Graphics

Question 1

Which one case below is not a good illustration for application of computer graphics?

A) DALL-E 2 is a new artificial intelligence system that can produce realistic images and art from a description in natural language.
B) Scene depiction in NASA’s Gemini era flight simulators depended on the use of television cameras and fake “spacescapes”. Models or large photographs of the Earth from space provided scenes that were picked up by a television camera on a moving mount. Signals from the computers moved the camera, thus changing the scene
visible from the spacecraft “windows,” actually monitors.

C) Some animation for the first Star Wars film was created by Larry Cuba in the 1970s at the Electronic Visualization Laboratory (EVL) of the University of Illinois at Chicago. This included a rotating blueprint of the Death Star space battle station produced on a vector monitor connected to a PDP-11/45 computer.

D) Pixar uses its proprietary photorealistic 3D rendering software RenderMan to produce their in-house 3D animated movies.

Answer 1

B)

Question 2

Three independent fundamental elements of image formation are usually considered to be: _____, visible spectrum of which excites receptors in human visual system; _____, which exists in space and can be synthetic as well, and _____, which is someone or something that provides means of forming images from the former. Note: Please submit
your answers as singular nouns.

Answer 2

light, object, viewer

Question 3

Virtually in all modern graphics systems the image we see on the output device is an array of smallest picture elements produced by this system, each called a(n) _____. Collectively this array, called the _____, is stored in a part of memory called the _______.

Answer 3

pixel, raster, framebuffer

Question 4

How many colors can be displayed in a graphical system with a 16-bit-deep framebuffer?

Answer 4

2^16

Question 5

The main principle of three-color theory is that if two colors produce the same tristimulus values (responses of the three types of cone receptor cells), then they are visually indistinguishable. Hence a display needs to vary the intensity of only three primary colors to produce a needed color for a human observer. While ________ color models are used where an initially black display is lightened up by primary colors, ________ color models are used, for example, in printing or painting where colored pigments remove color components from light that is striking the surface.

Answer 5

additive, subtractive

Question 6

In a most popular additive color model named RGB the acronym stands for _______.
A) red-green-blue model
B) Rosencrantz-Guildenstern-Brahe model
C) randomly generated beams model
D) raster graphics binary model

Answer 6

A)

Question 7

A _______ ________ is a simple example of optical imaging systems that helps to compute the image using equations of simple perspective. It led directly to the conceptual foundation for modern three-dimensional computer graphics. The paradigm known as _________-_________ model is the basis for a number of popular APls, including OpenGL and Direct3D. It is similar to the previous model, but avoids the issue of flipped image of the object by introducing the projection plane.

Answer 7

pinhole camera,
synthetic-camera

Question 8

What is the main advantage of the original Bresenham’s line drawing algorithm over the standard DDA (digital differential analyzer) algorithm?
A) It helps with drawing lines of different thickness.
B) It helps with drawing lines appearing smoother on the screen.
C) It helps with drawing lines using different colors.
D) It helps with drawing lines using integer operations.

Answer 8

D)

Question 9

Considering image formation as a two-step process first became important in computer-aided design and animation where, due to the limitations of the hardware the first step named _______ (which is about developing a mathematical coordinate-based representation of any object by defining edges, vertices, and polygons) needed to be separated from the second step named ________ (that is the process of generating an image by means of a computer program).

Answer 9

modeling, rendering

Question 10

Which of the following formulas is most relevant for modeling surface of a cylinder with radius r and height h, oriented along the z-axis and centered at the origin of the coordinate system as shown on the scheme below?
A) x= rcosa, y = rsina, z = hsina (0 ≤ a ≤ 2pi)
B) x= rcosa, y = rsina (0 ≤ a ≤ 2pi), 0 ≤ 2 ≤ h
C) x = rcosa sinß, y = r*cosa cosß, z = € [0. h] (0 ≤ aB ≤ 2pi)
D) x= rcosa sinß, y = r cosa cosß, z = r sina (0 ≤ aB ≤ 2pi)

Answer 10

B)

Question 11

HTMLS ______ element represents an immediate mode bitmapped area of the screen that can be manipulated with JavaScript. The basic API includes also the ____ context that allows a programmer to draw various shapes, render text, and display images directly onto a defined area of the browser window.

Answer 11

canvas, 2D

Question 12

If the following HTML code shows “hello, world!” on the web page, it means that ___________
‹canvas id-“my-canvas”>hello, world!</canvas>
A) the browser supports the HTMLS canvas clement.
B) the browser supports javaScript and it is not disabled.
C) programmers cannot imagine anything better since Brian Kernigan in 1978
D) the browser does not support the HTMLS canvas element or lavaScript is disabled.

Answer 12

D)

Question 13

Your RGB monitor has got a defective cable so that the R, G, and B outputs from the computer are respectively attached to the G, R, and B inputs on the monitor. When one attempts to display the following colors, what colors will actually appear on the screen? Red will appear as ______, yellow as _______, and white as ________. Note: Do not use abbreviations.

Answer 13

green, yellow, white

Question 14

You write a program to read and process TGA image files. One of the 8-bit fields in the file header is called Pixel Depth. Which one statement below about it is not correct?
A) The value stored in this field correlates with the size of the file in bytes.
B) Common values stored in this field are 8, 16, 24 and 32.
C) This field defines the number of different colors that can be used in the image.
D) This field indicates the number of alpha channel bits per pixel.

Answer 14

D)

Question 15

What will be the size of the image data in bytes for a raster image with the following specifications?
Image width: 800, image height: 480, pixel depth: 24

Answer 15

800400(24/8) = 1152000

Question 16

You have got access to the image data through a data array of bytes, where each pixel is represented by three one-byte values - red, green, and blue, in that order. You can manipulate these values to implement various image filters. Which pseudo-code below best matches turning a full-color image into a greyscale one?

A) data (i] = data[i] ? 127 : 0;
data[i+1] = data[i+1] ? 127: 0;
data[i+2] = data[i+2] ? 127: 0;

B) a = (data[i] + data[i+1] + data[i+2])
/ 3;
data[i] = a; data[i+1] = a; data[i+2] = a;

C) data[i] = 255 - data[i] ;
data[i+1] = 255 - data[i+1]:
data[i+2] = 255 - data[i+2] ;

D) data[i] = data[i] ;
data[i+1] = 0; data[i+2] = 0;

Answer 16

B)

Question 17

Indexed color provides a solution that allows displaying a wide range or colors as tong as the application does not need more colors than could be referenced by a pixel. When an image is encoded in this way, color informaton is not directly carried by the image pixel data, but is stored in a separate array of color specifications called a color lookup table, _______ ______ or palette. Every element in this array represents a color, indexed by its position within the array. Each image pixel does not contain the full specification of its color, but only its index in the palette.

Answer 17

color map

Question 18

You are learning the GIF89a specification to develop a module to process GIF image files. Right after the 6-byte Header comes the 7-byte Logical Screen Descriptor. Several fields are packed into the fifth byte of this descriptor as per the scheme below:

+——————+——————-+———–+———————–+
| Global Color | Color Resolution | Sort Flag | Size of Global |
| Table Flag | | | Color Table |
+——————+——————-+———–+———————–+
| Bit 7 | Bits 6-5-4 | Bit 3 | Bits 2-1-0 |
+——————+——————-+———–+———————–+
If the Global Color Table Flag is set to 1, the value in the 3 least significant bits (0-2) of the byte is used to calculate the number of bytes contained in the Global Color Table. You want to get this size value from the given one-byte value of the packedfield variable. Which operation does not match this goal?

A) size = packedfield % 8, where % is division remainder operation
B) size = packedfield &laquo_space;5&raquo_space; 5, where &laquo_space;and&raquo_space; are bitwise left and right shift operations respectively
C) size = packedfield & 0x07, where & is bitwise AND operation
D) size = packedfield / (2**3), where ** is exponentiation operation

Answer 18

D)

Question 19

There are two fundamental rendering strategies. The _______-oriented approaches, for example ray casting, loop over each pixel, working backward, trying to determine which geometric primitives can contribute to its color, while in the _______-oriented approach, for example in a pipeline renderer, vertices are defined by the program and flow through a sequence of modules that transforms them, colors them, and deter mines whether they are visible.

Answer 19

image, object

Question 20

Which one statement below about ray tracing is generally not correct?

A) Ray tracing uses shadow rays from the point of intersection on the surface to each light source, and if i intersects a surface before meeting the source, the light is blocked and this point is in shadow, at least from this source
B) Ray tracing considers only those rays that start at the center of projection and go through pixel-sized areas on the image plane, since we know that these cast rays must contribute to the image.
C) Each cast ray that starts at the center of projection and goes through pixel sized areas on the image plane intersects either a surface or goes off to infinity without striking anything.
D) A simple form of ray tracing, also referred to as ray casting, colors a pixel with the shade of the polygon at the point of intersection with the cast ray closest to the center of projection.

Answer 20

C)

Question 21

The names of the four major steps in the imaging process depicted in the scheme of the geometric pipeline below are:
1. _______ processor
2. _______ and primitive assembler
3. ________
4. ________ processor

Answer 21

vertex, clipper, rasterizer, fragment

Question 22

Which one statement below about simple perspective projection in synthetic-camera model is generally not correct?

A) Under simple perspective projection, straight lines of objects appear as straight lines on the projection plane.
B) Under simple perspective projection, objects farther from the center of projection appear smaller.
C) In synthetic-camera model, we find the image of a point on the object by drawing a line from that point to the center of projection.
D) In synthetic-camera model, the image of the object appear flipped relative to the object.

Answer 22

D)

Question 23

In the first block of the geometric pipeline, each ______ is processed independently. Much of the work in the pipeline is in converting object representations from one ________ system to another. Imaging systems usually have limited field of view. The equivalent property is considered as a(n) ________ volume, such that the projections of objects within it appear in the image, those that are outside do not. Next, the output of the rasterizer is a set of “potential pixels” for every primitive, each called a(n) _______

Answer 23

vertex, coordinate, clipping, fragment

Question 24

You have got access to the geometrical model data, where each vertex is represented by three x, y and z values. You can loop through all vertices and manipulate these values to implement various transformations. Which pseudo-code below best matches moving the model perpendicular to z-axis?

A) x = x;
y = y
z = z * dz;
B) x = x + dx;
y =y+dy;
z = z;
C) x = x;
y = y;
z = z + dz;
D) x = x * dz;
y = y * dz:
z = z * dz;

Answer 24

B)

Question 25

In a 3-dimensional vector space, we can represent any vector v uniquely in terms of any 3 linearly independent vectors vi, V2, and V3, collectively known as _______: v = a1V + a2V2 + A3V3. However, for
representing points, entities that have fixed positions, a more general method is needed. An alternative representation introduces also the reference point, the origin, which together with the aforementioned 3 vectors determine a(n) _______.

Answer 25

basis, frame

Question 26

Which one statement below is not correct?
For two vectors a = a1v1 + a2v2 + a3v3 and b = B1v1 + B2v2 + B3v3 in the 3-dimensional Euclidian space…

A) …the cross product of a and bis a vector, which is orthogonal (or perpendicular) to both a and b when they are not parallel.
B) …the dot product of a and b is a scalar (or real number), which equals to zero when a and b are orthogonal (or perpendicular).
C) ….the dot product of a and b cannot be used to calculate the sine of the angle between a and b.
D) ..the cross product of a and b has a magnitude equal to the positive area of the parallelogram having a and b as sides

Answer 26

C)

Question 27

All ___________ transformations, known for preserving lines, can be represented as matrix multiplications in ____________ coordinates that use a four-dimensional representation for both points and vectors in three dimensions.

Answer 27

affine, homogeneous

Question 28

Which one statement below about [x y z w] homogeneous coordinates and representation is correct?

A) Homogeneous coordinates are only used to represent affine transformations.
B) Less arithmetic work is involved when using 4-dimensional homogeneous representation to solve 3-dimensional problems.
C) This approach cannot avoid the confusion of having the same coordinates representing both a point and a vector.
D) The fourth coordinate w- for the homogeneous representation of points, while for vectors it is not.

Answer 28

B)

Question 29

You apply two transformations to the vertex v = (3 2 6)^T: first rotating around y-axis by 90 degrees, then uniformly scaling by factor of 2 with a fixed point at the origin. What will be the value of the r
coordinate for the transformed vertex?

Answer 29

12

Question 30

You want to rotate the cube by angle o parallelly to the x-y plane around its center by using available T(d) translation by d and R,(0) rotation around z-axis by e matrices (P, is the vector from origin to the center of the cube). What is the correct way for finding a new vertex v’ for every given original vertex v?

A) 𝑣′ = 𝑇(𝑃𝑓) 𝑅𝑧(𝜃) 𝑇(−𝑃𝑓)𝑣
B) 𝑣′ = 𝑣𝑇(−𝑃𝑓) 𝑅𝑧(𝜃) 𝑇(𝑃𝑓)
C) 𝑣′ = 𝑇(−𝑃𝑓) 𝑇(𝑃𝑓) 𝑅𝑧(𝜃)𝑣
D) 𝑣′ = 𝑇(−𝑃𝑓) 𝑅𝑧(𝜃) 𝑇(𝑃𝑓)𝑣

Answer 30

A)

Question 31

From the perspective of the graphics pipeline, all faces of geometrical objects in the rendered scene are specified. Hense the graphics system must decide which surfaces it displays. It may use algorithms that remove those faces that should not be visible to the viewer, called ______-_______-________ algorithms. These algorithms can be divided into two classes: ________-space algorithms attempt to order the surfaces in the scene such that rendering them in this order provides the correct image. In contrast, _______-space algorithms work as part of the projection process and attempt to determine the relationship among object points that contribute to the same pixel in the final image.

Answer 31

hidden-surface-removal, object, image

Question 32

Which one statement below about z-buffer algorithm is most correct?

A) It determines which polygon eventually contributes to the color of each pixel.
B) It is widely used for correcting vertex coordinates.
C) It determines minimum and maximum z-values to simulate complex landscapes.
D) It is widely used with framebuffers to speed-up the rendering process.

Answer 32

A)

Question 33

The process, called _______ can be used to improve the performance by reducing the number of polygons that pass through all stages of the pipeline, based on their orientation relative to the viewer. A simple implementation would check the angle between the _______ of the polygon and the vector that points at the viewer.

Answer 33

culling, normal

Question 34

Eliminating all back-facing polygons can be done by checking the angle 0 between the polygon normal n and the viewer. Which one statement below about such a test is not correct?

A) The polygon is not back-facing if cos 0 ≥ 0.
B) The polygon is not back-facing if -90 ≤ 0≤90.
C) The polygon is back-facing if 0 < -90 or 0 > 90
D) the polygon is back-facing if the dot product n*v ≥ 0

Answer 34

D)

Question 35

Eagesspagenggsspeeases when we attempt to go trom the contnuous representation of an
object, which has infinite resolution, to a sampled approximation, which has limited resolution. The name _______ has been given to this defect because a similar term in digital signal processing. For example, Bresenham algorithm can be extended it our display supports more than two colors) by using technique known as ________ by __________ _________, which colors each pixel using the percentage of the ideal line that crosses it

Answer 35

aliasing, antialiasing, area, averaging

Question 36

One of the methods for rasterizing a polygon is called flood fill. Suppose that we have only two colors: a background color and a foreground color. With screen coordinates of polygon vertices given, we can use the foreground color to rasterize its edges, for example, using Bresenham’s algorithm. This will result in an unfilled polygon. Given an initial point
(𝑥,𝑦) inside the polygon, we can color all pixels inside with the foreground color.

function floodFill(x, y) {
if (readPixel(x, y) == BACKGROUND_COLOR) {
// Missing lines
}
}

Let’s assume that there is a function readPixel, which returns the color of a pixel, and a function writePixel, which sets the color of a pixel. Which pseudo-code below best matches the missing line(s) of an effective recursive implementation of the flood fill algorithm?

A) writePixel(x, y, FOREGROUND_COLOR);
floodFill(x, y);

B) writePixel(x-1, y, FOREGROUND_COLOR); floodFill(x-1, y);
writePixel(x+1, y, FOREGROUND_COLOR); floodFill(x+1, y);
writePixel(x, y-1, FOREGROUND_COLOR); floodFill(x, y-1);
writePixel(x, y+1, FOREGROUND_COLOR); floodFill(x, y+1);
C) writePixel(x, y, FOREGROUND_COLOR);
floodFill(x-1, y+1); floodFill(x+1, y-1);
floodFill(x-1, y-1); floodFill(x+1, y+1);
D) writePixel(x, y, FOREGROUND_COLOR);
floodFill(x-1, y); floodFill(x+1, y);
floodFill(x, y-1); floodFill(x, y+1);

Answer 36

D)

Question 37

You are given a triangle defined through its three vertices p0 = (0, 0, 0, 1), p1 = (0, 5, -2, 1) and p2 = (2, 0, 2, 1) in a counterclockwise order. Calculate the y-component of the normal vector (not-normalized) of this triangle. Note that right-hand rule determines outward face.

Answer 37

-4

Question 38

Which one statement below about perfectly diffuse reflectors is not correct?
A) Such rough surfaces also called Lambertian surfaces.
B) Such surfaces appear the same to all viewers that face it
C) Amount of light reflected by such surfaces can be estimated by cosine of the angle between the normal and the direction of the viewer.
D) Amount of light reflected by such surfaces is proportional to the vertical component of the incoming light

Answer 38

C)

Question 39

The Phong reflection model supports three types of material-light interactions - ______, which is characteristic of surfaces that scatter the reflected light in all directions, ________, which is seen with surfaces that scatter most of the light in a narrow range of angles, and ________, which considers the effects of the uniform light level in the environment.

Answer 39

diffuse, specular, ambient

Question 40

Which one statement about the following simplified description of the Phong model is not correct?
I = kd Ld I n+ks Ls (vr)^a + ka La
A) It does not consider the cases when dot products become negative, for example when the light source is below the horizon.
B) It does not consider the attenuation as the light travels a distance from the source to the surface.
C) It does not explicitly show that the light sources are described using three-component intensity function.
D) It does not consider the material property that defines how smooth a surface is or how prominent its specular highlight is.

Answer 40

D)

Question 41

Modified Phong reflection model, also known as _______-Phong model, by the last names of its authors, replaces perfect _________ vector and view vector with normal vector and _________ vector in dot product calculations for the specular component.

Answer 41

Blinn, reflection, halfway

Question 42

Which one statement below about the modified Phong reflection model is not accurate?

A) Using it improves the performance by eliminating the need to recalculate reflection vector at every point on the surface.
B) For specular reflection calculations, it uses cosine of an angle twice smaller than in the original model.
C) Using it does not require any changes in the material property coefficients.
D) It is also known as the Blinn-Phong model.

Answer 42

C)

Question 43

The normal vector at a point on a smooth surface can be found by calculating the _______ _______ of two vectors _______ to the surface at that point.

Answer 43

cross product, tangent

Question 44

In perspective projection, the _______ of ________ of the camera is the angle made by the largest object that it can image on its film plane. If the projection plane (or rather the clipping window) is rectangular, rather than square, then this parameter is different for the top and side views. The _______ _________ parameter, which is equal to the _________ of the projection plane divided to its __________, helps with these situations.

Answer 44

field, view, aspect, ratio, width, height

Question 45

When texture coordinates are mapped to the array of texels, it rarely gives a point that corresponds to the center of a texel. One option, called _______ _________, is to use the value of the texel that is closest to the texture coordinate output by the rasterizer. Another strategy that requires more work, known as _______ ________, is to use a weighted average of a group of texels in the neighborhood of the texel determined by the former method.

Answer 45

nearest, sampling, bilinear, filtering

Question 46

The main principle behind Gouraud shading is to define each vertex ________ as the normalized ________ of the normals of every ________ that share this vertex. It is subsequently used in calculations of the vertex color by application of the ________- _______ reflection model.

Answer 46

normal, average, face, Blinn, Phong

Question 47

Data is to be transferred from the CPU to variables in the shader. In a given application, a variable may change in a variety of ways, as indicated by use of storage qualifiers. For example, we may want parameters that will remain the same for all vertices that are displayed. Such variables that are constant throughout the pipeline are called ________ qualified variables. In contrast, when we send vertex positions to a shader, for example, they can be different for each vertex in a primitive. Such per-vertex variables are indicated by the qualifier _________, which is valid only inside the vertex shader. Finally, ________ qualified per-fragment variables create link between a vertex shader and a fragment shader for interpolated data.

Answer 47

uniform, in, out