Category: Computer Graphics Objective Questions

Computer Graphics Multiple Choice Questions & Answers (MCQs) on “Two Dimensional Viewing”.

1. A view is selected by specifying a sub-area of the __________ picture area.
a) half
b) total
c) full
d) quarter

Answer: b
Clarification: We consider a formal mechanism of view, that is, which part of the picture is to be displayed. That’s why we select a view by specifying a sub-area of the total picture area.

2. Co-ordinates are ranging according to the screen resolution.
a) True
b) False

Answer: a
Clarification: When we display a scene, only those objects which have a particular window are displayed. So for that mechanism to work, co-ordinates are made to range themselves according to the screen resolution.

3. Any convenient co-ordinate system or Cartesian co-ordinates which can be used to define the picture is called ___________
a) spherical co-ordinates
b) vector co-ordinates
c) viewport co-ordinates
d) world co-ordinates

Answer: d
Clarification: World Coordinate Systems (WCS) are the type of coordinate systems which describe the physical coordinates associated with a data array, such as sky coordinates. It is also used to denote wavelengths of a spectrum and to draw astronomical images.

4. Which of the following co-ordinates are NOT used in 2d viewing transformation?
a) modelling co-ordinates
b) viewing co-ordinates
c) vector co-ordinates
d) device co-ordinates

Answer: c
Clarification: Vector co-ordinates are used to denote vectors which are physical quantities having magnitude as well as direction. In 2d viewing transformations- Modelling co-ordinates, viewing co-ordinates, Normalised co-ordinates and Device co-ordinates are used.

5. The process of elimination of parts of a scene outside a window or a viewport is called _____________
a) cutting
b) plucking
c) clipping
d) editing

Answer: c
Clarification: Clipping is the process of cutting out extra material. In the context of computer graphics, clipping is a method to selectively enable or disable rendering operations within a defined region of interest.

6. For a 2d transformation viewing, in how many ways a clipping algorithm can be applied?
a) 3
b) 2
c) 1
d) 5

Answer: b
Clarification: Clipping algorithm can be applied in two ways for 2d transformation viewing. Two ways in which clipping algorithms can be applied are- 1) world co-ordinate clipping. 2) viewport clipping.

7. Which of the following is NOT a type of clipping algorithm used on the raster system?
a) line clipping
b) point clipping
c) area clipping
d) solid clipping

Answer: d
Clarification: Since clipping is done in 2 dimensional viewing and solid is a 3 dimensional object so clipping algorithm can’t be applied on a solid object. Instead of solid clipping, there is another type of clipping algorithm known as curve clipping.

8. For a point to be clipped, which of the following conditions must be satisfied by the point?
a) xw_min < x < xw_max
b) xw_min = x = xw_max
c) xw_min > x > xw_max
d) yw_min = y = yw_max

Answer: c
Clarification: A point P(x,y) is NOT clipped if x is more than the minimum value of x and less than the maximum value of x. Mathematically, it can be written as “xwmin ≤ x ≤ xw_max“.

9. For a point to be clipped, which of the following conditions must be satisfied by the point?
a) yw_min < y < yw_max
b) yw_min > y > yw_max
c) yw_min = y = yw_max
d) xw_min < x < xw_max

Answer: b
Clarification: A point P(x,y) is NOT clipped if y is more than the minimum value of y and less than the maximum value of y. Mathematically, it can be written as “yw_min ≤ y ≤ yw_max“.

10. Which type of clipping is used to clip character strings?
a) text clipping
b) line clipping
c) sentence clipping
d) word clipping

Answer: a
Clarification: Text clipping is the algorithm which is used to clip character strings. It depends on the methods which are used to generate original characters.

11. In polygon clipping, line clipping algorithms can be used.
a) True
b) False

Answer: a
Clarification: Polygon is a two dimensional shape formed by straight lines. So we can conclude, polygon’s basic components are lines, hence line clipping algorithm can be used for polygon clipping.

Computer Graphics multiple choice questions on Line Attributes.

1. The basic attributes of a straight line segment are
a) Type
b) Width
c) Color
d) All of these

Answer: d
Clarification: Type, width and colors are the basic attributes of line.

2. A dashed line could be displayed by generating_________.
a) Inter dash spacing
b) Very short dashes
c) Botha a and b
d) A or B

Answer: a
Clarification: The inter dash spacing that is equal to the length of the solid sections displays dashed line.

3. A dotted line can be displayed by generating
a) Very short dashes with spacing equal to and greater than dash size
b) Very long dashes with spacing equal to or greater than dash size
c) Very short dashes with spacing equal to and greater than dash size
d) Dots

Answer: c
Clarification: Very long dashes with spacing equal to or greater than dash size can displays dotted line.

4. Which of the following is not a line-type?
a) Dashed line
b) Dark line
c) Dotted line
d) Only b

Answer: d
Clarification: Except dark line those are the types of the line.

5. In an application program, to set line-type attributes the following statement is used.
a) SetLinetype(lt)
b) setLinetype(lt)
c) SETLINETYPE(lt)
d) SETLINE()

Answer: b
Clarification: None.

6. The algorithm which displays line-type attributes by plotting pixel spans is
a) Raster line algorithm
b) Raster scan algorithm
c) Random line algorithm
d) Random scan algorithm

Answer: a
Clarification: Raster line algorithm displays line-type attributes.

7. Pixel mask means
a) A string containing only 1;s
b) A string containing only 0’s
c) A string containing 1 and 0
d) A string containing 0 and 0

Answer: c
Clarification: Inter span spacing can be specified in a pixel mask that contains digits 1 and 0.

8. A heavy line on a video monitor could be displayed as
a) Adjacent perpendicular lines
b) Adjacent parallel lines
c) Both a and b
d) Neither a nor b

Answer: b
Clarification: A heavy line displayed as adjacent parallel lines, while pen plotter might require pen changes.

9. To set the line-width attribute the following command is used.
a) SETLINEWIDTHSCALEFACTOR (lw)
b) Setlinewidth()
c) Setlinewidthscalefacto (lw)
d) setLineWidthScaleFactor (lw)

Answer: d
Clarification: setLineWidthScaleFactor (lw) function can be used to set line-width attribute.

10. The parameter to “setLineWidthScaleFactor (lw) “function specifies?
a) Standard width
b) Relative width of the line
c) Thickness of the line
d) All of the mentioned

Answer: b
Clarification: The positive value to lw indicates the relative width of the line.
Standard width, if Value=1
Thickness, if value>1.

11. We can adjust the shape of the line ends to give them a better appearance by using
a) Line spacing
b) More dots
c) Line caps
d) Round cap

Answer: c
Clarification: Line caps are obtained by adjusting the end points of the line.

12. Thick line drawn with
a) Butt caps
b) Round caps
c) Projecting square caps
d) All of the mentioned

Answer: d
Clarification: None.

13. We set the line-color value in PHIGS with the function
a) setPolylineColorIndex (lc)
b) setline Color()
c) SETPOLYLINECOLORINDEX (lc)
d) Only b

Answer: a
Clarification: The setPolylineColorIndex (lc) function is used to set the line color.

14. If the angle between 2 connected line segments is very small then ________ can generate a long spike that distorts the appearance of the polyline.
a) Miter join
b) Round join
c) Bevel join
d) None of the mentioned

Answer: a
Clarification: Miter join provides long spikes that distort the appearance of the polyline.

15. A line drawn in the background color is
a) Visible
b) Invisible
c) Visible or Invisible
d) Only b

Answer: d
Clarification: A line drawn in the background color is always invisible because both are same color.

Computer Graphics Interview Questions and Answers for freshers on “Window to Viewport Coordinate Transformation”.

1. The object space or the space in which the application model is defined is called ____________
a) World co-ordinate system
b) Screen co-ordinate system
c) World window
d) Interface window

Answer: a
Clarification: World Coordinate System also called as WCS is any coordinate systems that describe the physical coordinates associated with a data array. They also used for an astronomical image, or for determining the wavelength scale for a spectrum.

2. What is the name of the space in which the image is displayed?
a) World co-ordinate system
b) Screen co-ordinate system
c) World window
d) Interface window

Answer: b
Clarification: The coordinate system of the screen is a Cartesian coordinate system. The origin (0,0) is at the top left of the screen. Point is denoted by (x,y), where x is x co-ordinate and y is y co-ordinate.

3. What is the rectangle in the world defining the region that is to be displayed?
a) World co-ordinate system
b) Screen co-ordinate system
c) World window
d) Interface window

Answer: c
Clarification: The world window specifies which part of the window needs to be drawn. It also defines which part of the window should be drawn and which part outside the window should not be drawn and should be clipped away.

4. The window opened on the raster graphics screen in which the image will be displayed is called _____________
a) World co-ordinate system
b) Screen co-ordinate system
c) World window
d) Interface window

Answer: d
Clarification: In common words, it is termed as a Graphic user interface. It allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation.

5. The process of mapping a world window in World Coordinates to the Viewport is called Viewing transformation.
a) True
b) False

Answer: a
Clarification: The viewing transformation is the operation of computer graphics in which the maps are the perspective view of an object in world coordinates into a physical device’s display space.

6. The scale factor of viewport transformation for x co-ordinate is ________
a) S_x = (sv_max – sv_min)/ (sw_max – sw_min)
b) S_x = (sv_max – sv_min)/ (sw_max + sw_min)
c) S_x = (sv_min – sv_max)/ (sw_max – sw_min)
d) S_x = (sv_max + sv_min)/ (sw_max – sw_min)

Answer: a
Clarification: The mapping or transformation involves developing formulas that start with a point in the world window, say (xw, yw). The formula is used to produce a corresponding point in viewport coordinates, say (xv, yv). So after keeping it proportional in ‘x’ co-ordinate, we get, (sv_max– svmin)/ (sw_max – swmin).

7. The scale factor of viewport transformation for x co-ordinate is ________
a) S_y = (sv_max + svmin)/ (sw_max + sw_min)
b) S_y = (sv_max – svmin)/ (sw_max + sw_min)
c) S_y = (sv_max – svmin)/ (sw_max – sw_min)
d) S_y = (sv_max + svmin)/ (sw_max – sw_min)

Answer: c
Clarification: The mapping or transformation involves developing formulas that start with a point in the world window, say (xw, yw). The formula is used to produce a corresponding point in viewport coordinates, say (xv, yv). So after keeping it proportional in ‘y’ co-ordinate, we get, (sv_max – sv_min)/ (sw_max – sw_min).

8. Panning is a technique in which users can change the size of the area to be viewed in order to see more detail or less detail.
a) True
b) False

Answer: b
Clarification: The technique in which users can change the size of the area to be viewed in order to see more detail or less detail is called ‘Zooming’. Panning means sliding the camera.

9. Drawing of number of copies of the same image in rows and columns across the interface window so that they cover the entire window is called ____________
a) Roaming
b) Panning
c) Zooming
d) Tiling

Answer: d
Clarification: Drawing of number of copies of the same image in rows and columns across the interface window so that they cover the entire window is called ‘tilling’. To achieve tiling in computer graphics, the window remains static and the viewport is changed many times.

10. By changing the dimensions of the viewport, the _________ and ___________ of the objects being displayed can be manipulated.
a) Number of pixels and image quality
b) X co-ordinate and Y co-ordinate
c) Size and proportions
d) All of these

Answer: c
Clarification: By changing the dimensions of the viewport, the size and proportions of the objects being displayed can be manipulated, this leads to the zooming effect of the image by successively mapping different dimensioned clipping windows on a fixed sized viewport.

Computer Graphics multiple choice questions on Curve Attributes.

1. The basic parameter to curved attributes are
a) Type
b) Width
c) Color
d) All of the mentioned

Answer: d
Clarification: Type, width and colors are the basic parameters to curved attributes.

2. Raster curves of various widths can be displayed using
a) Horizontal or vertical spans
b) Horizontal spans
c) Vertical spans
d) Horizontal and vertical spans

Answer: a
Clarification: Raster curves of various widths can be displayed using Horizontal or vertical spans.

3. If the magnitude of the curve slope is lesser than 1, then
a) We can plot horizontal spans
b) We can plot vertical spans
c) Only b
d) All of the mentioned

Answer: c
Clarification: if slope magnitude 1 then we can plot vertical spans.

4. If the slope magnitude is 1, then circles, ellipse and other curves will appear
a) Thick
b) Thinnest
c) Big
d) Rough

Answer: b
Clarification: The magnitude value 1 displays thinnest curves, circles and ellipses.

5. One of the method for displaying thick curves is
a) Curve slope
b) Curve width
c) Curve cap
d) Only c

Answer: a
Clarification: This method fills the area b/w 2 parallel curves, whose separation distance=desired width.

6. The pixel masks for implementing line-type options are also used in the following algorithm to generate dashed and dotted patterns.
a) Raster line algorithm
b) Raster scan algorithm
c) Raster curve algorithm
d) Random curve algorithm

Answer: c
Clarification: Raster curve algorithm generates dashed and dotted patterns.

7. We can generate the dashes in the various octants and the circle path with vertical path using
a) Circles
b) Circle symmetry
c) Circle simmetry
d) Curve slope

Answer: b
Clarification: Circle symmetry generates dashes in the various octants, but we must shift the pixel positions to maintain the correct sequence.

8. The function of the pixel mask is
a) To display dashes and inter dash spaces according to the slope
b) To display curved attributes
c) To display the thick curves
d) None of these

Answer: a
Clarification: None.

9. If we want to display constant-length dashes, then we need to do the following.
a) We need to adjust the number of pixels plotted in each dash
b) We need to adjust the number of dots
c) We must use line-type functions
d) Neither a nor c

Answer: a
Clarification: Number of pixels plotted in each dash, will displays constant-length dashes.

10. The curves displayed with a rectangular pen will be
a) Thinner
b) Thicker and magnitude slope is 1
c) Thicker and magnitude slope >1
d) B or C

Answer: b

Computer Graphics Multiple Choice Questions & Answers (MCQs) on “Clipping Operations”.

1. What is the primary use of clipping in computer graphics?
a) adding graphics
b) removing objects and lines
c) zooming
d) copying

Answer: b
Clarification: The primary use of clipping in computer graphics is to remove objects, lines, or line segments that are outside the viewing pane.

2. A polygon can be clipped using clipping operations.
a) True
b) False

Answer: a
Clarification: A polygon can also be clipped by specifying the clipping window. Sutherland Hodgeman polygon clipping algorithm is used for polygon clipping.

3. Which vertex of the polygon is clipped first in polygon clipping?
a) top right
b) bottom right
c) bottom left
d) top left

Answer: d
Clarification: In polygon clipping, first the polygon is clipped against the left edge of the polygon window to get new vertices of the polygon. So, it is the top left which is clipped first.

4. How many methods of text clipping are there?
a) 5
b) 4
c) 3
d) 2

Answer: c
Clarification: There are three methods for text clipping which are −
1) All or none string clipping 2) All or none character clipping 3) Text clipping.

5. A bitmap is collection of ___________________ that describes an image.
a) bits
b) colors
c) algorithms
d) pixels

Answer: d
Clarification: A bitmap is a collection of pixels that describe an image. It is a type of computer graphics that the computer uses to store and display pictures.

6. We can change the size or resize the bitmap image.
a) True
b) False

Answer: b
Clarification: We can’t resize the bitmap image. When the bitmap image is resized, the image pixels get distorted. It is one of the main disadvantages of the bitmap.

7. In line clipping, the portion of line which is _____________ of window is cut and the portion that is _____________ the window is kept.
a) outside, inside
b) inside, outside
c) exact copy, different
d) different, an exact copy

Answer: a
Clarification: Line clipping follows the same algorithm that is in the case of point clipping. So, in line clipping also, we will cut the portion of the line which is outside of the window and keep only the portion that is inside the window.

8. ‘Skala’ is an example of which type of clipping?
a) curve clipping
b) point clipping
c) polygon clipping
d) line clipping

Answer: d
Clarification: Skala is a type of clipping operation which can be used for a line or line-segment clipping against a rectangular window, as well as against a convex polygon. Its algorithm is based on homogenous co-ordinates and duality.

9. ‘Vatti’ clipping algorithm is used in _________________
a) curve clipping
b) point clipping
c) polygon clipping
d) line clipping

Answer: a
Clarification: Vatti is used in polygon clipping. It allows clipping of any number of arbitrarily shaped subject polygons. It can also be used to clip any number of arbitrarily shaped polygons.

10. The process of removal of hidden surfaces is termed as _______________
a) clipping
b) copying
c) culling
d) shorting

Answer: c
Clarification: An area which is related to the visible surface determination (VSD) is called culling. ‘Viewing frustum culling’ and ‘Backface culling’ are examples of some culling algorithms.