Class Notes
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Who am I
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Nice guy
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Qualified (run web site with 3500 people/week and 117,000 hits/day 200,000
people so far)
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How class is run
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Some lecture, mostly hands on
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Interrupt as you will
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Can eat food
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Will have a break
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Be nice to hardware
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Standard day will be I talk for 20 minutes, you work for an hour, break,
repeat, quit
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What will we learn
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How browsers interperate images
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Built-in types vs. plugins
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What the image types are
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Size, quality, etc
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How to make images
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VRML
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How browsers deal with images
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Built-in means that Netscape knows how to handle it
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JPG
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Lossy but can vary quality as needed
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Small and fast
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Horrible for repeated edits because of repeated losses
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GIF
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Lossless
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Bigger and slower
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Does great for line drawings but still very good for pictures
![](D-21_launch.gif) |
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Original GIF |
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50% Quality JPG |
10% Quality JPG |
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Plug-in means that netscape only knows the 'type' of the image, and the
program to run to display it.
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Can be any type, including types not thought of by Netscape Inc.
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"Display" can mean anything, including play the sound or release the smell.
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VRML and all the cool multimedia types are all plugins.
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What is VRML
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Pronouced "vermal"
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Means "Virtual Reality Modeling Language"
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Is a way of describing
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3d objects with textures, colors, and anchors (links)
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viewpoints
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lights
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motion
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VRML is an industry standard, so lots of viewers can show it.
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How to make VRML?
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Use a text editor, write vrml
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Maximally powerful, but very slow and painful for the writer
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Use a VRML based 3d graphics editor
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Easy to use, but can be imprecise with positioning
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Only allows features built into the editor
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Use a different editor like AutoCAD, and convert
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Generally loose features not built into the other editor, like links
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VRML Basics
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The world has three axis
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X means left and right
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Y means up and down
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Z means toward you and away from you
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If you turn, the axis don't move, but the meaning change (think about it)
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VRML worlds consist of objects and nothing but objects
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Objects have a type (box, cylinder, cone, light, viewpoint, group, etc)
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Objects have a scale (how big it is)
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Objects have a translation (where is the object)
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Objects have a rotation (which direction does it point)
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Objects have a surface (color, texture, transparency, etc)