Space perception
Download
1 / 61

Space Perception - PowerPoint PPT Presentation


  • 117 Views
  • Uploaded on
  • Presentation posted in: General

Space Perception. Depth Cues Tasks Shape-from-Shading. Perception of surface shape. Simple lighting model Light from above and at infinity Specular, Diffuse and Ambient components Oriented texture can enhance shape perception. Lighting model. Lambertian, specular, ambient + cast shadows.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

Space Perception

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Space perception
Space Perception

  • Depth Cues

  • Tasks

  • Shape-from-Shading


Perception of surface shape
Perception of surface shape

  • Simple lighting model

  • Light from above and at infinity

  • Specular, Diffuse and Ambient components

  • Oriented texture can enhance shape perception


Lighting model
Lighting model

Lambertian, specular, ambient + cast shadows


Standard lighting model
Standard lighting model

Ambient illumination

Specular refection

diffuse reflection =

lambertian



Shading
Shading

Specular reveals fine detail





Lighting
Lighting

  • Simple lighting model

  • Not photorealistic

  • Single light source from above and at infinity

  • Specular for detail

  • Cast shadows if scene is simple


The 3d vs 2d debate
The 3D vs 2D debate

  • Should we display abstract data in 3D?

  • Depth cue theory

  • Depth cues are environmental information that tell us about space

  • Can be applied somewhat independently





Perspective cockburn and mckenzie
Perspective (Cockburn andMcKenzie)

Perspective

Picture plane position

Occlusion

Picture plane position

Occlusion


Atmospheric perspective
Atmospheric perspective

Reduce contrast with distance

“depth cueing” in CG





Stereopsis
Stereopsis

  • Based on disparities

  • A super acuity

  • Only good near point of fixation

  • Poor for large differences

  • Double imaging possible for 1/10th deg.



Relative importance
Relative Importance

, 96

Motion

parallax

0.001

Occlusion

Height in field

0.01

Relative size

Depth Contrast

0.1

Binocular

disparity

Convergence

accommodation

1.0

Aerial

1

10

100

Depth (meters)

Cutting, 1996



3d options
3D options

Vergence

Focus

Motion

Parallax

Stereopsis

Shape-from

Shading or

Texture

Perspective

Occlusion



Yes of course 3d can give us more but only if it supports some task
Yes of course 3D can give us moreBut only if it supports some task

  • Locomotion

    • Heading, occlusion

  • Understanding the shape of surfaces

    • Shading, texture, stereo, motion

  • Tracing paths in graphs

    • motion stereo

  • Local reaching

    • stereo – convergence


Relative position
Relative position

  • For fine judgments - threading a needle stereo is important +shadows, occlusion

  • For large scale judgments, perspective, motion parallax, linear perspective are all important. Stereo is not important






Space perception

Stereo +60%

Motion +130%

Stereo + Motion

+200%


How to generate motion
How to generateMotion?

  • Passive rotation

  • Hand coupled rotation

  • Head-coupled rotation

  • Time has does not vary much


Stereo display requirements
Stereo Display Requirements

  • 3D GIS data

  • Comfortable stereo display

  • Many orders of magnitude

  • Better than normal stereopsis



We know that
We Know That

  • Vergence and focus conflict

  • Stereo perception is plastic (Wallack)

  • Can be rapidly recalibrated (Judge and Miles)

  • There is a synergy with motion parallax

  • Occlusion is a strong cue to depth



Cyclopean scale helps with
Cyclopean Scale Helps with

  • Vergence focus conflict

  • Diplopia

  • Disparity scaling

  • Frame cancellation

  • It works dynamically?

  • Change the virtual eye separation




Understanding surface shape
Understanding surface shape

Victoria Interrante


Norman todd phillips
Norman, Todd & Phillips

Note: Random textures on surfaces

Stereo and motion roughly equal

Note large angular error ~ 20 degrees

Observation: Stereopsis is a super-acuity and relies on fine texture disparity gradients


Conclusion 3d is better but only it adds something

Space perception depends on the task

Occlusion the most important depth cue – consider that windows rely on it

Perspective may not add anything by itself

Stereo important for close interaction

Motion important for 3D layout

Shape-from shading and texture important for surface perception (but non photorealist)

Conclusion – 3D is better but only it adds something


Stereo technologies
Stereo technologies

  • Frame-sequential (shutter glasses)

  • Polaroids

  • Mirror stereoscope

  • HMDs

  • Color anaglyphs

  • Chromadepth

  • Holograms


Stereo shutter glasses
Stereo shutter glasses

Alternate right and left eye images on monitor. Syncronized shutters block right and left eyes in alternation

Monitor: 120 Hz

R,L eyes 60 Hz each

Problems: ghosting due to slow

Phosphor decay.

Lower resolution

CRT displays only

Expensive glasses


Polaroids
Polaroids

Silver screen

Preserves polarization

R

L

Problems:

ghosting

Advantages: Cheap glasses


Anaglyphs
Anaglyphs

Problems:

Ghosting

Inability to use color


Lenticular

Works with LCD displays

Lenticular

To Right Eye

To Left Eye

The display uses cylindrical

Prisms in vertical columns

What is wrong with this picture?

Problems: reduced resolution, limited head position.

Theoretical limits on resolution


Mirror stereoscope
Mirror stereoscope

Advantages: no ghosting

Retains full brightness

Full spatiotemporal resolution possible

Disadvantage: Fixed head position.


Hmd stereoscope
HMD stereoscope

Different screens for each eye.

A high image quality is possible, but not currently available


Space perception
VR

  • What is it?

  • What is it for?

  • Perception/interaction


Issue
Issue

  • Resolution

  • Ghosting

  • Vergence-focus conflict

  • Occlusion

  • Crossed disparities


Immersion vr
Immersion VR

  • HMD + head tracking

  • Data glove


Fish tank vr1
Fish Tank VR

  • Head tracking, stereo, touch


Desk top vr
Desk Top VR

  • Interactive 3D


Space perception
CAVE

  • Head tracking – stereo

  • Resolution problems

  • Light scattering problems

  • Vergence focus problem for near object

  • Occlusion problems for near objects


Data walls near immersion
Data walls (near immersion)

  • Stereo, no head tracking, wide screen


Immersadesk
Immersadesk

  • Head tracking, stereo


Augmented reality feiner
Augmented reality (Feiner)

  • Add text+images to real world

  • See through glasses

  • Very sensitive to head tracking

  • Occlusion problems


ad
  • Login