halo patrick baudisch, microsoft research, LDUX* & ruth rosenholtz, parc, ASD april 10 th, CHI 2003 *while at xerox parc, now parc inc.

+ the problem

halo

contents halo is not a focus plus context technique (related work) halo is a lamp shining onto the street (designing halo) halo is 16-33% faster than arrow-based visualization techniques (user study) build interactive halo applications! (conclusions, lessons learned)

related work driving directions vs. route planning aids overview-plus-detail focus-plus-context pointing into off-screen space

halo design

cinematography 1.entry and exit points 2.point of view arrow-based techniques 3.partially out of the frame halo rings are familiar, graceful degradation

streetlamps aura visible from distance aura is round overlapping auras aggregate fading of aura indicates distance what we changed smooth transition sharp edge disks rings dark background light background

intrusion border handle space for arcs… and for corner arcs reserve space for content

arc length = distance

handling many objects find best (restaurant): relevance cut-off see all (dangers): merge arcs

app designers can use color texture arc thickness

user study

interfaces arc/arrow fading off scale m/cm map as backdrop readability ok same selectable size hypothesis: halo faster halo ring distance from display border legend

pre-study to define tasks 8 participants (6 GPS users, 2 PDA users) informal interviews minutes 4 tasks to be used in study

1. locate task click at expected location of off-screen targets had to simulate on PC

2. closest task click arrow/arc or off-screen location closest to car

3. traverse task click all five targets so as to form shortest path

4. avoid task click on hospital farthest away from traffic jams

procedure 12 participants within subject design, counterbalanced four training maps per interface/task, then eight timed maps questionnaire

task completion time TaskArrow interfaceHalo interface Locate20.1 (7.3)16.8 (6.7) Closest9.9 (10.1)6.6 (5.3) Traverse20.6 (14.1)16.8 (8.7) Avoid9.2 (4.7)7.7 (5.8) 33% 16%

error rate TaskArrow interfaceHalo interface Locate23.5 pixels (21.6)28.4 pixels (33.8) Closest22% (42%)21% (41%) Traverse97.4 pixels (94.7)81.0 pixels (96.7) Avoid15% (35%)14% (34%) participants underestimated distances by 26% participants saw ovals (gestalt laws?) we can compensate for that: width += 35%

subjective preference

conclusions halo 16%-33% faster than arrows –no split attention –distortion-free space –scale independent –no need to annotate distance –perceive all rings at once [treisman & gormican] limitation: max number or rings future work: applications where peripheral objects move and change

Thanks! try halo: polle zellweger, jock mackinlay, lance good, and mark stefik ( citylights short paper talk) scott minneman and allison woodruff

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Extra

(a) locate(b) closest (d) avoid(c) traverse