oCharacteristics of AR systems oApplications oTypes of AR oIssues in AR Human Factors 2: Augmented Reality

Augmented Reality Characteristics oCombines real and virtual: virtual objects superimposed or composited with the real world (adding and/or removing) oInteractive in real time oRegistered in 3-D oIn contrast to VE’s, AR supplements reality rather than replacing it

Components of an AR system NB: AR can be applied to all senses. There are systems that are being developed that can accommodate sound, in which the user wears headphones equipped with microphones.

Why use AR? oThe information conveyed by the virtual objects helps the user perform real-world tasks. It provides information to the user that is not directly available to the user’s senses otherwise.

Applications oMedical: project non-invasive imaging scans (MRI, CT, ultrasound) onto the patient’s body - “x-ray vision”. Particularly useful for minimally invasive surgery. Also for guiding precision surgery or training. ultrasound guided needle biopsy

Applications oAssembly, maintenance and repair: Instructions available on-site as superimposed 3D drawings (video)

Applications oVisualization: e.g. architects may visualize how a particular structure will change the view of the environment. Or they may employ “x-ray vision” to visualize pipes, electric lines or structural supports inside walls (video). oAnnotation: tag objects or enviroments with public or private information. E.g. a context sensitive (hand- held) display could provide info on library books as the user walks around a library.

object ID object ID NaviCam [Rekimoto, UIST’94] context-sensitive information assistant

Applications oRobot path planning: due to long communication delays with a real robot, controlling the virtual version may be preferable oMilitary aircraft: superimpose vector graphics onto the pilot’s view of the world oEntertainment: e.g. virtual sets merging real actors with virtual backgrounds

Applications oWearable computing: context-sensitive & mobile

Types oOptical see-through HMD oVideo see-through HMD oMonitor based AR

Optical See-Through HMD

Video See-Through HMD

Monitor based AR

Issues in AR What’s wrong with this picture?

Issues in AR oWIMP interface is fundamentally wrong for AR oUsers are very sensitive to visual offsets (<1 min of arc) - HMD trackers and displays cannot provide this level of accuracy: the registration problem (not so much a problem in VE’s). Note that some applications will demand high accuracy! oStatic errors: optical distortion; errors in tracking; misalignments oDynamic errors: end-to-end system latency (pot. solutions: lag reduction; temporal stream matching (only w. video based systems); location prediction) oAR is in its infancy: No turnkey, off-the-shelf AR systems available; much research still needed on perceptual, cognitive and social issues