Abstract
Human depth perception involves complex visual and brain functions. Depth perception in desktop virtual reality has become more important given the uses of such spaces for learning, training, collaboration, simulations, showcasing work, and conducting research on human behaviors. This chapter involves a meta-analysis of the extant research on human depth perception in virtual worlds. It posits some early design concepts for both the creation and evolution of such spaces but also their deployment for educational purposes.
TopIntroduction
Desktop virtual reality is a critical part of electronic gaming, online learning, human socializing, entertainment, and simulation learning. While this type of 3D space is created through illusory design and phi phenomenon of illusory motion on a 2D screen, the experience of dimensionality and depth perception is an important part of this immersive virtual experience. The perception of depth in these synthetic spaces is important for image fidelity and imagistic realism; effective collaboration with other human-embodied avatars co-building 3D objects; and proper interfacing with other devices (including haptic ones). More accurate depth perception may enhance the uses of virtual environments for the study of real-world human behavior—such as research about children’s road-crossing behaviors or adult collision-avoidance behavior. Improved depth perception design may result in more effective virtual walk-throughs of designed spaces that may be equivalents of physical spaces and may increase utility (Kuhl, Thompson, & Creem-Regehr, 2006). Virtual depth tasks, such as tele-surgery, 3D co-design, and avatar interactivity, require accurate human depth perception.
Proper depth perception may enhance the user’s experiences in immersive spaces. Proper calibration may help them avoid simulator sickness (Bigoin, Porte, Kartiko, & Kavakli, 2004), learned mal-adaptability to real spaces, and “ocular stress” (Alexander, Conradi, Winkelholz, 2003, n.p.) or eye discomfort. Having proper calibration of the virtual reality medium may avoid negative and incorrect adaptations to depth sensations (Kuhl, Thompson, & Creem-Regehr, 2009, p. 19:2) in real spaces. These corrections may also enhance the human ability to immerse longer in desktop virtual reality spaces.
This chapter will provide a brief overview of human visual perception in real environments. Then, it will show the differences of visual perception—particularly depth perception—in desktop virtual reality environments. This will summarize the challenges of creating depth perception in online spaces and look at current strategies. This will also explore some potential future areas of development to enhance human depth perception in virtual spaces.
Key Terms in this Chapter
Psychophysics: The empirical, rigorous, and experimental study of the human mind and perceptual systems, resulting in quantitative findings
Chromaticity: The quality of color based on its dominant wavelength and its purity
Plane: A flat or level surface
Amodal completion: The sense of perceiving occluded parts of an object
Occlusion: The covering up or the obscuring of an object by another which obscures the backgrounded object from full view; occlusion may be static as in a still image, or it may be dynamic as in a temporary moving occlusion
Naïve realism: The inaccurate perception that the world is exactly as it is perceived (discounting illusions, misperceptions, inaccurate interpretations, and so on)
Volumetric: Indicating measurement by volume, mass, or quantity
Ecological optics: The physical aspects of light that are relevant to the perceiver in the environment
Orthographic: Involving true right angles or perpendicular lines
Environment: The full surroundings, an ecology
Recognition by components or “RBC”: The structure-based theory of human visual perception that suggests that the eyes and mind break down an object into component parts that may then be recognized as a particular aggregated object; the theory that people first ascertain the edge of an object, then its non-accidental properties and regions of concavity, then the component parts, and then a matching of the components to “object representations,” which leads to object identification
Convex: Having a surface that is curved outward, protuberant
Sensation: A mental condition or physical feeling caused by a sensory stimulation
Invariant: The concept of unchanging patterns or constants in an environment that retain their basic qualities in an environment no matter how that item is viewed or “sampled” from various angles; the qualities of invariants may be expressed through the laws of physics and is quantifiable mathematically; these may include the properties of sizes, brightness, and shapes
Luminosity: The brightness of a light or color
Concave: Having a surface that is curved or hollowed inward
Geons: Geometrical ions, the concept of geometrical primitives
Attentional resource: The concept of human perception as a limited resource that may be deployed in particular ways for particular effects
Illusion: A visual perception that does not accurately represent reality
Anisotropic: Of unequal physical properties along different axes
Orientation: The sense of position in a particular physical or virtual context
Cross-section: An image of the interior of an object cut by a transverse plane at right angles to the longest axis of the object
Illusory contour: The implied lines of a shape without the actual definition in terms of a filling in of the shape or the outlining of a shape
Saturation: The state of being fully imbued or soaked
Aspect Ratio: The width divided by the height of an image (usually denoted by ratios of whole numbers)
Metamers: Objects that are perceptually indistinguishable from each other even though they are physically different (but with insufficient differences for the perceiving conditions); may be confused based on distance or dim lighting, for example
Perceptually invisible objects: Objects that may be observed by the sensory systems of an individual without his or her conscious awareness of the registering of that object or sensation
Intensity: The energy or strength of a stimulus
Action Potential: Neural nerve impulses
Termination: The closing off of a line via convergence or truncation
Perception: The faculty of gaining sensory information from the environment, such as through the sensory organs related to sight, smell, taste, touch, and hearing
Model: A representation of a thing from the real world
Egocentric distance (absolute distance): The distance from an observer to an object
Transduction: The conversion of a thing to another form, such as energy or messages
Representation: An expression of an idea or object or entity
Constancy: The nature of being unchanging
Prims / primitives: Atomistic or elemental building units of visuals in immersive spaces, the “atoms of perception” in virtual 3D spaces (such as cylinders, spheres, cones, and other 3D shapes)
Axis: A line around which a structure (a form, area, or plane) may be organized; a principal line of movement or direction
Blur: A lack of focus in the viewing of a particular object
Texture: The tactile quality of a surface; the characteristic structure of a material; surface quality
Solipsism: The concept that the world doesn’t exist outside of a person’s perceptions or experience
Inference: The arrival at a conclusion with only partial information but with some degree of probability
Resolution: The quality and degree of sharpness of an image (measured as pixels per inch)
Cotermination: Having a common boundary; contiguous, bordering
Motion parallax: The different images projected on the retina based on movement by the observer when viewing stationary objects at different distances
Near senses: Taste, touch, and smell or those perceptual tools that may collect environmental information up close
Geometry: A branch of math dealing with lines, angles, shapes, and figures, and properties of spatiality
Transparency: The state of being non-opaque, partially see-through
Perceptual constancy: The fact that the perceived properties of objects—such as size, color, and shape—may be perceived as the same even with changes in lighting, perceptual angle, and other environmental elements
Aliasing: A jagged distortion in diagonal lines and curves particularly in images with low resolution
Stimulus: Something that evokes a response
Far senses: Sight and hearing, or those sensory aptitudes that may collect information from a distance (relatively speaking)
Optic array: The light information from a particular situation that reveals the spatial layout, the objects and their respective motions
Vertices: The highest point of a thing from its base; the farthest point from a base; a point in a geometrical solid common to three or more sides; the intersection of two signs of a plane figure (a feature of 2D and 3D shapes that is critical for shape recognition)
Spatial Frequency: The amount of repetition of a form across a set unit of spatial distance
Retina: The interior back portion of the eyeball that receives the image produced by the lens
Autostereoscopic: The concept that each eye of a user sees different images from the same visual stimuli and so may be melded to form a 3D image from the 2D visual captures on the human retina
Coaxial: Passing through or lying on the same line; containing a common line
Deformable: Able to be reshaped or changed in form; transformable
Extrapolation: The projection of visual information beyond where the data would lead
Object: A thing which may be perceived as a whole; a digital artifact that many be manipulated
Isotropic: Of equal or same physical properties along different axes, a texture without a dominant local orientation
Depth perception: The relative distance between one object and other, the distance between different parts of a single object (which draws on different sources of optical information)
Salience: The quality of being striking or conspicuous; importance
Non-accidental: The feature of not occurring naturally and in unintended ways
Bistability: The spontaneous visual perception change of a 3D image that may be interpreted ambiguously (such as in a convex or concave way); perceptual flip
Reflectance: The ratio of reflected light to the radiation on a surface (based on wavelength distribution)
Schema: A plan or diagram