This document discusses challenges in conveying depth perception and physical orientation through technical illustrations. It reports that: 1) Readers best understood illustrations shown directly from the front or back, and least understood side views or those rotated partially from front/back. 2) On average, readers correctly matched body positions in illustrations only 45% of the time. Views involving distances into the display plane were hardest to judge accurately. 3) Ongoing analysis is examining the effects of varying heights, displacements, camera angles, and object types on performance in tasks depicted through illustrations. Future applications like free viewpoint video may revolutionize interactive manuals but also enable spatial misconceptions.

1. Perception of Objects in Technical
Illustrations - A Challenge in Technical
Communication
Debopriyo Roy
Associate Professor
University of Aizu
December 12, 2010
Presentation at IEEE PCS-J, Nagano City, Japan

2. 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 a
scene with one eye.
 We perceive depth with 2 main sources of information:
A. Binocular disparity B. Monocular cues

3. Depth Perceptions & Technical Illustrations
 How should technical
illustrators demonstrate
physical orientation to
understand procedures
 What should be the
characteristics of the
display plane for
visualizing procedures?

4. Specific Issues for Technical Writers
 How do we design body/object positions in
user manuals most effectively for second
language speakers such that a minimalist text
approach is viable.
 Would readers in EFL context understand the
subtle difference within body and object
positions /orientations, based on difference in
tasks when explained with minimal English text?

5. Affordance - 1 (Image Plane)
Anatomical Image Plane -
Axial - Image slices that are
perpendicular to the long axis of
the body
Coronal-Image slices that bisects the
front and back sides of the body
Sagittal- Image slices that bisects the
left and right side of the body

6. Affordance -2 (Optimal Perspective)
 Canonical View - Front, side and top views of an object.

7. Affordance - 3 (Task-based)
Orientation of Illustrations Characteristics of Display
Planes
Distance between legs
Weight of the ball
Exact location of the ball
Pressure on the knees
Angle of shoulder bend
Pressure on the shoulder
Angle between hips and legs
Grip to lift the ball
Head Position
Leg fold
Extent of Knee folds
Ankle pressure
Direction of ball lift
Transfer of weight
Displacement during lift
Bend of vertebral column
Overall Camera angle

8. 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 by
the 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.

9. Object Manipulation vs. Physical Orientation
 Research findings suggest
that people use different parts
of their brains when doing
tasks requiring object Ball Grip
manipulation.
 However, the extent of such
use diminishes when doing
tasks requiring physical
orientation of their bodies
in three-dimensional space. Ball
Release

10. Two Dimensional Views of Three
Dimensional Plane
 For on-screen or print
materials, people only
have monocular cues to
help them interpret what
they see.
 This reduction of depth
cues makes
interpretation more
difficult and an
illustration’s point of view
more critical.

11. Object vs. Body-Centered View
 Research has shown that
the effects of mental
rotation depend on point
of view.
 Spectator’s point of view
 Performer’s point of view

12. Perception of Distances
 People are better at judging
distances directly across the
display plane.
 In Figure 1, the height of the
box relative to the man’s waist
is clearly visible. This is
because the distance is across
the display plane.
 However, the distance
between the box and the
man’s chest is not visible
because the movement is into
the display plane.

13. Perception of More Complex Physical
Postures
 In this figure, the
distance between any
two object is recognized
mostly as a function of
other body postures
and parts.
 To understand this
object, different angular
verification along each
of X, Y and Z axis is
required.

14. Illustrations and Instructions
 Heiser and Tversky found (for a
furniture assembly task) that
illustrations showing objects
partially rotated is easier to
understand than objects showed
head on.
 Szlichcinski found illustrations
showing slightly rotated objects to
have more task-based affordance.
 He also found that hand positions in
illustrations are duplicated in actual
tasks exactly as shown.

15. 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

16. Variations of Viewpoints - Body Postures
Height /Angle of Camera Const. -Along
Waistline
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

17. Variations of Viewpoints - Camera Rotation
along waist line (X & Z axis manipulation)
2/3rd Front 1/3rd Side Side 1/3rd Back
Back 1/3rd Back 2/3rd Front

18. Variations of Viewpoints - Z axis
manipulation
Movement along Z axis
Movement along Y axis

19. 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 hold
the box

20. Hypotheses
 Major Research Question -
Previous studies do not
resolve conflict between
orientation of illustrations
versus characteristics of
display plane.
 Illustrations that show a
performer’s point of view will be
easier to use.
 Illustrations that place important
distances across the display
plane will be easier to use.

21. Methods - 1
 Test subjects were asked to evaluate body images via a
matching task.
 20 subjects were tested and each subject rated 20 sets of
images.
 Poser Figure Artist software used to design body positions
and angles. It sustains accurate three dimensional
relationship among body parts.
 Variations of viewpoints and body positions were tested.

22. Methods - 2 (Operation Matrix)
Task # 1: Man with the box

23. Methods - 3 (Operationalization of Trials)

24. Summary of Findings
 Subjects were most confident for images shown directly from
front or back.
 Somewhat less confident of the images rotated one-third
from 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.

25. Ongoing Analysis on Performance:
Accuracy Scores
 Correlation between accuracy rates for different heights
of the box along the Y axis.
 Correlation between accuracy rates for the
displacement types. (Extensive further analysis required
for 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 the
waist / chest.

26. 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).

27. Free Viewpoint - Looking into Future
 Free viewpoint television (FTV) is a system for viewing natural
video, allowing the user to interactively control the viewpoint and
generate new views of a dynamic scene from any 3D position.
 With FTV, the focus of attention can be controlled by the viewers
rather than a director, meaning that each viewer may be
observing a unique viewpoint.
 This technology might revolutionize the way we look at
interactive procedural user manuals. Readers will be able to
switch views as and when they need to, based on task.
 However, this might not necessarily improve procedural
accuracy, because of uncontrolled access to viewpoints,
enabling spatial misconception.

28. Japan’s Promise for WC Football 2022
 Japanese organizers
say each game will be
filmed by 200 high
definition cameras,
which will use
"freeviewpoint"
technology to allow
fans to see the action
unfold from a player's
eye view -- the kind of
images until now only
seen in video games.
(CNN.com - 1st Dec,
2010)

29. THANK YOU !