Cartes mémoires Interaktive Computergrafik (Seite 2 von 5)

Cartes-fiches	194
Langue	Deutsch
Catégorie	Informatique
Niveau	Université
Crée / Actualisé	24.04.2021 / 21.07.2021
Lien de web	https://card2brain.ch/box/20210424_interaktive_computergrafik
Intégrer	<iframe src="https://card2brain.ch/box/20210424_interaktive_computergrafik/embed" width="780" height="150" scrolling="no" frameborder="0"></iframe>

Why is the CMYK color model often used in favour of the CMY color model?

Printers may not be able to properly mix cyan magenta and yellow to produce black and instead use black ink directly.

The CMYK color representation is more prone to rounding errors than the CMYK representation.

The CMYK color model can describe a wider gamut than the CMY color model.

Why was the YUV color model developed?

To be more intuitive for artists drawing a digital painting

To describe the whole human perceivable colors.

To describe color information for early TV sets.

How does the color model described by the HSV model look?

cube

cone

double cone

How does the color model described by the HSL model look?

cube

cone

double cone

What aspect does the H dimension of the HSV color model control?

The color’s tone.

The saturation.

The brightness.

The perception intensity.

What advantages has the HSV color model have?

It is more intuitive.

It can be displayed on more devices than the RGB color model.

It carries more color information than the CMY color model.

Asking small children, what the number halfway in between 1 and 9 is, often results in the answer of 3 instead of 5. Why is that the case?

Smaller numbers are more familiar at young age and larger numbers therefore seem to be further away.

The number is in half way in between on the logarithmic scale

Steven’s Power Law

The Uncertainty Principle

Most visual sensors and displays have a characteristic nonlinear relationship of input and output signal levels. How can we compensate for this distortion?

Use Gamma correction.

It is not possible, because we would need to have the relationships of all devices.

Find the inverse function of the distortion and apply it to the signal.

Increase / Decrease the brightness by multiplying with a factor.

Which postulation describes the connection between a stimulus’ intensity and the perceived intensity?

Stephen’s Power Law

Exponential Stimulus Law

Stelato’s Increase Law

Weber-Fechner Law

How does a stimulus’ intensity and the perceived intensity relate to one another?

differential relationship

nonlinear relationship

oscillating relationship

The eye is more sensitive for ...... areas than for ...... areas. The eye ....... discontinuities of brightness.

....darker...

...brighter...

..accentuates...

What is the result of floor(1.65) ?

1

1.5

1.6

2

An intensity of 1 is mapped onto an 8 bit number with gamme=0.3. Which value is assigned to the number?

0

1

256

76

255

The definition of picture elements (or pixels for short) given does not match the structure and principles of human vision and the eyes on a fundamental level. What are reasons for this mismatch?

Different geometry of displays and visual fields.

No homogeneous distribution of receptors

Cone cells have no primary color.

Specialized cells not for image formation but for movement.

There is no single framerate in nature.

The graphics card is sending pixel information to the screen for every frame to be rendered. Let us assume a display resolution of 1920 (h) x 1080 (v) with a fixed refresh rate of 60 Hz, 8 bits per pixel primary color channel, three channels, and no compression. How much net bandwidth do the components have to provide.

100 Mbit/s

1,43 Gbit/s

2,85 Gbit/s

9.001 Gbit/s

Identify the situations, where it seems advisable to choose a graphics type over the other. Remember limitations for the situations. Vector or Raster?

situations: text, logo design, user interface objects, CAD modeling, omage manipulations, sensory input, display output

Vector: text, logo design, user interface objects, CAD modeling

Raster: omage manipulations, sensory input, display output

Assign common image formats to the way their information is primarily described. Vector or Raster Format

formats: Postscript, PNG, TIFF, JEPG; GIF, SVG

Vector Format: Postscript, SVG

Raster Format: PNG, TIFF, JPG

Which image descriptions are resolution independent?

scanned art

text

bélèr curves

polygons

How can color be described by a limited amount of bits?

By indicating values of a particular color model.

By entangling quants with the appropriate natural occurrence

By using a pointer into a color table.

By describing a factor on top of a predefined value

Which amount of bits are typically used for which color model coding?

black and white, true color, 256 colors from color table

1 bit: black and white image

8 bits: 256 colors out of a color table

24 bits: True Color, 256 shades for each primary color

What is aliasing?

An effect that causes different signals to become indistinguishable.

A rasterization approach for smooth lines.

A sampling method to reconstruct the original, continuous signal

What types of aliasing exist?

Spacious Aliasing.

Continuous Aliasing

Temporal Aliasing

Random Aliasing.

What is true of the Supersampling approach?

Supersampling uses multiple samples per pixel.

Supersampling uses multiple pixels per sample.

Supersampling averages colors

Supersampling maximizes colors.

What is true of grid sampling?

Grid sampling samples in regular intervals.

Grid sampling avoids moiré patterns.

Grid sampling amplifies grids

Grid sampling prevents aliasing

What is true of stochastic sampling?

Stochastic sampling samples at random points.

Stochastic sampling samples every pixel uniformly.

Stochastic sampling produces coarse grained images.

Stochastic sampling substitutes aliasing with noise

What is true of stratified sampling?

Stratified sampling produces less noise than grid sampling

Stratified sampling samples in homogenous subgroups.

Stratified sampling maximizes the variance in random selection.

Nyquist-Shannon Theorem and Audiophiles

Audiophiles do love analog and lossless digital records. The most prominent argument is recognizable sound quality manifesting itself in less noise. Under which circumstances is the Nyquist-Shannon Theorem contradicting better sound quality and renders the lossy compressions like MP3 a competitive alternative.

Data is sampled with 48kHz

There are no frequencies in the scene to be recorded higher than the sampling rate allows

At the time of recording, higher frequencies than the theorem allows are cut off by a filter.

Data is sampled with 128kHz.

Nyquist-Shannon Theorem and Video-/Audiophiles

What can a recorder do before recording to diminish aliasing within audio and visual data

Nothing, there will always be noise when using digital sampling.

Using a high enough sampling frequency so that the artifacts are not as prominent

Averaging over the sampled data.

Avoid high frequencies by compatible countermeasures in the setup

What is true for Photo Realism?

Photo Realism is a property of an image.

Photo realistic images can be generated by women.

Photo realism necessitates the use of a physical camera

Photo realism can describe the production of a sculpture.

How can light interact with objects?

It gets absorbed and disappears.

It refracts by passing through the surface.

It bounces and cintinues on a curved path.

Which are physical models for light?

The proton description

The back propagation.

The particle view.

What is true for Photons in the Photon-based Light Propagation Model?

Photons are eventually completely absorbed.

Every photon passes the pupil to reach the retina

Photons may create stimulus responses

When creating an image with photon forward propagation…

you will have to create many photons

many photons will reach the camera.

you need to simulate photon-material interactions

the computing power is used efficiently

Photon backward propagation …

only considers photons which hit the camera

follows photon paths from source

has a variant known as photon mapping

simulates a global light transport.

Which are requirements for raytracing?

Photons

Camera (description/model)

Scene description

Scene graph

Which kind of algorithms are required for raytracing?

Calculation of closest intersection between ray and scene

Assessment of similarities between spheres and the image canvas

Determination of incoming Radiance at point of intersection

Processing of curvature of photon rays

Which order of pseudo code instructions is necessary for the raytracing algorithm?

camera.generateRay image.set shade scene.intersect

camera.generateRay scene.intersect shade image.set

shade scene.intersect image.set camera.generateRay

What is true of a ray starting at point x0 that runs in direction d ?

Its parametric form is: x(t)=d+tx0

It is defined as a half line.

The parameter t of the parametric form is of range t in [0,1]

How many intersections can there be when testing ray-sphere intersections?

0

1

2

3

In which case are there no intersections of a plane defined by n*x-d=0 and a ray defined as x(t)=x₀+td?

n*d=0

n*d=1

n*(x0+td)-d=0

Interaktive Computergrafik

Créer ou copier des fichiers d'apprentissage

Créer ou copier des fichiers d'apprentissage

Connecte-toi pour voir toutes les cartes.

SWITCHaai

Office 365

Edulog

Apple ID

Google