Psych prelim 2
A 50-foot wall is made with large bricks at the top and small bricks at the bottom. What unusual perceptions are you likely to have for objects at the top of the wall looking down? What sorts of perceptions are you likely to have looking up the wall from the bottom?
Looking at object from the top of the wall looking down will seem farther away, and will therefore be perceived as larger. If you look up at the wall from the bottom, object will seem closer, and will therefore be perceived as smaller.
What is Livingstone's theory regarding the origin of the Mona Lisa's elusive smile?
Most apparent/cheerful when looking away, less when looking directly at. Expression changes based on center of gaze in relation to mouth. Her smile is more apparent in the coarse-information component of the image, and therefore more apparent to the peripheral than to central vision. 71
What is the vergence focus problem? How does this relate to 3D movies and head mounted displays?
Stereoscopic display: all objects lie in same focal plane. Vergeance can fool into percieving objects at diff depths. Screen based steroscopic displays provide no focus info, so that mixed with vergeance = eyestrain. Vergence and focus cross-coupling are also responsible for preventing large depth intervals of 3-D visual space being rendered with integrity through dual 2-D displays.
Explain how to find a complementary color using the CIE diagram. For example, what is complementary to 600 nanometers?
The complementary wavelength of a color is produced by drawing a line between that color and white and extrapolating to the opposite spectrum locus. Adding a color and its complementary color produces white. The complementary color of 600 nanometers (red) is green.
What is wrong with the description of some individuals as 'color blind'?
The problem with describing some people as color blind is that, technically, everyone is color blind. Also, it isn't really color blindness - just color deficiency. About 10% of males and 1% of females have a color deficiency - meaning the 3D color space is actually just 2D. It's also bad because color blindness can disqualify applicants from jobs.
Why do television stations transmit a YIQ color signal to an RGB phosphor television?
- it allows for compatibility with black and white televisions, which use the Y signal. - It also reduces bandwidth because the luminance signal is sent at a higher bandwidth. This reduction of bandwidth is okay because our acuity of color is lower and color will often 'lock' to the borders of the luminance signal
two motion cues for the perception of depth
1. Motion parallax - objects in distance appear to move slower than objects up close (like passenger in a car) 2. Rate of acceleration - D=1/2 at2
Video-linked active glasses
ASKED 1) 2 films taken at 2 different positions 2) Alternate lines show you images for different eyes
If you were flying over New York City at a height of 1000 meters, would a 40 story (120 meters) building produce sufficient depth to exceed the disparity threshold? (assume that you have a 1 cm threshold at 10 meters).
Dtheta = ad/E^2 distance b/w eyes * dist b/w objects/ Dist to obj^2
Why is brown an odd color?
Essentially dark yellow, but requires a reference white to be percieved. Not in color sets.
Shape constancy
Regardless of distance or orientation of object, we percieve same shape. Our brain compensates for the distortion of the shape by taking into account visual cues about distance and depth to keep our perception of the frame constant.
Long Range Apparent Motion
The sensation of motion even when you know it's being sampled.
Persistence
There is essentially no minimum time that you need to see something. It depends on the total number of photons firing (total amount of light). As long as the time the light is on is at least 100 milliseconds, you can detect it. (Time x Intensity > Threshold)
Protanope
They lack the red (long wavelength) sensitive cones, and as a result, struggle to distinguish the green-yellow-red spectrum.
Chromadepth
Very small prism, separates wavelengths by bending light rays
Dichromat
animals which only have two cones, and can only percieve mixtures of these colors.
Pulfrich effect
pendulum moving in plane, but eyes think it is moving in an elipse
Horopter
region of space that projects to corresponding points on the the 2 retinae
McAdam Ellipses
the areas on the CIE diagram where all colors are indistinguishable from the color in the center of each ellipse.
Before the renaissance, what evidence suggests that artists did not have a solid grasp of linear perspective?
The drawings from before the renaissance lacked 3 dimensionality, and the lines did not converge correctly to one point.
Describe four color phenomena that are explained by opponent color theory that are not explained by trichromatic color theory.
- Color naming - why are there no reddish-greens or yellowish blues? Color opponent theory says we have red-ON/green-OFF, red-OFF/green-ON, blue-ON/yellow-OFF etc ganglion cells. - Colored afterimages - when you stare, for example, at a red image, you will see green when you look to a white paper. This is explained by fatigue on the pathways promoting red produce the illusion of a green square. - Simultaneous color contrast-color contrast - Colors that have the same mean of white light may appear drastically different. Or, a change in contrast to an entire image will still make a shirt appear yellow, but when you drop only the shirt into the original picture, it looks green. - Color naming for the color anomalous - For those deficient in one eye: protanopes and deuteranopes say everything appears blue to yellow. For tritanopes, everything appears red to green.
Other than binocular disparity, describe two advantages of having two eyes? Use the concept of probability summation
1) Field of view- greater field of view with two eyes 2) Probability Summation Two eyes: P(two)= 1- (1-p)(1-p)
Provide three guidelines for displaying surfaces.
1. A simple lighting model, based on a single light source applied to a Lambertian surface, is a good default. The light source should be from above and to one side and infinitely distant. 2. Specular reflection in revealing fine surface detail. Because specular reflection depends on both the viewpoint and the position of the light source, the user should be given interactive control of both the lighting direction and the amount of specular reflection to specify where the highlights will appear. 3. Cast shadows should be used, but only if the shadows do not interfere with other displayed information. The shadows should be computed to have blurred edges to make a clear distinction between shadow and surface pigment changes.
two ocular cues for the perception of depth
1. Binocular disparity - The difference between the projections of the world on the two eyes. If objects do not line up on both eyes - crossed disparity - see closer than it is (3D) 2. Convergence - When we fixate on an object, our eyes converge to a degree dictated by its distance. We are only good at the computation of this distance within arms length.
Describe and provide examples of 5 ways to make a spot appear to move.
1. Move the dot 2. Adapt to motion, then observe dot. -Motion aftereffect: When you view motion in one direction over a certain period of time, particular neurons fire, and begin to become reduced in sensitivity (fatigued). When motion stops, you begin to perceive motion in the opposite direction as a result of the neurons being fatigued. The motion aftereffect changes the balance between neurons selective to motion in directions away from and in the direction of the adapting motion. - Can result in underestimation of speed, errors in direction of motion 3. Autokinetic effect: Observe dot without references - In the dark (no reference) a dot appears to move 4. Induced motion: move reference frame so stationary dot appears to move 5. Stroboscopic/apparent motion: - Flash successive dots to create motion (ternus display) - At short distances and fast frame rates, apparent motion = real motion due to limits of temporal and spatial resolution - undersampling = jitters
Provide two lines of evidence that we are especially sensitive to biological motion?
1. We are very sensitive to point light walkers and can easily pull out structure in a moving image with lights on major joints. Additionally, we can tell the age and sex of the walkers. 2. Infants at 4 months can differentiate biological and non-biological movement.
What is evidence that color names are not culturally determined. What did Berlin and Kay show about the evolution of color names?
130,000 people from around the world took a global color survey, and the results show that there is a general consensus in regard to what symbolism particular colors hold. For example, black can indicate mourning or bad luck, while white indicates purity. Berlin and Kay showed that basic color names in a culture are predictable by the number of color names that culture has. They theorize that as languages evolve, they acquire new basic color words in this chronological sequence: Stage 1 and 2- White/black; Stage 3- Red; Stage 4- Green or yellow; Stage 5- Yellow or green; Stage 6- Blue; Stage 7- Brown; Stages 8,9,10,11- Purple, pink, orange, or grey.
What are the advantages of filming at 60 Hz or better? How does this improve the appearance over traditional techniques? What are the disadvantages?
60 Hz marks the threshold for our perception of flicker in a film. Above 60 Hz, we can no longer perceive flicker, so films don't look juttery like in traditional films. Disadvantage = it requires more film and memory
What is a scale composite? Provide an example.
A scale composite is where each actor is shot separately, and the two pieces of film are put together later. This is used with blue screen so that they can be shot at different distances or one scaled down, and still be composited together. Used to make Gimli look smaller than the elves despite being the tallest cast member.
Kinetic Depth Effect
A weird wire can be bent with its shadow reflected, and when you roatate it, the brain sees it as a rigid 3D object, not wiggly 2D line. Because brain assumes objects are rigid in 3D space, and mechanisms of object perception incorporate this.
Name three display problems arising from equiluminous (isoluminant) colors.
ALREADY ASKED 1. For colored text on an equiluminous background- in the part of the figure where there is only a chromatic difference between the text and the background, the text becomes very difficult to read 2. If a pattern is created that is equiluminous with its background and contains only chromatic differences, and that pattern is set in motion, something strange occurs. The moving patter appears to move much more slowly that a black against white pattern moving at the same speed. 3. It appears to be impossible, or at least very difficult, to see stereoscopic depth in stereo pairs that differ only in terms of the color channels
Use projection theory to explain why a 3-D movie can produce a constant depth (when measured in terms of the percentage towards or away from the viewer) independent of where the observer is in the room.
ALREADY ASKED Binocular disparity: difference between the project of the world on the two eyes, ability to perceive objects at different depths
In terms of chromaticity and luminance discuss the limitations of the range of possible colors on television, film and the real world.
ALREADY ASKED In the real world, white is the brightest light, and all other colors are less bright. So a white light has 765 total light, but a blue light only has 255 total light. In film, white light is created by not filtering out light, while all other colors are created by filtering light. This is okay, because white is also the brightest color in the real world. TVs Restricted by RGB triangle - mosly uses three phosphors. Possibly 4 for better yellows. Digital are restricted by number of samples, but you can't tell the difference
Provide three examples and applications of Gestalt laws to displays.
ALREADY ASKED Proximity: Close together = perceptually grouped together. Place things about related info close together. Similarity: Similar elements grouped together. Code rows or columns with low level visual channel properties like color or texture Connectedness: Connect graphical objects by lines. Shows some relationship.
What is tilt-shift photography? How does it work? Why does it work?
ALREADY ASKED Uses tilt-shift lenses to overcome the restrictions of depth of field and perspective that normal lenses provide. A tilt-shift lens allows for the rotation of lens against the image plane (tilt), as well as the movement of lens along the image plane (shift). By applying Scheimpflug principle (describes orientation of plane of focus of opt system when not parallel to plane), tilt-shift photography is able to obtain a very shallow depth of field using tilt and a large aperture.
What is the relation between spatial resolution, temporal resolution and velocity, for the perception of movement in time sampled displays like cinema or television.
ALREADY ASKED Velocity up, spatial resolution down Full acuity = velocity of 2 degrees/sec. If you have short distances and fast frame rates, apparent motion is equivalent to real motion. The limits of temporal and spatial resolution make apparent and real motion indistinguishable.
Anaglyph
ASKED 1) Film from 2 points, in black and white 2) Project one image through colored film, second through other Disadvantages: "ghosting"
Passive polarization
ASKED 1. Two films taken at two different positions 2. Two films projected through polarizers onto silver oxide screen (normal screens do not maintain the polarization) 3. Audience must wear polarized glasses Advantage: large audience, motion, color Disadvantage: expensive screen, ghosting, polarizers reduce intensity
Lenticular lenses
ASKED Little lenses, for example on 3D postcards. Advantages: no viewing equipment required, inexpensive Disadvantages: fixed viewing distance
Pulfrich phenomenon
ASKED Pendulum moving in plane, eyes think it moves in ellipse. Advantages: inexpensive viewing equipment, one camera needed, Disadvantages: requires choreographing (front side always move left, back alwawys moves right)
Stereoscope
ASKED Two images for each eye to create one image (think mickey mouse toy in class) Advantages: no ghosting Disadvantage: only one viewer, static, viewing equip needed
Auto-stereogram
ASKED Use periodic patterning.
Variable mirror
ASKED Vibrating mirror reflecting monitor Advantages: no viewing equipment required, full color possible Disadvantages: very expensive viewing equipment
Relative vs. Absolute Depth Cues:
Absolute - measure of depth in units Relative - depth position compared to other objects in scene
What is the difference between additive and subtractive color mixture. How do metamers with paint behave relative to metamers with added light?
Additive color mixing: When certain pairs of lights are mixed, white light is created, because all three of our cone types are activated in approx. equal proportion. Subtractive color mixing: When absorbances are mixed. This is because the molecule are so close together that light would hit both pigments. Metamers with paint when mixed normally behave subtractively. Their absorbances are added. For this reason, a paint that absorbs red and green and and paint that absorbs green and blue would reflect nothing, and appear gray. Metamers with light when mixed behave additively. Their reflectances are added. So if a light that reflects red, one that reflects blue, and one that reflects green are mixed, it will look white.
How many colors can I produce with an 8 bit look up table and 6 bit DACs (digital to analog converters)?
An 8 bit look up table can produce 256 colors (2^8), and a 6 bit DAC can produce 262,144 colors. (2^6*2^6*2^6). So you can put up 256 out of the possible 264,144 colors.
What is the difference between LUV (UVW) and XYZ color space?
An LUV color space is a sensitivity oriented color space, while the XYZ, or CIE color space is not. LUV coordinates result in more equal size ellipses, and as a result, there is similar discrimination ability across the chart.
Benhams top
An illusion with a spinning disk with arcs of black. Everyone sees different shades as this spins.
What is anamorphic art?
Anamorphic art appears to be a stretched image, but looks 'normal' when viewed from an extreme angle
Bruneleski in 1413 described what primary aspect of linear perspective.
Bruneleski said that parallel lines appear to recede in the distance and converge at the vanishing point.
Describe a color matching experiment that proves that the entire color space is 3-dimensional (can be described in terms of three variables).
C = rR +gG+bB When three projectors are set up with overlapping beams, any color can be created by varying amount of light produced by each.
What is represented by a confusion line?
Colors that appear to all be the same.
metamer
Colors that match apparent color of objects with different spectral power distributions. Very common in neutral or dark colors.
What is "display efficacy" (DE)? What is "visual efficacy" (VE)? Why is DE never 100% with current technology? (W. p.56)
DE = how efficiently a display is being used. Ratio of uniquely stimulated brain pixels to screen pixels (USBP to SP) VE = Ratio between USBP and TBP (total brain pixels) Tells proportion of BP getting unique info DE is never 100% with current technology because in order for this to happen, there would have to be one screen pixel for every brain pixel, but screen pixels are uniformly distributed and brain pixels are not.
Provide an example of an artificial spatial cue. Why are these used?
Effective ways to provide info about space not based on how info is provided in norm environ. ex: proximity luminance covariance. Varies color based on distance from viewpoint. More distance objects are faded to become the light or darkness of background.
Relate Emmerts law to the perception of afterimages
Emmert's Law: perceived size = k* perceived distance Afterimage: Retinal image is constant, visual angle is constant They appear to increase in size when projected on further distance
According to Livingstone, why do equiluminant colors look unusual?
Equiluminant colors may generate a sense of vibration, motion, an eerie quality because the 'what' (ventral) system can see something that the 'where' (dorsal) system cannot. We are able to identify a particular object, but not its position and motion. Page 66.
Why were the miniatures so large in Lord of the Rings?
FIND A
What is forced perspective? How does it apply to the filming of Frodo and Gandalf together on the cart in Lord of the Rings. Why does motion of the camera make this difficult? What is the solution?
Forced perspective is where, in order to make someone appear smaller, you film them further away than something else. Filming Frodo and Gandalf, if you wanted them both to appear 10ft from the camera, you had to have Frodo stand 1.333x further away, as that is the inverse of their expected size ratios. (Frodo should look .75 as tall as Gandalf) Thus, in a scaled cart, Frodo sat further away in the cart. This is meant for static cameras. With motion, it is easy to tell they are at different distances. For motion, you need motion control - one actor is also on a moving platform that moves when the camera moves to maintain the illusion.
High vs. Low Thresholds for motion
High threshold for motion = how fast something can move and still be visible low threshold for motion = the idea that an object is perceived at 10 to 20 minutes of arc/sec without a reference, and 1 to 2 minutes of arc/sec with a reference.
What is the relation between the high threshold for motion and visual acuity? How fast must something move before one loses the ability to resolve spatial detail?
High threshold for motion is how fast something can move and still be visible. As the threshold for motion increases, acuity decreases. A velocity of up to 2 degrees per second will result in full acuity, but any faster, spatial acuity decreases and you won't get information of spatial details.
Why does CIE use 'imaginary' primaries? What is represented by the points outside of the CIE chart?
Imaginary primaries are coordinate axes outside of the color space. They are used so that all colors can be in terms of positive coordinates.
How does one make a three-dimensional postcard?
LENTICULAR LENSES: little lenses on the postcard (make the scratchy sound)
Tritanopes
Lack short wavelength cone. See these colors as greenish or black. Very rare.
Simultaneous contrast
Looking at two colors side by side changes our perception of each of them
What are the differences between luminance, lightness, and brightness?
Luminance = measured amount of light coming from some region of space. It is measured in units such as candelas per square meter. Of the three terms, only luminance refers to something that can be physically measured. Brightness = perceived amount of light coming from a source. Lightness= perceived reflectance of a surface. A white surface is light. A black surface is dark. The shade of paint is another concept of lightness.
What technologies use additive color mixture? Which use subtractive color mixture?
Magazine printings utilize both types of mixing because sometime the dots overlap. Typical paintings use subtractive mixing. Pointilism, much color printing, and conventional painting (where regions of color opposing each other are larger than a color-opponent cells receptive field) use additive mixing, as they are actually made up of tiny dots of different colors side by side to look like a different color.
How does one make an Ishihara color test chart that finds protanopes and distinguishes them from deuteranopes?
Making a normal Ishihara test: Find two colors along a color confusion line for the test in question Using spots, make the number in one color and the background the other. Vary sizes and intensities. Optional: Make a number of lower contrast that is visual to subject of this test. Pick a color at an intersect of their confusion line and make the background another color along one of those confusion lines
Ternus Effect
Neurons in the visual cortex show direction sensitivity, and this selectivity can account for long range apparent motion due to the Ternus Effect, in which blinking dots give the perception of motion if the temporal gap occurs at just the right rate. The perception of motion from left to right or vice versa is perceived. prob not on exam
Explain the concept of negative primaries in a color-matching task.
Negative light is when light must be subtracted to arrive at a particular coordinate location. A subtractive filter involves the overlap of light passing through two colors. R: -10, G:30, B:30 a1lambda1 = G+B-R R+a1lambda1=G+B YOu can use negative R added to other side to create a match
Describe four depth cues that can be used to help navigate a web page.
Occlusion = one object overlaps or occludes another, and thus appears closer to the observer. This is probably the strongest depth cue. In web pages, overlapping windows rely on our understanding of occlusion to be effective. Shading models are using in computer graphics to represent the interaction of light with surfaces. There are four basic components: 1. Lambertian shading = diffuse 2. Specular shading = specular 3. Ambient shading (light coming from the surrounding environment 4. Cast shadows (shadows cast by an object either on itself or on other objects). 3D widgets Cast shadows = indirect depth cue. Shadow locates the object with respect to something else. Mouse on screen? Surface texture allows us to distinguish one transparent curved surface from another transparent curved surface lying beneath it.
Describe the relation between Panum's fusional area, diplopia and perceived depth. How does this vary with eccentricity?
Panum's functional area: #D area where objects can be fused and seen without double images. Worst case: little depth. At fovea,there is only 1/10 degree before fusion breakdown, but at 6 degrees eccentricity it is 1/3 degree.
four pictorial cues for the perception of depth
Pictorial cues: 1. Familiar size - WHen objects we see have a known size, it affects distance perception. We know German Shephards and chairs are similar size, so we see at same distance. But tiny dog looks like a further distance. 2. Atmospheric Perspective - things in the distance appear to have lower contrast and are bluer 3. Linear perspective - Lines should converge to a vanishing point. IE railroad tracks or the edges of a chair 4.Depth of field - The range of distance that looks sharp. Increased by decreasing apeture
What is the difference between protanomolous and protanopia?
Protanomaly is "red weakness", or reduced sensitivity to red light. This can range from almost normal vision to nearly absent perception of red. They have all three cones, but the red cone is faulty and perceives light out of alignment. Protanopia have only blue and green cones. They are entirely unable to perceive red.
Why is pseudocoloring sometimes used for displays? What does Ware recommend (provide two) for the choice of colors? Why can red/green pseudocoloring be a problem?
Pseudocoloring is the technique of representing continuously varying map values using a sequence of colors. Two colors that Ware recommends are yellow (which has a very high luminance, almost equal to white) and blue. Red/green pseudocoloring can be a problem to individuals who suffer from protanopia and deuteranopia, both of which cause an inability to discriminate red from green.
In which ways is a color television restricted in its color capabilities. How does this change for a computer screen with the same phosphors
Restricted by RGB triangle - mosly uses three phosphors. Possibly 4 for better yellows. Digital are restricted by number of samples, but you can't tell the difference They are now the same.
Use size/distance theory to explain the moon illusion and the illusion that cars look like toys from the air.
Size distance theory: If you see it as smaller, the closer they are perceived. If you see it as larger, the farther away it is perceived. Moon illusion: The moon on the horizon looks bigger than when it is seen straight up in the sky. We percieve it as further away (depth cues), so then it must be bigger! Cars like toys: no depth cues so they look closer than they actually are. See it as smaller.
You are watching a King Kong movie where a 10-story building falls in one second. What are you likely to see? If the original miniature was only 1 meter high but the building was intended to look 36 meters high, what do you do about the film rate?
Size ratios and film speed. FS = sqrt(intended size/actual size) FS = 6, so slow down the falling by filming it 6 times faster, and then showing it at the original speed
Describe the steps for making a random-dot stereogram.
Start with an image filled with random dots Select a region and slightly shift it horizontally
What is the advantage of CIElab and CIEluv over standard XYZ color space? What is the difference?
The CIE XYZ color space is not perceptually uniform. Thus, in 1978, the CIE produced a set of recommendations on the use of two uniform color spaces that are transformations of the XYZ color space. These are called the CIElab and the CIEluv uniform color spaces.
Describe the relationship between 'shape from shading' and the position of the light source.
The more on the bottom the shadow is, the more it seems like its popping out. On the top, it seems sunken in. We assume lighting comes from above
Why is this painting important in the history of art and the use of depth cues.
The painting demonstrates multiple vanishing points of perspective.
On a graphics terminal you have created the image of a large rock on a field. The rock is intended to look 2 meters high. If the rock perceived as being much closer that you anticipated, what will happen to the perceived size?
The perceived size will be smaller than 2 meters high. Because it is still looking like 2m and then you are closer, so it must be smaller at old distance.
What are the three primary dimensions of texture?
The three primary dimensions of texture are: Orientation O: the orientation of the cosine component Scale S: the size-1/(spatial frequency) component Contrast C: an amplitude or contrast component
What does a tritanopic confusion line represent?
The tritanopic confusion line is represented by the lines radiating from the lower part of the CIE Lu'v' UCS diagram. Colors that differ along these lines can still be distinguished by the great majority of color-blind individuals. Colors not differentiated by tritanopes
What are categorical colors? How is this related to color confusion? How is this relevant to displays?
They are defined in terms of their differences from the ideal. Colors closer to ideal red, etc are easier to remember Confusion b/w color codes is affected by color categories - you take longer to identify presence or absence of a chip if surrounded by elements of diff color but same catefory. Only a small number of colors can be labels.
In the video showing two lamps playing with a ball, why do the lamps look alive and seem to have personality?
They exhibit biological motion. A factor that these lamps portray that allows them to have biological motion is the fact that changes in acceleration are minimized. For example, jerk is minimized when a person, or lifelike object, jumps upon the landing. Additionally, speed is inversely related to the curvature. Lastly, the lamps move in accordance to the idea that mass is proportional to height x width x length. The combination of these factors allows the lamps to not look so rigid.
Deteranope
They lack the green (medium wavelength) sensitive cones. As a result, they struggle to distinguish the green-yellow-red spectrum.
What does work with point light walkers tell us about our perception of biological motion?
This website shows a cool demo of this experiment- http://www.biomotionlab.ca/Demos/BMLwalker.html. When the stimulus is in motion, the individual dots provide fully correct motion signals. Therefore, many studies have concluded that biological motion perception is derived from local motion signals. We can percieve sex, mood, etc.
Explain why Johnny Lee's demonstration of depth on the Wiiis so powerful. http://www.youtube.com/watch?v=Jd3-eiid-Uw
Using the infrared sensing on the remote, he is able to detect the users point of view and adjust the targets on the screen to always appear 3D, without aid of glasses. You can often even see somewhat behind them.
Describe a perceptually perfect (i.e., efficient) visual display.
Visual field - 180º horizontal, 160º vertical (handheld would be less) Intensity range - 10000-20000:1 Number of intensity levels: 10 bits (1000 levels) - determined by image type, gamma, screen range Visual acuity/resolution: 100 px(lines)/degree Temporal acuity/frames per second: Depends on stationary or fast motion. You need higher frame rate for fast image. But general rule is around 100 frames/second. Colors in the far distance should be more faded and have more blues. Color: Should use phosphors further apart in CIE chart. Add a third, fourth, fifth, etc color. More real phosphors = better CIE Motion: Blurring of the periphery and background during motion will give a sense of smoother motion. No jitters. Large and heavy objects should move appropriately and fall with regard to their size.
How can the rate of falling act as a depth and size cue? How does this relate to filming miniatures?
Visual gravity cues contribute to perception of absolute distance and size of falling object. How to make minis look full size? Scene must be filmed at sqrt(desired/actualsize) and projected at normal time to look like time of fall relates to square root of fall height.
Section 508 of the Rehabilitation Act restricts the use of flicker on websites run by federal agencies. Why? What range of frequencies?
Websites should be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz because otherwise they could cause pattern-induced epilepsy or other medical issues, such as convulsions and vomiting of blood.
Use a space/time plot to explain why blur is sometimes introduced into movies with fast motion?
Will give sense of smoother motion and avoid the image looking like it is jumping. Blurring in direction of motion can reduce sampling artifacts Spatio-temporal anti-aliasing
Provide examples of depth cues used a.) at only close range b.) at only distant ranges c.) at all ranges
a. convergence, disparity, accomodation b. atmospheric perspective c. familiar size??
Describe an example of how "point of view" was used by Mantegna.
achieve a sense of drama by pushing the spectator closer than one wants to be. The wormhole effect, or the painting of Jesus
Provide two examples of art that take advantage of the acuity limitations in the visual periphery. (Livingstone)
· Monet's Rue Montorgueil in Paris, Festival of June 30, 1878 The painting includes blurring, which "reflects the way in which our peripheral vision works." The spatial imprecision in the painting is actually consistent with a single glance, mirroring our acuity limits. Page 74. · Madame Henriot (1876) includes a woman in the foreground with a detailed and high contrast face, but her extremities and the background is noticeably blurrier, reflecting the resolution of our visual system when we focus on an object in the foreground. Page 81.
