Head-Tracked Head-Tracked Displays (HTDs)Displays (HTDs)

Sherman and Craig, pp. 140-Sherman and Craig, pp. 140-151151

Head-tracked DisplaysHead-tracked Displays

Displays in which the user’s head is Displays in which the user’s head is tracked and the image display tracked and the image display screen is located at a fixed location screen is located at a fixed location in physical space.in physical space.

Examples?Examples? CRTCRT Virtual Workbench or ImmersaDeskVirtual Workbench or ImmersaDesk CAVECAVE Many large screen displaysMany large screen displays

CRT HTD (Fishtank VR)CRT HTD (Fishtank VR)

3D Glasses

Head Tracker

Stationary Display

Stereoscopic DisplayStereoscopic Display

User

C

AB

Screen

C

A

B

Standard Display Stereoscopic Display

Virtual WorkbenchVirtual Workbench3D Glasses

3D Display

3D Object

CAVECAVE

Any Projected Large Stereoscopic Any Projected Large Stereoscopic ScreenScreen

CharacteristicsCharacteristics

LargeLarge Projection-Based (except for Projection-Based (except for

Fishtank VR)Fishtank VR) StereoscopicStereoscopic Head TrackedHead Tracked Stationary Display Screen(s)Stationary Display Screen(s) Let’s try to identify the pros and Let’s try to identify the pros and

cons and application domainscons and application domains

3D Glasses

3D Display

3D Object

Large Screen ProjectionLarge Screen Projection

Larger field-of-Larger field-of-view than HMDview than HMD

Field of regard is Field of regard is smaller than HMD smaller than HMD but larger than a but larger than a typical CRT typical CRT DisplayDisplay

Projectors must be Projectors must be aligned properly.aligned properly.

Architectural Architectural Statement!Statement! Front Projection (user Front Projection (user

may be in the way).may be in the way). Back Projection (takes Back Projection (takes

up even more space)up even more space) When multiple When multiple

screens are arranged screens are arranged at or near 90 degree at or near 90 degree angles, reflection angles, reflection between screens may between screens may be a problembe a problem

Large Screen ProjectionLarge Screen Projection

AdvantagesAdvantages Viewer not isolated from Viewer not isolated from

real objects or other real objects or other people in the virtual people in the virtual world space.world space.

Less physical gear to Less physical gear to wear than HMDwear than HMD

Potentially better Potentially better resolution than HMDresolution than HMD

Large field of view Large field of view compared to HMD or compared to HMD or CRT.CRT.

DisadvantageDisadvantagess Usually one one person Usually one one person

is head-tracked.is head-tracked. Real objects may occlude Real objects may occlude

virtual objects in virtual objects in inappropriate waysinappropriate ways

Multiple screens require Multiple screens require more computationmore computation

At least one direction is At least one direction is not part of the virtual not part of the virtual world.world.

LightingLighting