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

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... 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


1
VR UI, Notes on Projects,Intro. to Object
Descriptions
  • Glenn G. ChappellCHAPPELLG_at_member.ams.org
  • U. of Alaska Fairbanks
  • CS 481/681 Lecture Notes
  • Wednesday, February 25, 2004

2
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
    reference
  • glPushMatrix()
  • glTransform(myUser.getTransf(USR_WAND))
  • // Draw transformed objects
  • glPopMatrix()

3
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
    up/down)?
  • Solution 1
  • wandDir1 0.
  • wandDir wandDir.normalized()
  • Solution 2
  • wandDir - wandDir.component(vec(0.,1.,0.))
  • wandDir wandDir.normalized()

4
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
    want
  • Picking, keyboard, menu
  • All of these are trickier in VR.

5
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.

6
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?

7
VR User InterfaceObject Manipulation 1/2
  • When we manipulate objects, we deal with the
    following
  • 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

8
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?

9
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.

10
Notes on ProjectsOverview
  • 100 points of your grade in this class will be a
    project.
  • 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
    extensive.
  • Plan to do a short in-class presentation as well.

11
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.

12
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.

13
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
    surfaces.
  • Splines Generating useful explicit descriptions
    based on control points.
  • Implicit surfaces and their applications.
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