most common frame rates are 30 frames per second and 60 frames per second. For this science fair project, you'll use a 60-frames-per-second rate, so each frame will be equivalent to one-sixtieth of 1 second.

In this science fair project, you'll examine how the number of frames each pose in a punch animation is displayed for affects your perception of the punch. First, think about how many poses there are in a punch. Try getting up and moving around the room throwing pretend punches (and no, you can't practice on your sibling!). What is the minimum number of motions you think can be used to convey the action of a punch? To complete this science fair project, you'll use a program that has a punch animation sequence composed of four poses. Figure 1, below, shows images of the individual poses. The first is an idle pose where the fighter is in a position suggesting that he is ready to fight, but his fists are still low down. The second is a windup pose, where the fighter draws his arm back to get ready to throw the punch. The third is a hit pose, where the fighter's arm is fully extended, as if his fist has made contact with the target. And the fourth pose is the finish pose, where the fighter's fists are back close to his body, but still high up, relative to his shoulders, as if he has just finished retracting his arm after the punch. You'll systematically change the frame count (number of frames for which a pose is displayed on the screen) for the windup, hit, and finish poses and evaluate how that affects how powerful the punch appears.

Figure 1. In this science fair project you'll use sprites of the character Ryu from Street Fighter Alpha 3 to evaluate how frame count for individual poses in a punch animation sequence affects perceived power of the punch. You'll use four different poses: an idle, a windup, a hit, and a finish pose.

Terms, Concepts and Questions to Start Background Research

• Animation
• Pose
• Flip book
• Frame rate
• Refresh
• Sprite
• Scratch^TM program
• Subjective
• Qualitative
• Quantitative
• Standard deviation

Questions

• Why is frame rate important for video games?
• How do frame rates in video games, movies, and television compare?
• What is the difference between a game's frame rate, and the frame count for individual poses within an animation sequence in the game? How does the game's frame rate affect the minimum frame count for a pose?
• What are ways to turn a qualitative measurement into a quantitative measurement?
• How do you calculate standard deviation and what does it tell you about the amount of variability in a data set?

Bibliography

These resources will give you more background information about frame rate:

• Wikipedia Contributors. (2009, February 19). Frame rate. Wikipedia: The Free Encyclopedia. Retrieved February 19, 2009, from http://en.wikipedia.org/w/index.php?title=Frame_rate&oldid=271736811
• deHaan, J. and Georgenes, C. (2009). Flash Animation Learning Guide. Retrieved February 19, 2009, from http://www.adobe.com/devnet/flash/articles/animation_guide_02.html

For more information about standard deviation, try these resources:

• Green, L. (2001, February, 26). Mean, Mode, Median, and Standard Deviation. Retrieved February 19, 2009, from http://www.ltcconline.net/greenl/courses/201/descstat/mean.htm
• Stanbrough, JL. (2004, May 23). Standard Deviation. Retrieved February 19, 2009, from http://www.batesville.k12.in.us/Physics/APPhyNet/Measurement/standard_deviation.htm
• Statistics Canada. (2008, December 11). Variance and Standard Deviation. Retrieved February 19, 2009, from http://www.statcan.gc.ca/edu/power-pouvoir/ch12/5214891-eng.htm

These resources will introduce you to Scratch:

• Scratch Team, MIT. (n.d.). Scratch. Retrieved February 18, 2009, from http://scratch.mit.edu/
• Scratch Team, MIT. (n.d.). Scratch version 1.3 Reference Guide. Retrieved February 18, 2009, from http://info.scratch.mit.edu/Support
• LearnScratch.org. 2008. Learn Scratch. Retrieved February 18, 2009, from http://learnscratch.org/index.php
• Ford Jr., Jerry Lee. Scratch Programming for Teens. Boston: Course Technology, 2009.

Materials and Equipment

• Computer with Scratch installed, see Experimental Procedure for details on installing Scratch for free.
• Spreadsheet program, like Microsoft® Excel®
• Lab notebook
• Optional: Scratch Programming for Teens by Jerry Lee Ford, Jr. available from www.amazon.com

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Experimental Procedure

• For this science fair project, you'll use Scratch, a programming interface developed by researchers at the Massachusetts Institute of Technology (MIT), to look at and manipulate a punch animation sequence.
• This science fair project does not require you to do any programming. But you may find yourself interested in experimenting with Scratch, or trying one of the suggestions listed in the Variations section, which does require programming. If so, here are some resources you can use to help you with your programming:
  • Try consulting the various "how-to" guides and references on the Scratch Support page.
  • The http://learnscratch.org/ website also has a large number of free video tutorials on how to program with Scratch.
  • Jerry Lee Ford, Jr.'s book Scratch Programming for Teens (listed in the Materials and Equipment section, above) is also a good resource for learning more about programming, in general, and how to use Scratch, in specific.
  • Sometimes looking at other people's code is a good way to learn how to program something. The Scratch download comes with several projects already completed, and all the scripts for each one are available for you to look at.
  • Other programmers can also be a great resource. Try asking friends or family members, who have experience programming, for tips and advice, or log on to the Scratch Forums and post a question.
    • Important Note: Your personal data is extremely valuable, particularly on the Internet, and can be used against you if someone else gets a hold of it. Keep it protected. Never give your real name, address, phone number, the name of your school, or a picture of yourself to anyone online. Email addresses, user account names, and screen names should not be your real name, the name of your school, or some combination of the two. For more Internet Safety tips, visit the Science Buddies Internet Safety Guide.

Installing and Getting Started with Scratch

1. To start this science fair project, you should go to the Scratch download page at http://scratch.mit.edu/download and follow the instructions there to download and install Scratch for free.
2. Once Scratch is installed, click here to download the file you'll need to complete this project.
   1. Save the file with the name Games_p024_PowerPlay.sb.
   2. When you are ready to start your project, use Scratch to open the file.
3. Once the Games_p024_PowerPlay.sb file is open, click the "Enter Presentation Mode" button in Scratch. In Presentation Mode, the character will be larger and the action will be easier to see and evaluate.
   1. The "Enter Presentation Mode" button is located in the left-hand corner, directly underneath the white screen where the sprite is displayed.
4. To get a general idea of how the fighter's punch looks, play around with the number of frames (in this case, each frame is one-sixtieth of a second) for which each pose is held.
   1. Press the spacebar to watch the fighter throw his punch.
   2. The length of time for which each pose is held is controlled by a slider on the screen. See Figure 2, below. Experiment with moving each slider to 0, 30, or 60 frames. This is the equivalent of not seeing the pose at all, seeing it for half a second, or seeing it for a full second.
   3. Evaluate whether the punches look good or bad. Are they jerky or smooth, real or fake, weak or powerful? Note all observations in your lab notebook.

Figure 2. In Presentation Mode in Scratch, you can adjust the frame count for each pose using the sliders, and then view the resulting punch by pressing the space bar.

Collecting the Data

Now that you have a general idea about the range of how good or bad a punch can look, depending on the timing of the animation poses, you're ready to collect your detailed data.

1. Put the frame counts for each pose at these starting settings:
   1. Windup Frame Count = 24
   2. Hit Frame Count = 12
   3. Finish Frame Count = 8
2. Hit the spacebar to view the punch. You'll need to decide how "good" the punch is. Since judging an animation's quality is subjective and qualitative, you'll break up the evaluation into three different 1–10 rating scales to make the assessment more precise and quantitative.
   1. First evaluate the smoothness of the animation on a scale of 1–10, where 1 is very jerky and 10 is very smooth.
   2. Next, evaluate how real the animation looks. Is it the kind of punch you'd expect a professional boxer to throw during a boxing match? Use a 1–10 scale, where 1 is very fake and 10 is very real.
      • If you aren't familiar with boxing, and need some examples of what a fake punch might look like, try these settings for the windup, hit, and finish frames:
        • No windup, goes straight into the punch: 0, 12, 8
        • Punching arm hangs out in the air too long: 24, 40, 8
   3. Lastly, evaluate how powerful the punch appears using a 1–10 scale, where 1 is a punch that looks very lightweight and weak, whereas 10 is a punch that looks very heavy, powerful, and damaging.
   4. Note: You may need to view the punch several times to make your evaluations.
   5. Calculate the overall quality score for the punch by adding together the scores from each of the three rating scales.
      • The worst punch possible would have a quality score of 3.
      • The best punch possible would have a quality score of 30.
   6. In the spreadsheet program, make a data table to keep track of the frame counts for each pose, the score you give the punch on each of the three rating scales, and the overall punch quality score.
3. Examine how the number of frames for which the windup pose is played affects the quality of the punch.
   1. Increase the windup frame count by 2 and re-evaluate the quality of the punch using the method outlined in step 2. Remember to record your data in the spreadsheet.
   2. Continue to systematically increase the windup frame count by 2 and re-evaluate the punch quality until the frame count is at 60.
   3. Reset the windup frame count to 2 less than its starting value (in the case of the windup pose, the starting value is 24 so it should be reset to 22 frames). Repeat the same quality assessment procedure outlined in step 2.
   4. Continue to systematically decrease the windup frame count by 2 and re-evaluate the quality of the punch until the frame count is at 0.
   5. Note: Do not change the frame counts for either the hit pose or the finish pose during these evaluations.
4. Reset all of the pose frame counts to their starting positions listed in step 1.
5. Using the same method outlined above for the windup pose, examine how the number of frames the hit and finish poses are played for affects the quality of the punch. In the end, you should have three sets of data:
   1. One where the windup frame count varies from 0 to 60, while the hit and finish frames remain at 12 and 8, respectively.
   2. A second data set where the hit frame count varies from 0 to 60, while the windup and finish frames remain at 24 and 8, respectively. Start with the hit frame count at 12 and evaluate for higher (up to 60) and then lower than 12 (down to 0) frame counts.
   3. A third data set where the finish frame count varies from 0 to 60, while the windup and hit frames remain at 24 and 12, respectively. Start with the finish frame count at 8 and evaluate for higher (up to 60), and then lower than 8 (down to 0) frame counts.
6. On two additional days, repeat steps 1–5 so that you have three trials for each data set. By doing each trial on a separate day, you're more likely to have the data capture the range of your true impressions of each punch.

Analyzing the Data

1. For each of the data sets, calculate the average punch quality score across the three trials, and the standard deviation. The standard deviation is a statistic describing how much variation there is among the different trials; the greater the standard deviation, the larger the differences between the trials. Most spreadsheets, like Microsoft Excel, have a function to calculate standard deviation. Consult the help menu of your spreadsheet program and the references in the Bibliography for more information about standard deviation and how to calculate it.
2. Make an XY graph for each of the data sets. The frame count for the pose being evaluated should be on the x-axis. The quality scores should be on the y-axis.
   1. On each graph, plot the average quality scores and the standard deviation for those scores.
3. Use your graphs to answer these questions:
   1. From one trial to the next, was there a lot of variability between your perception of what the punch quality score should be? Was the variability uniform across the three poses? Was the variability uniform across the range of frame counts or did it increase or decrease dramatically at different points?
   2. Are the shapes of the graphs similar or different? What does this tell you about the importance of each pose in the total quality score? Does one pose appear to be more important than the others or are they all equal?
   3. Looking at your graphs, can you pick out what the best frame count for each pose is? Is there a single value or a range for each pose?
   4. Using your data, what are the frame count settings for the best overall punch you can make using the poses you were given?

Variations

• Judging how good an animation looks is subjective, but just how much variability is there between individuals? Try the experiment above with several of your friends. Is there more variability within a single person's punch quality ratings or between the ratings of several people?
• How many poses are necessary to portray different actions? Try using Scratch to put together different animation sequences, like running, jumping, throwing a ball, performing a ballet twirl, etc. You can download sprites from the Internet, use your own drawings, or even use photographs of you and your friends in the various poses. What is the minimum number of poses needed to convey the action? Do more poses make the action look better?

• For more science project ideas in this area of science, see Video & Computer Games Project Ideas.

Credits

Ian Slutz, Video Game Designer

Sandra Slutz PhD, Science Buddies

• Scratch^TM is a trademark of the Massachusetts Institute of Technology.
• Microsoft® is a registered trademark of Microsoft Corporation.
• Excel® is a registered trademark of Microsoft Corporation.

Last edit date: 2009-03-27 11:38:00

Career Focus

If you like this project, you might enjoy exploring careers in Video & Computer Games.

Multimedia Artist or Animator If you've ever watched a cartoon, played a video game, or seen an animated movie, you've seen the work of multimedia artists and animators. People in these careers use computers to create the series of pictures that form the animated images or special effects seen in movies, television programs, and computer games.

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