Week+Two


 * __RESOLUTIONS & DISPLAYS__ **

Sensory = brain process of perception Arbitrary = learned with no perceptual basis
 * Symbols**

Sensation = excitation of sensory receptors – low level Perception = process of creating interpretation for sensations – high level

Model of perceptual processing Stage 1: parallel processing - Extract level properties of visual scene = sensation - Rapid involuntary attention to particular features of environment (stimulus) - Processed by neurons in eye and primary visual cortex in the back of the brain

Stage 2: pattern perception - Divide visual fiend into regions and simple patterns (contours, colour, texture) - Active but not conscious processes = receive info that you are unaware of - Specialized for object recognition, environment interaction - Two visual system hypothesis
 * One system for locomotion and eye-hand coordination (action system)
 * One system for symbolic object manipulation (‘what’ system)

Stage 3: Sequential goal-directed processing - Perception holds objects in visual memory by demands of active attention

Ecological optics - Ambient light strikes and obj is reflected to the eyes - Ambient optical array (i.e.: used in raytracing)
 * All light reaching a point
 * Changes over time as viewpoint moves
 * Motion perception of the flow field is built in to develop not consciously constructed

Preattentive processing and illusions - Misleading perception = optical illusion - Impossible to build (i.e.: mobius strip) - Relies on conscious processes to figure it out

Types of shading for paint model surfaces - Lambertian diffuse = overall shape perception - Specular = showing small and fine details - Shadow = one light source reveal reflective heights of objects

Acuities = measurement of ability to see detail - Grating acuity (1-2 min of arc) = ability to distinguish bright and dark bars on a gray background - Point acuity (1 min of arc) = ability to resolve 2 distinct point targets (. .) - Letter acuity (5 min of arc) = ability to resolve letters (i.e.: eye chart E) - Stereo acuity (10 sec of arc) = ability to resolve obj in depth (i.e.: angles V) - Vernier acuity (10 sec of arc) = ability to see if 2 lines are collinear (-_)

Visual field and immersive displays - Sense of engagement by the user (i.e.: virtual reality) - Data wall (i.e.: movie theater) = wide, multiviewers, stereo sound

Spatial contrast sensitivity function - Grating luminance = light intensity varies over distance (i.e.: sine wave grating pattern) - Spatial frequency – left to right, stress on brightness and contrast

Visual stress - caused by repetitive flashing light (i.e.: striped patterns in cartoons) = seizure Aliasing = attenuating effect to smooth out pixelations (i.e.: slanted line)