VR - Visual perception
Visual perception is the brain's ability to interpret and make sense of the information received through the eyes
In this lesson, you will be introduced to the perception of depth, color, motion.
Core ideas of this lesson
How do our brains interpret the world around us so effectively in spite of our limited biological hardware?
Under what conditions will it succeed or fail?
This topic covers perception of the distance
It explains how we perceive motion
Also, it covers the perception of color
Perception of depth - topic
This section explains how humans judge the distance from their eyes to objects in the real world using vision.
Visual examples
This painting uses a monocular depth cue called a texture gradient to enhance depth perception.
(“Paris Street, Rainy Day,” Gustave Caillebotte, 1877. Art Institute of Chicago.)
The Ponzo illusion: The upper red bar appears to be longer, but both are the same length.
The Muller-Lyer illusion: The lower horizontal segment appears to be shorter than the one above, but they are the same
length.
Match the terms with the images they associate with.
texture gradient
the Muller-Lyer illusion
Monocular VS stereo cues
A piece of information that is derived from sensory stimulation and is relevant for perception is called
a sensory cue or simply a cue.
If a depth cue is derived from the photoreceptors or movements of a single eye, then it is called a monocular depth cue.
If both eyes are required, then it is a stereo depth cue.
Explaining monocular and stereo cues
Explaining monocular and stereo cues
True/False question
The cues used by humans also work in computer vision algorithms
to extract depth information from images.
What is visual perception? (pick one answer only)
What are the visual signals that help us perceive depth?
If a depth cue is derived from the photoreceptors or movements
of a single eye, then it is called a _ .
If both eyes are required, then it is a _ .
stereo depth cue
monocular depth cue
Perception of motion - topic
VR systems have the tall order of replicating these uses in a virtual world in spite of limited technology. Just as important as the perception of motion is the perception of non motion.. For example, if we apply the VOR by turning our heads, then do the virtual world objects move correctly on the display so that they appear to be stationary? Slight errors in time or image position might inadvertently trigger the perception of motion.
Essay question
Explain the term: saccadic suppression.
Essay question
On what depends how many frames per second are appropriate for a motion picture?
Stroboscopic apparent motion
Nearly everyone on Earth has seen a motion picture. The motions we see are an illusion because a sequence of still pictures is being flashed onto the screen. This phenomenon is called stroboscopic apparent motion; it was discovered and refined across the 19th century.
True/False question
Color perception is same for all people.
Perception of color - topic
Color perception is unusual because it is purely the result of our visual physiology and neural structures. Mixing colors table:
| color | +second color | product color |
|---|---|---|
| red | blue | purple |
| red | yellow | orange |
| red | green | brown |
Color spaces
One of the most common in computer graphics is called hsv, which has the following three components:
- The hue, which corresponds directly to the perceived color, such as “red” or “green”.
- The saturation, which is the purity of the color. In other words, how much energy is coming from wavelengths other than the wavelength of the hue?
- The value, which corresponds to the brightness.
Fill the gap
_ in the ganglion layer and LGN detect simple features
in different spots in the retinal image.
HSV is an abbreviation for: (write right css selector for div that contains correct answer)
Most popular color spaces/models.
HSV
RGB
Drag the label into the correct column.
Colors displays use to simulate the entire spectral power distribution of light
Colors displays don't use to simulate the entire spectral power distribution of light
red
green
purple
black
blue
yellow
Dimensionality reduction
Light energy is a jumble of wavelengths and magnitudes that form the spectral power distribution. As the light passes through our eyes and is focused onto the retina, each photoreceptor receives a jumble of light energy that contains many wavelengths. Our limited hardware cannot possibly sense the entire function. Instead, the rod and cone photoreceptors sample it with a bias toward certain target wavelengths. The result is a well-studied principle in engineering called dimensionality reduction.
True/False question
Perception of distance is related to the distance of objects from our eyes,
which is also related to the perception of object scale.
Implement a function that prints right answer to the question:
What collects enough photons to cause the image to be perceived?
Sort the answers to match the definitions.
Saccadic suppression and prioception are related to _ .
Persistence of vision theory states that images persist in the
vision system during the intervals in between frames, thereby causing them to be perceived as _ .
perception of motion
continuous
Highlight the key terms in the definitions below:
A measure of how many individual frames are displayed or processed per second.
Refers to the physical size of the image of an object as it is projected onto the retina.
The conclusion that can be drawn from something although it is not explicitly stated.
Fill the gap
What is the body’s ability to estimate its own motions due to motor commands,
which includes the use of eye muscles in the second case.
FPS is an abbreviation for (pick one answer only)
Answer the question
Once how many FPS are reached, the motion is obviously more smooth and we start to lose
the ability to distinguish individual frames?
Perception of depth - examples
