3D Display Perception and Depth Cues

Chapter 4. Spatial Display

Three Dimensions and depth

Engineering Psychology and Human Performance

Seo-Jung Ko, industrial Engineering , Hanyang University.

Contents
1. Three dimensions and depth

2. Depth Judgments
Object-Centered Cues
Observer-Centered Cues
Effect of Distance on Cue Effectiveness.

3. Perceptual Hypotheses and Ambiguity
faulty assumptions
solutions

4. three-dimensional displays of three-dimensional space
Focused Attention and Artificial Frameworks
Resolving Ambiguities.
Stereoscopic Displays


contents

2. Depth Judgments

faulty assumptions
solutions



Three dimensions and depth
definition
 there are situations in which a third dimension on a display is represented as depth
, or as the perceived distance from the observer along an axis perpendicular(=vertical) t
o the plane of the display.

 These displays are intended to represent three dimensions of Euclidean space

two general purposes

① a display is constructed to guide the pilot in a flight path, or to plan the 3D trajectory of
a robot arm manipulating hazardous material.

② The display may use the third (depth) dimension to represent another (non-distance)
quantity.

To understand the advantages and costs of 3-D displays

① the causes of certain systematic distortions왜곡 in our ability to use depth in the natural world

② some of the fundamental characteristics of perceiving depth.


contents


2. Depth Judgments
Object-Centered Cues : Characteristics of the object or world we are perceiving depth.
Observer-Centered Cues : Characteristics of the human visual system.

faulty assumptions
solutions



Depth Judgments

1. Linear perspective

2. Interposition

3. Height in the plane

4. Light and shadow

5. Relative (familiar) size

6. Textural gradients

7. Proximity-luminance covariance

8. Aerial perspective

9. Motion parallax


Depth Judgments

1. Binocular disparity

 The images received by the two eyes, located at slightly different points in space, are
disparate. The degree of disparity provides a basis for the judgment of distance.

 known as streoscopic displays .

2. Convergence
 “cross-eyed사시” required to focus on objects as they are brought close to the observer,
is necessary to bring the image onto the detail-sensitive retina망막 of both eyes.

 Proprioceptive고유감각 message from the eye muscles to the perceptual centers of the brain
inform the latter of the degree of convergence, and therefore of and object’s distance.

3. Accommodation

In this case the muscles adjust the shape of the lens수정체 to bring the image into focus on th
e retina망막.


Depth Judgments
Effect of Distance on Cue Effectiveness

Not all the cues are equally effective at different distance.

Of course, the range depicted in the figure is based on natural viewing situations and doe
s not necessarily apply when depth is synthesized in displays.
For examples, stereoscopic displays can be used to represent differences in the distance of o
bjects that are miles away.


Perceptual Hypotheses and Ambiguity
Perceptual hypotheses and assumptions

• We often speak of depth and distance perception as governed by perceptual hyp
otheses about the way things are, based on our assumptions.
• These hypotheses and assumptions reflecting top-down processing are relativ
ely automatic and unconscious.

Examples of faulty assumptions

1. a study by Eberts and MacMillan(1985) of the causes of rear-end collision.
 The frequency with which small cars are rear-ended is greater than that for large cars.
 They reasoned that drivers’ judgments about how far a car is in front, and there
-fore how soon they must apply the brakes, are based on the cue of relative size.
큰 차 : 상대적으로 가까이 있는 것 같아 보임. 브레이크를 일찍 밟는다.
작은 차 : 상대적으로 멀리 있는 것 같아 보임. 브레이크를 늦게 밟는다.

2. Figure 4.16
3. Figure 4.17


Perceptual Hypotheses and Ambiguity
Examples of faulty assumptions

solution

Figure 4.16 의 경우, 계기판을 주시
Figure 4.17 의 경우, separated 그래프에도 눈금을
표시하여 원근감에 따른 길이 기준을 설정

권장 고도 그렇더라도, 3차원에서 정확한 거리 판단 시
체감 고도 =조정 고도 깊이는 사용하지 않는 게 효과적.

체감 수평면 실제 수평면 Seo-Jung Ko, industrial Engineering , Hanyang University.

three-dimensional displays of three-dimensional space
Effective of 3-D displays

• a three-dimensional display representation is more compatible with the operator’s
mental model of the three-dimensional world than a two-dimensional counterpart.

• 3-D human form graphic was more effective than 2-D views when complex, asym
metric postures were assessed –postures that would require integration of infor
mation from all three spatial공간의 dimensions.


Effective of 3-D displays

• a three-dimensional display representation is more compatible with the operator’s
mental model of the three-dimensional world than a two-dimensional counterpart.

• 3-D human form graphic was more effective than 2-D views when complex, asym
metric postures were assessed –postures that would require integration of infor
mation from all three spatial공간의 dimensions.

Two limitations relative to their two-dimensional counterparts

① three-dimensional displays are not effective displays for focused attention tasks.
② three-dimensional display generate false hypotheses.
Resolving Ambiguities



• Three-dimensional representations in a two-dimensional display plane are inhere
ntly ambiguous in specifying absolute distances and depth.
ex) figure 4.17의object display 보다separate display가 얼마나 수행하기 나은가.
figure 4.19.a) 의 항공기 예측 상징은 비행경로 밑으로 얼마나 멀리 있는가.

• A potential solution to this limitation may be offered
by incorporating artificial frameworks into the display.



false hypotheses to be formed about depth and distance
because the necessary cues for depth perception are not incorporated into the display.

textural gradient

error of display interpretation

logical solution would be to incorporate additional redundant depth cues, such as the cues of interp
osition (hidden lines) and textural gradient shown in figure 4.20.c

The study of cue dominance

• the addition of cues, particularly in computer-driven dynamic displays, can be expe
nsive and should be avoided if they are unnecessary.
 The study of cue dominance
:: interposition, motion parallax, and binocular disparity



a relatively accurate sense of three-dimensionality can be created
through stereopsis입체시, presenting slightly different images to the two eyes.

Advantage of Stereoscopic Display
1. adding stereo to a perspective display for judgments of azimuth방위각
and elevation of computer-generated objects.

2. time : adding binocular disparity information reduced response times.

But..
편광안경 등 전문적 장치 필요. 열악한 관찰조건. 낮은 강도, 해상도
2차적 원근 디스플레이에 비해 이점이 거의 없음 끝

In Chapter 5, we will focus on interactive displays that are also spatial, and
the nature of the navigational tasks that often use such displays.(map)


3D Display Perception and Depth Cues

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