Business and Computing Deanery

Multimedia

Week 19 Animation, camerasand video

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Last week Lecture Planning your model Boolean 2D to 3D Polygon modelling

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This week Animation Cameras Video

Streaming Compression Production

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Concepts What is animation? Modification of any

kind of object Light Material Camera

What can you change? Parameters

Position Rotation Scale

What parameters have been changed?

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Frames A series of still

images Frames

Persistence of vision Illusion of fluid

motion

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Frame rates Frame rate

Speed at which the images are displayed

Frames per second Different systems

have different rates Standard rate in UK

for output to film is 24fps

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Timeline controls VCR like section of the interface

9 Animation playback controls10 Animation keying controls14 Track bar15 Time slider

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Key framing Like traditional 2D

animation techniques

Specific frames Tweening

Computer calculates the parameters of the object’s position for each intermediate frame

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Time controls Start or end Default scene starts with 100

If the output is set to 24 fps how long will this last?

Can be changed with the Time Configuration button

Auto Key Move to a frame, transform objects or

change their parameters. All changes register as keyframes.

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Activity Open up your model of a room Save with a different name Add something and make it move

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Constraints Animation constraints are used to help

automate the animation process. Used to control an object’s

Position Rotation scale

A binding relationship with another object Requires one object and at least one

target object The target imposes specific limits on the

constrained object

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Motion paths A path constraint

restricts an object's movement along a spline

The spline curve (target) defines a path of motion for the constrained object.

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Pivot points and axes An Orientation

constraint causes an object’s orientation to follow the orientation of an object

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Cameras Virtual cameras duplicate the

functions and controls of real-world cameras

What controls does a real-world camera have?

A. Focal lengthB. Field of View

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Focal length The distance between the lens and

the light-sensitive surface Lens size

28mm wide angled lens 50mm normal lens 85mm long focus and more….

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Field of view Field of View

the width of your view as an angle with its apex at your viewpoint and the ends at the sides of the view

Relates to the lens size 28mm wide angled lens

75o

50mm normal lens 40o

85mm long focus 24o

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Creating cameras Target Free

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Free v. target A Free camera has a single icon to

animate The Target camera has two

the target the camera

You can switch between camera types, changing a Free camera to a Target and back again

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Camera view Make the viewport

active then press C key The Viewport

navigation controls change

Different controls for cameras than for the Perspective viewport Dolly, pan, orbit

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Activity Add a camera to your scene and

view it through the viewport

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Moving cameras 1 Pan

Rotates the target about the camera

Tilt or orbit Rotates a camera

about the target

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Moving cameras 2 Dolly

Moves the camera and/or its target along the camera's main axis

Truck Moves the camera

parallel to the view plane

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Animating a camera Following a moving object Moving a camera along a track Panning Orbiting Zooming

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Following a moving object The Look-At constraint makes the

object replace the camera’s target or

Link a target camera’s target to the object

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Zooming Zooming moves toward or away

from the camera’s subject matter by changing the focal length of the lens

It differs from dollying, which physically moves the camera but leaves the focal length unchanged

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Activity Animate the camera view

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Discussion How can you add a video to a

multimedia production?

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Types rendering Renders viewport view Quick render Render to file

Still image, frame Animation

Render to print Quicktime VR

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File types The rendered output can be a still image

or an animation A selection of file types

AVI File (AVI) BMP Image file (BMP) Encapsulated PostScript format (EPS, PS) JPEG File (JPG) MOV QuickTime file (MOV) PNG Image File (PNG) TIF Image File (TIF)

Which are used for still or animation?

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Render output - avi Compressor

Set the codec (compressor/decompressor)

Compression Quality The higher you set the quality,

the larger the file size will be. Lossy technique

Keyframe Rate Specify the interval between

the delta keyframes used to compare one frame with another and generate in-between frames. 3ds max v7

Why compress? NTSC

uncompressed 640x480 pixels per

frame x 3 bytes per pixel

(24 bit colour) x 30 frames per

second (approx) ≈ 26 MB per

second ≈ 1.6 GB per

minute

PAL uncompressed 768x576 pixels per

frame x 3 bytes per pixel

(24 bit colour) x 25 frames per

second ≈ 31 MB per

second ≈ 1.85 GB per

minute

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Chapman N and Chapman J (2004).

Play back a video stream as it arrives over a network (like broadcast TV), instead of downloading an entire video clip and playing it from disk (like renting a DVD)

Streamed Video197

Chapman N and Chapman J (2004).

HTTP StreamingStart playing a downloaded clip as soon as enough of it has arrivedStarts when the (estimated) time to download the rest is equal to the duration of the clip

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Chapman N and Chapman J (2004).

Video Compression Spatial (intra-frame) compression

Compress each frame in isolation, treating it as a bitmapped image

Temporal (inter-frame) compression Compress sequences of frames by only

storing differences between them Always some compression because

of sub-sampling

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Spatial Compression Image compression applied to each frame Can therefore be lossless or lossy, but

lossless rarely produces sufficiently high compression ratios for volume of data

Lossless compression implies a loss of quality if decompressed then recompressed

Ideally, work with uncompressed video during post-production

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Temporal Compression Key frames are spatially compressed

only Key frames often regularly spaced (e.g.

every 12 frames) Difference frames only store the

differences between the frame and the preceding frame or most recent key frame

Difference frames can be efficiently spatially compressed

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Vector Quantization Divide each frame into small

rectangular blocks (’vectors’) Code Book – collection of constant

vectors representing typical patterns (edges, textures, flat colour,…)

Compress by replacing each vector in image by index of vector from code book that most closely resembles it

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Codecs Cinepak – Longest established, high

compression ratio, takes much longer to compress than to decompress

Intel Indeo – Similar to Cinepak, but roughly 30% faster compression

Sorenson – More recent, higher quality and better compression ratios than other two All three based on vector quantization Quality of all three inferior to MPEG-4

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MPEG-4 Standard defines an encoding for

multimedia streams made up of different sorts of object – video, still images, animation, 3-D models…

Higher profiles divide a scene into arbitrarily shaped video objects each one may be compressed and transmitted separately, scene is composed at the receiving end by combining them

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Post-Production Changing or adding to the material

Most changes are generalizations of image manipulation operations (e.g. colour correction, blurring and sharpening,…)

Compositing – combining elements from different shots into a composite sequence

Animating elements and combining animation with live action

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Preparing for Delivery Compromises required to bring

resource requirements of video within capabilities of delivery media (e.g. networks) and low-end machines Reduce frame size (e.g. downsample to

quarter frame) Reduce frame rate (12fps is OK for

smooth motion, flicker not a problem on computer)

Reduce colour depth

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Render settings in Max Resolution

Height and width in pixels

Consider aspect ratio Colour depth

8 bit allows 256 colours 24 bit allows 16 million More colours helps

reduce banding and errors

Anti-aliasing Active time segment Alpha channel

Atmospherics Eg. fog

Effects Eg. Blur

Advanced lighting Use a radiosity solution

or light tracing in the rendering

Render output

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Activity – output as a video Create an animation and output as an AVI Set the following

Active time segment 320 x 240 Files > Save as AVI Give it a name and note where you are saving

it Click Setup

Use Sorenson compression 15 fps 50% compression

Click Render

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Self assessment You have been asked to model a

lecture theatre for Hope and produce an animated video showing the lecture theatre Describe, compare and contrast 3

camera animations Describe the process of output of the

video with justification for choices of settings

Describe the purpose of video CODECS, how they work

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For Next Week Work on Portfolio 2.2 Work on the 3ds max tutorials Directed reading

(DM) Chapter 9 (GA) Chapter 9

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References Giambruno M, (2002) 3D Graphics & Animation,

2nd Edition, New Riders, ISBN: 0-7357-1243-3 Kerlow I. V., (2003) The Art of 3-D Computer

Animation and Effects , 3rd Edition, John Wiley & Sons Inc; ISBN: 0471430366

Murdock K.L., (2005) 3DS Max 7 Bible, John Wiley & Sons Inc, ISBN: 0764579711

Screen shots taken from 3ds max 7 User Reference