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Upcoming Deadlines. Art/Physics 123 Furlough Day: Monday, September 14th Fourth Homework (Tracker video analysis of Falling): Due Wednesday, September 16 th ; 15 points (10 points if late) Fifth Homework (Video analysis of Path of Action): Due Wednesday, September 23 rd ; - PowerPoint PPT Presentation

Transcript of Upcoming Deadlines

  • Upcoming DeadlinesArt/Physics 123 Furlough Day:Monday, September 14th

    Fourth Homework (Tracker video analysis of Falling):Due Wednesday, September 16th ; 15 points (10 points if late)

    Fifth Homework (Video analysis of Path of Action):Due Wednesday, September 23rd ; 15 points (10 points if late)

    For full schedule, visit course website:ArtPhysics123.pbworks.com

  • Homework Assignment #4We will be using a video analysis program called "Tracker" to study motion. Download a copy of the program from the Tracker website: http://www.cabrillo.edu/~dbrown/tracker/

    Run the Tracker program on your computer, import the video clip of a falling object that you created in the previous homework assignment and analyze the falling motion (will demo in class today). This assignment is due by 8am on Wednesday, September 16th (next week).

  • Guest LectureNext Wednesdays class will be a special guest lecture by Rex Grignon. Rex has been the Head of Character Animation on numerous films, starting with Antz (1998), Shrek (2001), Madagascar 2005) and Madagascar: Escape 2 Africa (2008) and has animated on Sinbad (2000) and Kung Fu Panda (2008).Note: Need volunteer assistant

  • Extra Credit OpportunityExhibition runs through Jan. 10.Give me your ticket receipt for ten points extra credit.Hours: Tuesday Sunday, 11am - 5pm Admission: $4.00 for studentsLocation: 655 Mission Street San Francisco, California 94105Near Moscone Convention CenterVisit the Cartoon Art Museum in San Francisco to see Once Upon a Dream: The Art of Sleeping Beauty.

  • Activating your Clicker* Turn on your clicker.* Enter the number or letter that I give you for joining this class. Hit Enter/Send key.* Clicker should read PHY123SCI2* Type in your student ID; hit Enter/Send.Clicker is now ready to use.Hit any key to wake the clicker from sleep mode.

  • Video Reference

  • Analyzing Video ReferenceOne of the most useful tools for an animator is a movie camera for shooting reference.

    Reference is not for rotoscoping (tracing images from a film) but to study the motion.We can also use video analysis tools to help us see the patterns of motion in a scene that weve filmed.

  • Tracker Video Analysis SoftwareLet me demonstrate how to use the Tracker software for video analysis software.To download Tracker, visit: http://www.cabrillo.edu/~dbrown/tracker/Tracker is a free program created by Doug Brown, a physicist at Cabrillo College.

  • Tracking the Ball DropHorizontal MotionVertical Motion

  • Importing Video into TrackerRun the Tracker program on your computer and import your video clip of a falling object.You may need to convert your clip into a format that Tracker can import (either MOV or AVI), if it's not already in that format. If you have trouble using your clip from Homework 3 then you may shoot new reference.

  • Tracking an Object in TrackerIn the "Tracks" menu select "New -> Point Mass"; a Track Control window should appear.

    Press the second button in the Track Control window and select the "Full Trails" option.Go to the first frame in your clip that you want to analyze, hold down the shift key to change the cursor into cross-hairs, then click on the center of your object. The program will mark that position and advance one frame.

  • Tracking an Object (cont.)Continue holding down the shift and marking the position of the object until it hits the ground (which should be after 15 to 20 frames). Due to motion blur the object will "stretch" as it falls and it may be difficult to locate the exact center but just do your best to estimate the center of the blur.

  • Plotting the Position DataClick on the "Plots" button in the upper-right corner and select the 2 plot option.

    You now have two plots showing the horizontal (x) and vertical (y) positions of the object versus time. Select and drag the bar separating the plots from the data tables and pull the bar down to expand the plots window.

  • Posting your PlotsIn the "Edit" menu select "Copy Image -> Frame" to copy the whole window to the clipboard.

    Open your favorite graphics program, such as Paint or PhotoShop, paste the image, then save it to a file. Finally, upload that image to your blog into a post called "Tracker video analysis of falling".

  • Graph of Ball Drop HeightsFramesHeightNotice the shape of the curve made by the dots. This is a parabolic arc.

  • Motion GraphsIn computer animation the timing and spacing of motion is often viewed using motion graphs, which can be manipulated in a graph editor..PositionFrame

  • Autodesk Maya softwareMaya is one of the leading tools in computer animation.

  • Motion Graphs in MayaThe motion graph for a ball drop looks something like this in MayaPositionFrame

  • Maya Demo for Bouncing BallLet me demonstrate how to set up a simple bouncing ball in Autodesk Maya.Our animation will be of a ball that is 4 inches in diameter (2 inches in radius)

    The ball will fall from a height of 4 feet (48 inches).

    It takes second (12 frames) to reach the ground.Use Fourth Down at Half Time

  • Using Reference WiselyArtists know that reference is very important but they also recognize that they shouldnt be slaves to their reference.Thomas Eakins,The Swimming Hole (c. 1884)Photo reference shot by Eakins

  • Using Physics WiselyPhysics helps understand motion yet animators shouldnt be slaves to it either.

  • Speed and AccelerationSpeed (or velocity) is defined as how quickly an objects position is changing.

    Acceleration is defined as how quickly an objects velocity is changing.

    Tracker calculates speed and acceleration from the position data for an object.

  • Graph of Spacings (by Odd Rule)FramesSpacing1357911By the Odd Rule, the spacings go as 1, 3, 5, 7, 9, etc.The graph of speed is also a straight line.

  • Falling SpeedWith this table you can find the speed of an object from the distance its fallen.

    However, this table is accurate only as long as the objects weight is much larger than the force of air resistance.

    Distance fallen from apexSpeed (inches per frame)Speed(miles per hour)1 foot454 feet8109 feet121516 feet162025 feet202536 feet243049 feet2835100 feet4050400 feet80100

  • Falling Speed ExampleAbout how fast is Alice falling? She is 4 feet tall. We are shooting on twos (2 frames per drawing).5 m.p.h.15m.p.h.25m.p.h.35 m.p.h.50 m.p.h.

    Distance fallen from apexSpeed (inches per frame)Speed(miles per hour)1 foot454 feet8109 feet121516 feet162025 feet202536 feet243049 feet2835100 feet4050400 feet80100

  • Falling Speed ExampleDistance between keys is about two feet; shot on twos thats 12 inches per frame.

    Either shes only fallen from just off-screen (above) or her dress is slowing her fall.About how fast is Alice falling? She is 4 feet tall. We are shooting on twos (2 frames per drawing).

    Distance fallen from apexSpeed (inches per frame)Speed(miles per hour)1 foot454 feet8109 feet121516 feet162025 feet202536 feet243049 feet2835100 feet4050400 feet80100

  • Increments & AccelerationIn the Odd Rule, the spacings get bigger with time and always by the same amount.

    That is, the increment from one spacing to the next is always the same (red arrow).

    Since the spacings tell you the speed, if the spacings get larger and larger then the moving object is accelerating.

    The increment tells you the acceleration. The acceleration due to gravity is constant (since the increment is always the same).

  • Differential CalculusYou now know basic differential calculus.

    The difference between the positions of the ball is the spacing, which gives the speed.The difference between the spacings is the increment, which gives the acceleration.

  • Next MondayNo Class (Course Furlough)

    Next WednesdayGuest Lecture: Rex Grignon

    By Wednesday of next week:Complete the 4th homework(Tracker video analysis of Falling)Please return the clickers!

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