Perception of Objects in TechnicalIllustrations - A Challenge in Technical

Communication

Debopriyo RoyAssociate ProfessorUniversity of Aizu

December 12, 2010

Presentation at IEEE PCS-J, Nagano City, Japan

Depth Perception Depth perception is the visual ability to perceive the world

in three dimensions (3D)and the distance of an object.

Monocular cues provide depth information when viewing ascene with one eye.

We perceive depth with 2 main sources of information: A. Binocular disparity B. Monocular cues

Depth Perceptions & Technical Illustrations

How should technicalillustrators demonstratephysical orientation tounderstand procedures

What should be thecharacteristics of thedisplay plane forvisualizing procedures?

Specific Issues for Technical Writers

How do we design body/object positions inuser manuals most effectively for secondlanguage speakers such that a minimalist textapproach is viable.

Would readers in EFL context understand thesubtle difference within body and objectpositions /orientations, based on difference intasks when explained with minimal English text?

Affordance - 1 (Image Plane)Anatomical Image Plane -

Axial - Image slices that areperpendicular to the long axis ofthe body

Coronal-Image slices that bisects thefront and back sides of the body

Sagittal- Image slices that bisects theleft and right side of the body

Affordance -2 (Optimal Perspective)

Canonical View - Front, side and top views of an object.

Affordance - 3 (Task-based)Orientation of Illustrations

Weight of the ball

Pressure on the knees

Pressure on the shoulder

Grip to lift the ball

Leg fold

Ankle pressure

Transfer of weight

Bend of vertebral column

Characteristics of DisplayPlanes

Distance between legs

Exact location of the ball

Angle of shoulder bend

Angle between hips and legs

Head Position

Extent of Knee folds

Direction of ball lift

Displacement during lift

Overall Camera angle

Visual Systems People use at least two visual systems when performing tasks in

the three dimensional world.

One system involves primary processing of visual information bythe back of the brain with subsequent processing by its sides.

Side areas seem to specialize in object identification (e.g., cube vs.cylinder).

The other system performs secondary visual processing at the top-rear of the brain and helps with body orientation in space.

Object Manipulation vs. Physical Orientation Research findings suggest

that people use different partsof their brains when doingtasks requiring objectmanipulation.

However, the extent of suchuse diminishes when doingtasks requiring physicalorientation of their bodiesin three-dimensional space.

Ball Grip

BallRelease

Two Dimensional Views of ThreeDimensional Plane For on-screen or print

materials, people onlyhave monocular cues tohelp them interpret whatthey see.

This reduction of depthcues makesinterpretation moredifficult and anillustration’s point of viewmore critical.

Object vs. Body-Centered View

Research has shown thatthe effects of mentalrotation depend on pointof view.

Spectator’s point of view

Performer’s point of view

Perception of Distances

People are better at judgingdistances directly across thedisplay plane.

In Figure 1, the height of thebox relative to the man’s waistis clearly visible. This isbecause the distance is acrossthe display plane.

However, the distancebetween the box and theman’s chest is not visiblebecause the movement is intothe display plane.

Perception of More Complex PhysicalPostures

In this figure, thedistance between anytwo object is recognizedmostly as a function ofother body posturesand parts.

To understand thisobject, different angularverification along eachof X, Y and Z axis isrequired.

Illustrations and Instructions Heiser and Tversky found (for a

furniture assembly task) thatillustrations showing objectspartially rotated is easier tounderstand than objects showedhead on.

Szlichcinski found illustrationsshowing slightly rotated objects tohave more task-based affordance.

He also found that hand positions inillustrations are duplicated in actualtasks exactly as shown.

Image Perceptions

Force up / down Push / Pull Angular Push / Pull Pressure up/down Showing direction Showing shape Grip Throw Turn Squeeze Twist Entire Body Posture

Variations of Viewpoints - Body PosturesHeight /Angle of Camera Const. -AlongWaistline

No manipulation Z & Y axis manipulation Z, Y, X axis manipulation

X & Z axis manipulation Z, X & Y axis manipulation X, Z and Y axis manipulation

Variations of Viewpoints - Camera Rotationalong waist line (X & Z axis manipulation)

2/3rd Front 1/3rd Side Side 1/3rd Back

Back 1/3rd Back 2/3rd Front

Variations of Viewpoints - Z axismanipulation

Movement along Y axis

Movement along Z axis

Object / Posture / Visual Angle Complexity

Bend angle Bend angle, ankle movement Hand pressure, grip

Exact box position, leg pressure, grip,leg rotation, twist, finger folds to holdthe box

Hypotheses Major Research Question -

Previous studies do notresolve conflict betweenorientation of illustrationsversus characteristics ofdisplay plane.

Illustrations that show aperformer’s point of view will beeasier to use.

Illustrations that place importantdistances across the displayplane will be easier to use.

Methods - 1

Test subjects were asked to evaluate body images via amatching task.

20 subjects were tested and each subject rated 20 sets ofimages.

Poser Figure Artist software used to design body positionsand angles. It sustains accurate three dimensionalrelationship among body parts.

Variations of viewpoints and body positions were tested.

Methods - 2 (Operation Matrix)

Task # 1: Man with the box

Methods - 3 (Operationalization of Trials)

Summary of Findings

Subjects were most confident for images shown directly fromfront or back.

Somewhat less confident of the images rotated one-thirdfrom the front or back. (contrary to literature)

Least confident of images shown from side. Two views did poorly - images rotated 1/3rd from front and

back. (contrary to literature) Average number of correct choices were around 45%. Average correct matches for direct head-on view, 1/3rd back

and back views cluster around 40-50%. 1/3rd front and side views vary tremendously.

Ongoing Analysis on Performance:Accuracy Scores

Correlation between accuracy rates for different heightsof the box along the Y axis.

Correlation between accuracy rates for thedisplacement types. (Extensive further analysis requiredfor Z-axis manipulations into the display plane).

5 different coordinates were chosen for trial: (2, 6, 0); (3 ,6, 2); (4, 6, 4); (4, 6, 6); (3, 6, 5)

Correlation between camera angle rotations along thewaist / chest.

Future Analysis Variation in displacement types on the basis of action:1. Carrying 2. Lifting 3. Pulling 4. Pushing

Differentiate between postures on the basis of props.1. Chair 2. Ball 3. Box 4. Handle 5. Sphere/Triangle. - Purpose is to determine whether object shape is a function of

performance and accuracy with physical tasks.OS = f[A f1(D, CA)]

Variation in displacement types based on movement:E.g., left, center and right oriented displacement variations.E.g., variation along the Y axis.E.g., variation into display plane (z axis).

Free Viewpoint - Looking into Future Free viewpoint television (FTV) is a system for viewing natural

video, allowing the user to interactively control the viewpoint andgenerate new views of a dynamic scene from any 3D position.

With FTV, the focus of attention can be controlled by the viewersrather than a director, meaning that each viewer may beobserving a unique viewpoint.

This technology might revolutionize the way we look atinteractive procedural user manuals. Readers will be able toswitch views as and when they need to, based on task.

However, this might not necessarily improve proceduralaccuracy, because of uncontrolled access to viewpoints,enabling spatial misconception.

Japan’s Promise for WC Football 2022 Japanese organizers

say each game will befilmed by 200 highdefinition cameras,which will use"freeviewpoint"technology to allowfans to see the actionunfold from a player'seye view -- the kind ofimages until now onlyseen in video games.

(CNN.com - 1st Dec,2010)

THANK YOU !