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VR UI, Notes on Projects, Intro' to Object Descriptions


... terms of transformations, one of the trickier parts of VR is moving objects ... All of these are trickier in VR. 25 Feb 2004. CS 481/681. 5. VR User ... – PowerPoint PPT presentation

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Title: VR UI, Notes on Projects, Intro' to Object Descriptions

VR UI, Notes on Projects,Intro. to Object
  • Glenn G. ChappellCHAPPELLG_at_member.ams.org
  • U. of Alaska Fairbanks
  • CS 481/681 Lecture Notes
  • Wednesday, February 25, 2004

ReviewVR TRANSF 1/2
  • In terms of transformations, one of the trickier
    parts of VR is moving objects together in an
    arbitrary frame of reference.
  • For example, moving an object with the wand.
  • To draw an object in the wands frame of
  • glPushMatrix()
  • glTransform(myUser.getTransf(USR_WAND))
  • // Draw transformed objects
  • glPopMatrix()

ReviewVR TRANSF 2/2
  • To find where the wand points
  • vec wandDir myUser.getFrontVec(USR_WAND)
  • How do we turn this into a 2-D vector (no
  • Solution 1
  • wandDir1 0.
  • wandDir wandDir.normalized()
  • Solution 2
  • wandDir - wandDir.component(vec(0.,1.,0.))
  • wandDir wandDir.normalized()

VR User InterfaceThree Hard Problems
  • In CS 381, we discussed view the world and
    move in the world interfaces. We also discussed
    picking, keyboard-handling, and menus.
  • There are three problems here
  • How to Navigate
  • Move in the World
  • Flying, driving, etc.
  • How to Manipulate Objects.
  • View the World
  • Picking
  • How to Initiate Actions
  • In other words, how to tell the computer what you
  • Picking, keyboard, menu
  • All of these are trickier in VR.

VR User InterfaceNavigation 1/2
  • In VR we are generally either moving around on a
    floor/ground surface, or in the air/space.
  • In the latter case, we can have a uniform up
    direction or not.
  • Or we may not be able to move at all.
  • This gives four general types of navigation
  • None
  • Like most desktop programs objects move, but the
    user is stationary.
  • Sort of
  • Walking/Driving
  • We still might allow stairs, bridges, elevators
  • Airplane-style Flying
  • Up is always up.
  • Spaceship-style Flying
  • Anything goes.

VR User InterfaceNavigation 2/2
  • Four Types of Navigation
  • None
  • Walking/Driving
  • Airplane-style Flying
  • Spaceship-style Flying
  • What would be a useful UI for each of these?

VR User InterfaceObject Manipulation 1/2
  • When we manipulate objects, we deal with the
  • Can we pick up an object?
  • If so, how do we determine which one?
  • How do we drop it?
  • What does it do while it is grabbed?
  • Can we move an object without picking it up?
  • How?
  • Can we perform actions with/on an object without
    moving it?
  • What things?
  • Similar questions to those above

VR User InterfaceObject Manipulation 2/2
  • Other Problems
  • How to deal with clutter?
  • How to limit the number of actions we can perform
    so that users dont have to learn remember a
    lot, and internal object interfaces are simpler?
  • How can we write object interfaces so that all
    objects can coexist in a friendly way?

VR User InterfaceInitiating Actions
  • More generally, we have the problem of how to
    tell the computer what to do.
  • Remember, we are in a VR environment. Users
    already know how to deal with reality (we hope).
    How can we make use of this knowledge?
  • Users have 3-D input devices. So, for example,
    treating the wand like a 2-D mouse is silly.
  • There is no keyboard.
  • Menus are a pain, as usual.

Notes on ProjectsOverview
  • 100 points of your grade in this class will be a
  • Projects will be graded via a contract system
  • Each student individually negotiates project
    requirements with me.
  • If all requirements are met, then you get 100.
  • Proposed requirements are due, as part of
    Assignment 5, in a couple of weeks.
  • Your grade on Assignment 5 has nothing to do with
    your grade on the project.
  • General requirements
  • Projects will be due on Thursday, April 22.
  • It is generally expected that you will turn in a
    preliminary version two weeks before that
    (Thursday, April 8).
  • In your project proposal, specify what the
    preliminary version will include.
  • If, for some reason, you think you need to handle
    the preliminary version differently, put this in
    your proposal.
  • Some documentation is required. It need not be
  • Plan to do a short in-class presentation as well.

Notes on ProjectsWhat to Do?
  • For project length and difficulty, think in terms
    of four regular assignments.
  • Possible topics
  • Implement, and use in a program, some
    (relatively) advanced CG method.
  • Ray tracing?
  • Try out some new user-interface idea.
  • A navigation method in VR, etc.
  • Two words VR game (okay, thats three words).
  • 3-D fractals, chaos, or whatever.
  • Something else
  • Use of VR Juggler the Discovery Lab is
    encouraged, but not required.

Intro. to Object DescriptionsOverview 1/2
  • Descriptions of surfaces (and thus of 3-D
    objects) can be roughly split into three types
  • Polygon List
  • A list of the polygons (and/or polylines, points)
    that make up a surface.
  • Example triangle (0, 0, 0), (0.5, 0, 0), (1,
    1.2, 0) triangle (1, 1.2, 0), (0.5, 0, 0), (2,
    1, 1).
  • Explicit Description
  • Surface is described explicitly, using formulae.
  • We call this a parametric surface.
  • Example (s, t, t2), for 0 ? s ? 1 and 0 ? t ? 1.
  • Implicit Description
  • Surface is described implicitly, using equations.
  • Example x3 3xyz3 4z2sin y 8.

Intro. to Object DescriptionsOverview 2/2
  • Again
  • Polygon List
  • Explicit Description
  • Implicit Description
  • So far, we have dealt only with polygon lists.
  • Now, we look at
  • Pros Cons of the above three.
  • Using formulae to describe curves and curved
  • Splines Generating useful explicit descriptions
    based on control points.
  • Implicit surfaces and their applications.
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