RTU Computer Graphics: Important Interview Questions

We have prepared a post for rajasthan technical university, rtu computer graphics syllabus based computer graphics subject interview questions and answer. Which will help to rtu students in any interview and viva.

rtu computer graphics and multimedia


RTU Computer Graphics Interview Questions

A list of frequently asked RTU Computer Graphics Interview Questions and Answers are given below.


1) What is Computer Graphics?

Ans. Computer graphics involves display, manipulation, storage of images, and experimental information for proper visualization.

A computer graphics system consisting of

  • Host computer
  • Processor
  • Memory
  • Frame Buffer
  • Display Device
  • A set of an input device

2.) Write the properties of video display devices?

Ans. Properties of video display methods are Persistence, resolution, and aspect ratio.


3.) Write the essential application of computer-graphic?

Ans. Following is the application of computer graphic

  • Computer graphics is used in the range of computer-aided design.
    It is used to produce illustrations for documents or to generate slides for with projections.
  • The expert uses a combination of 3D modeling methods, texture mapping, drawing programs, and CAD software.
  • In the field of entertainment, CG techniques are now commonly used in making motion pictures. Music videos and television shows.
  • Computer-generated models of physical, financial, and economical methods are used as educational aids.


4) Write the difference between vector and raster graphics?

Ans. Following are the difference between vector and raster graphics:

  • Raster or Bitmap images are resolution-dependent because of this, it's not possible to increase or reduce their size without sacrificing on image quality.
  • While the vector-based display is not dependent on resolution, the range of vector image can be increased or reduced without affecting image quality.
  • Unlike a raster image, a vector picture can't be used for realistic pictures. This is because vector images are made up of solid-color areas and scientific gradients, so they can't be used to demonstrate the continuous tone of colors in a natural photograph.


5.) What are the advantages and disadvantages of direct view storage tubes?


  • Refreshing is not necessarily.
  • Without flicker, very complex images can be exhibit at very high resolution.
  • Refreshing of the screen is not needed.


  • They normally never display color.
  • Selected part of the picture never deleted.
  • It can take quite a few second for composite images while redrawing and eliminating the process.


6.) Define Aspect Ratio?

Ans. Aspect ratio is the ratio of the vertical points to horizontal points essential to produce equivalent length line in both direction on the screen. An aspect ratio of 3/4 defines that a vertical line plotted with three points has the same length as a horizontal lines plotted with four points.


7.) Differentiate between Raster and Vector Graphics?

Raster Graphics Vector Graphics
Raster graphics are consist of pixels Vector graphics are consist of paths
Raster image pixels do not include their appearance as to size increases Vector image do retain appearance regardless of estimate.
Raster graphics are not scalable Vector images are scalable


8.) What are the advantage and disadvantages of DDA Algorithm?


  • It is the most straightforward algorithm.
  • It is a faster process for calculating pixel positions.


  • Floating-point arithmetic in DDA technique is time-consuming.
    Endpoint accuracy is poor.


9.) Difference between DDA and Bresenham's line drawing algorithm.

Basics DDA Algorithm Bresenham's line Algorithms
Arithmetic DDA algorithm uses floating point, i.e., Real Arithmetic's. Bresenhams algorithm uses fixed point, i.e., Integer Arithmetic's.
Operations DDA algorithms uses multiplication and division in its operation. Bresenhams algorithm use only subtraction and addition in its operations.
Speed DDA algorithm is slowly than Bresenham's algorithm inline drawing because it uses real arithmetic (floating-point methods). Bresenhams algorithm is faster than the DDA algorithm inline drawing because it performs only addition and subtractions in its calculation and uses only integer arithmetic, so it runs significantly fast.
Accuracy & Efficiency DDA algorithms is not as accurate and efficient as Bresenham's algorithm. Bresenham's algorithm is much accurate than the DDA algorithms.
Drawing DDA algorithm can draw circle and curves, but which is not as accurate as Bresenhams Bresenhams algorithm can draw circle and curves with much more accuracy than DDA Algorithm.
Expensive DDA algorithm uses an excessive number of floating-point multiplications, so it is costly. Bresenhams algorithm is less costly than the DDA algorithm as it uses only addition and subtraction.


10.) What is Translation?

Ans. A translation is used to an object by repositioning it along a straight line path from one co-ordinate point to another. We translate a 2-D points by adding translation distance, tx, and ty, to the original coordinates position (x,y) to move the points to a new position (x', y').

x' = = x + tx
y' = y + ty.


11.) What is Reflection?

Ans. A Reflection is a transformation which produces a mirror display of an object. The mirror image for a 2D reflection is created relative to an axis of reflection by rotating the objects 180 degrees about the reflection axis.


12.) What is Shearing?

Ans. A transformation which distorts the shape of an object such that the transformed way develop as if the object were consist of internal layers that had been caused to slide over each other is known as shearing.


13.) What is viewing transformation?

Ans. The mapping of a component of a world-coordinate scene to device coordinates is called a viewing transformation.


14.) Define Clipping and Clip window.

Ans. Any method that identifies those portions of a display that are either inside or outside of a particular region of space is referred to as a clipping algorithm or simply clipping. The region against which an object is clipped is known a clip window.


15.) Differentiate between parallel projections from perspective projection.

Parallel Projection Perspective Projection
In parallel projection, coordinate positions are changed to the view plane along parallel lines. In perspective projection, object positions are changed to the view plane along lines that converge to a point known as a projection reference point or center of projection.
Preserves the related proportions of objects. Produce realistic vision but does not keep relative proportions.
It is used in drafting to produce scale drawings of 3Dobjects. Projections of distant objects are lower than the projections of objects of the same size that are near to the projection plane.


16.) What is the need for space partitioning representation?

Ans. Space partitioning representations are used to define interior methods, by partitioning the spatial domain including an object into a set of small non-overlapping, and contiguous solids. A common space partitioning description for a three object is an octree representation.


17.) What is the quadric surfaces?

Ans. Quadric surfaces are described with second-degree equations (quadrics). They include sphere, ellipsoids, tori, paraboloids, and hyperboloids. Spheres and ellipsoids are necessary components of graphic scenes; they are often feasible in graphics packages from which more complex object can be constructed.


18.) What is critical fusion frequency?

Ans. Frequency of light simulation at which it becomes perceived as a stable, continuous sensation. The frequency depends upon various factors like luminance, color, contrast, etc.


19.) Difference between CMY and HSV color models.

CMY Model HSV Model
A color model described with the primary colors cyan, magenta, and yellow (CMY) is useful for defining color output to hard-copy devices. The HSV model uses color descriptors that have a more natural appeal to the user. Color function in this model is hue (H), saturation (S) and value(V).
Hard-copy devices such as plotters produce a Color image by coating a paper with color pigments. To give color specification, a user selects a spectral color and the amounts of black and white that are to be added to obtain different shades, tints, and tones.


20.) What is dithering?

Ans. The name dithering is used in different contexts. Primarily, it defines techniques for approximating halftones without reducing resolutions pixel: grid patterns do. But the term is also applied to halftone approximation methods using pixel grids and sometimes it is used to define to color halftone approximation only.

Random values added to pixel intensities to breakup contours are referred to as dither noise.



Part -2: RTU Computer Graphics and Multimedia


21.) List out the various properties that describe the characteristics of light.


  • Reflection
  • Refraction
  • Dispersion
  • Interference
  • Diffraction


22.) What is an animation?

Ans. Computer Animation usually defines any time sequence of visual transformation in a scene. In adding to the dynamic area with translations or rotations, computer-generated animations could exhibit time innovation in object dimension, color, transparency, or surface texture. Animations often transition from one object shape to another.


23.) Define Keyframe systems.

Ans. Key-frame systems are specialized animation languages designed to generate the in-between frames from user-specified keyframes. Each object in the scene is described as a set of rigid bodies connected at the joints and with a limited number of degree of freedom. In-between frames are generated from the specification of two or more fey frames. Motion paths can be given by kinematic description as a set of spline curves or physically based by specifying the force acting on the object to be animated.


24.) What is Fractals?

Ans. Fractals are those who have the property of a shape that has the same degree of roughness no matter how much it is magnified. A fractal appears the same at every scale.


25.) What is a Turtle Graphics Program?

Ans. Turtle Graphics is a procedure in computer graphics for programming vector graphics utilizing a relative cursor upon a Cartesian plane. Turtle graphics is a vital characteristic of the Logo Programming language.

The following functions describe the turtle.

  • Position of the turtle (x, y)
  • Title of the turtle 0 the angle from the x-axis.


26.) List the attributes of turtle in graphics.

  • Turtle graphics has three attributes
  • Current Position location
  • Current direction Orientation
  • Pen


27.) Differentiate Mandelbrot sets and Julia sets.

Mandelbrot sets Julia sets
A very famous fractal is obtained from the Mandelbrot set, which is a set of complex values z that do not diverge under squaring transformation z0=z
k=1, 2, 3.
For some functions, the boundary between those points that move towards those points that move towards infinity and those that tends toward a finite limit is a fractal. The boundary of the fractal is called the Julia set.
It is the black inner fragment, which develops to consist of a cardioid along with several wart-like circles glued to it. Its border is complicated, and this complexity can be explored by zooming in on a portion of the border Julia sets are extremely complicated sets of points in the complex plane. There is a various Julia set Jc for each value of c.


28.) What is the Koch curve?

Ans. The Koch curve can be drawn by separate line into 4 equal segments with scaling method 1/3., and middle 2 segments are so adapted that they form adjustment sides of an equilateral triangle.


29.) What are Morphing and tweening?

Ans. Transformation of object shape from one form to another is known as morphing.

Tweening is the process, which applies to animation objects defined by a sequence of points, and that change shape from frame to frame.


30.) What are Peano curves?

Ans. A fractal curve can fill the plane and therefore have a dimension of two. Such curves are called Peano curves.


31.) What is a Scripting system?

Ans. Scripting systems allow object specifications and animation sequences to be defined with a user input string. From the script, a library of different objects and motions can be constructed.


32.) Define refresh/frame buffer.

Ans. Picture definition is saved in a memory area known as the refresh buffer or frame buffer. This memory area keeps the set of intensity values for all the screen points.

The frame buffer is where the image generation data is stored in the method of Video Display Monitors like CRT, Raster Scan, Random Scan, LCD, LED, etc.


33.) What is the resolutions?

Ans. The maximum number of point that can be presented without overlap on a Cathode Ray Tube is indicated to as the resolutions.

Resolution is the number of points per centimeters which can be plotted crosswise and vertically, although it is established as the total number of points in each direction.


34.) Define Window and viewport.

Ans. A world-coordinate area selected for display is known as a window.

An area on the display device to which a windows is mapped is known as a viewport.


35.) Distinguish between window port and viewport?

Ans. A portion of a picture that is to be presented by a window is known as Window port.

The display method of the part selected or the design in which the selected element is viewed is called a viewport.


36.) What are blobby objects?

Ans. Some objects do not provide a fixed shape but change their surface features in certain motions or when in proximity to other objects. These objects are called as blobby objects since their shapes display a certain degree of fluidness.


37.) What are the Spline curves?

Ans. The name spline is a flexible strip used to generate a smooth curve through a designated set of points. In computer Graphics, the name spline curves define to any combined curve create with polynomial portions fulfilling specified continuity methods at the edge of the pieces.


38.) What is the advantages of B spline over Bezier curve?


  • The degree of B-spline polynomial can be set separately of the number of control points.
  • B-Spline allows local authority over the shape of a spline curve or surface.
  • A Bezier curve is a particular polynomial task, usually either cubic or quadratic, that describes a curve that goes from point A to point B given some control points in between. A Bezier spline is a collection of n of these.


39.) What is a Rasterizations?

Ans. The phase of determining the appropriate pixels for representing images or graphics object is called a rasterization.


40.) How will you represent a curve in graphics?

Ans. The curve can be created from an input set of mathematical tasks defining the objects or from a set of user-specified points. When tasks are specified, a package can project the describing equations for a curve to the display plane and plot pixel methods along the path of the projected plane.


41.) Mention the uses of Chromaticity Diagram?

Ans. The chromaticity diagram is generally used to calculate a color against a gamut. The assumption is that if the chromaticity of the color distortion within the gamut line, then the color maybe copied on that device, or maybe described by that color system.


42.) What is interactive computer Graphics?

Ans. Interactive computer Graphics like a website, it is only beneficial if a visitor browser it and no two visitors are precisely alike. It defines the website must provide the interaction of the customer with a variety of skills, interests, and end objective. Interactive computer graphics contains the user's interaction.


43.) What does it mean by RGB?

Ans. RGB is a color model; it is an additive color image in which red, green, and blue lights are added composed in various methods to reproduce a broad display of colors. The term of the model comes from the labels of the three additive primary colors, red, green, and blue. The main objective of the RGB color model is for the sensing, defining, and display of pictures in electronic systems, such as televisions and computers, though it has also been utilizing in conventional photography.


44.) What is VDU?

Ans. A monitor or display known as a visual display unit is a portion of electrical machinery which displays images created by an appliance such as computers, without producing a permanent data. The monitor composes the display device, circuitry, and an enclosure. The display device in modern monitors is usually a thin film transistor liquid crystal display (TFT-LCD), while previous monitors use a cathode ray tube (CRT).


45.) What is Projection?

Ans. The process of displaying 3D into a 2D display unit is called a projection. The projection changes 3D objects into a 2D projection plane.


46.) What are the advantages of electrostatic plotters?

Ans. They are quicker than pen plotters and large-quality printers.
New electrostatic plotters contain a scan-conversion capability.
Color electrostatic plotters are feasible. They make different passes over the paper to plot color images.

47.) What are the advantages of laser printers?

Ans. Large speed, precision, and economy.

  • Low-cost to maintain.
  • Quality printers.
  • Lasts for high time.
  • Toner power is very in-expensive.


48.) List some 3D viewing devices.

  • Stereoscopic systems
  • Virtual reality systems


49.) What is meant by Addressability?

Ans. Addressability is the number of particular dots per inch (d.p.i.) that can be developed. If the location of the current dot is (x, y), then the next dot will be (x + y), (x + y + 1), etc.


50.) What is scan-code?

Ans. When the key is pressed on the keyboard, the keyboard auditor places a code import to the key pressed into a part of memory called a keyboard buffer. This code is known as the scan-code.


Read More RTU Previous Year Question Paper

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RTU CGM (Computer Graphics And Multimedia): Q And A

We have prepared this post keeping in mind the students of Rajasthan Technical University, Kota, which is based on the syllabus of rtu cgm (computer graphics and multimedia) which is only intended to prepare the students for any kind of interview and viva.

rtu computer graphics


Collections of Top Questions of RTU CGM


1.) What is scan conversion?

Ans. A major task of the display processor is digitizing a picture definition given in an application program into a set of pixel-intensity values for storage in the frame buffer. This digitization process is called scan conversion.


2.) Write the properties of video display devices?

Ans. Properties of video display devices are persistence,resolution, and aspect ratio.


3.) What is rasterization?

Ans. The process of determining the appropriate pixels for representing picture or graphics object is known as rasterization.


4.) Define Computer graphics.

Ans. Computer graphics remains one of the most existing andrapidly growing computer fields. Computer graphics maybe defined as a pictorial representation or graphicalrepresentation of objects in a computer.


5.) Name any four input devices?

Ans. Four input devices are keyboard, mouse, image scanners,and trackball.


6.) Write the two techniques for producing color displays with a CRT?

Ans. Beam penetration method, shadow mask method.


7.) What is vertical retrace of the electron beam?

Ans. In raster scan display, at the end of one frame, the electron beam returns to the left top corner of the screen to start the next frame.


8.) Short notes on video controller?

Ans. Video controller is used to control the operation of the display device. A fixed area of the system is reserved for the frame buffer, and the video controller is given direct access to the frame buffer memory.


9.) What is bitmap?

Ans. Some system has only one bit per pixel; the frame buffer is often referred to as bitmap.


10.) Differentiate plasma panel display and thin film electro luminescent display?

Ans. In plasma panel display, the region between two glass plates is filled with neon gas. In thin film electro luminescent display, the region between two glasses plates are filled with phosphor, such as zinc sulphide doped with manganese.


11.) What is resolution?

Ans. The maximum number of points that can be displayed without overlap on a CRT is referred to as the resolution.


12.) What is horizontal retrace of the electron beam?

Ans. In raster scan display, the electron beam return to the left of the screen after refreshing each scan line, is called horizontal retrace of the electron beam.


13.) What is filament?

Ans. In the CRT, heat is applied to the cathode by directing a current through a coil of wire, is called filament.


14.) What is pixel map?

Ans. Some system has multiple bits per pixel, the frame buffer is often referred to as pixel map.


15.) Write the types of clipping?

Ans. Point clipping, line clipping, area clipping, text clipping and curve clipping.


16.) What is meant by scan code?

Ans. When a key is pressed on the keyboard, the keyboard controller places a code carry to the key pressed into a part of the memory called as the keyboard buffer. This code is called as the scan code.


17.) List out the merits and demerits of Penetration techniques?

Ans. The merits and demerits of the Penetration techniques areas follows. It is an inexpensive technique. It has only four colors. The quality of the picture is not good when it is compared to other techniques. It can display color scans in monitors. Poor limitation etc.


18.) List out the merits and demerits of DVST?

Ans. The merits and demerits of direct view storage tubes[DVST] are as follows. It has a flat screen. Refreshing of screen is not required. Selective or part erasing of screen is not possible. It has poor contrast Performance is inferior to the refresh CRT.


19.) What do you mean by emissive and non-emissivedisplays?

Ans. The emissive display converts electrical energy into lightenergy. The plasma panels, thin film electro-luminescent displays are the examples.The Non-emissive are optical effects to convert the sunlightor light from any other source to graphic form. Liquid crystal display is an example


20.) List out the merits and demerits of Plasma paneldisplay?

Ans. Merits. Refreshing is not required. Produce a very steady image free of Flicker. Less bulky than a CRT.Demerits. Poor resolution of up to 60 d.p.i. It requires complex addressing and wiring. It is costlier than CRT.


21.) What is persistence?

Ans. The time it takes the emitted light from the screen to decay one tenth of its original intensity is called as persistence.


22. What is Aspect ratio?

Ans. The ratio of vertical points to the horizontal points necessary to produce length of lines in both directions of the screen is called the Aspect ratio. Usually the aspect ratio is ¾.


23.) What is the difference between impact and non-impactprinters?

Ans. Impact printer press formed character faces against an inked ribbon on to the paper. A line printer and dot-matrix printer are examples.Non-impact printer and plotters use Laser techniques,inkjet sprays, Xerographic process, electrostatic method sand electrothermal methods to get images onto the papers. Examples are: Inkjet/Laser printers.


24.) Define pixel?

Ans. Pixel is shortened forms of picture element. Each screen point is referred to as pixel or pixel.


25. What is frame buffer?

Ans. Picture definition is stored in a memory area called frame buffer or refresh buffer.


26.) Where the video controller is used?

Ans. A special purpose processor, which is used to control the operation of the display device, is known as video controller or display controller.


27.) What is run length encoding?

Ans. Run length encoding is a compression technique used to store the intensity values in the frame buffer, which store search scan line as a set of integer pairs. One number each pair indicates an intensity value, and second number specifies the number of adjacent pixels on the scan line that are to have that intensity value.


28.) What is point in the computer graphics system?

Ans. The point is a most basic graphical element & is completely defined by a pair of user coordinates (x, y).


29.) Write short notes on lines?

Ans. A line is of infinite extent can be defined by an angle of slope q and one point on the line P=P(x,y). This can also be defined as y=mx+C where C is the Y intercept.


30.) Define Circle?

Ans. Circle is defined by its center xc, yc and its radius in user coordinate units. The equation of the circle is (x-xc) + (yyc)= r2.


31.) What are the various attributes of a line?

Ans. The line type, width and color are the attributes of the line.The line type include solid line, dashed lines, and dotted lines.


32.) What is anti aliasing?

Ans. The process of adjusting intensities of the pixels along the line to minimize the effect of aliasing is called anti aliasing.


33.) What is Transformation?

Ans. Transformation is the process of introducing changes in the shape size and orientation of the object using scaling rotation reflection shearing & translation etc.


34. What is translation?

Ans. Translation is the process of changing the position of an object in a straight-line path from one coordinate location to another. Every point (x , y) in the object must under go a displacement to (x|,y|). the transformation is:x| = x + tx ; y| = y+ty


35.) What is rotation?

Ans. A 2-D rotation is done by re positioning the coordinates along a circular path, in the x-y plane by making an angle with the axes. The transformation is given by:X| = r cos (q + f) and Y| = r sin (q + f).


36.) What is scaling?

Ans. A 2-D rotation is done by re positioning the coordinates along a circular path, in the x-y plane by making an angle with the axes. The transformation is given by:X| = r cos (q + f) and Y| = r sin (q + f).


37.) What is shearing?

Ans. The shearing transformation actually slants the object along the X direction or the Y direction as required. ie; this transformation slants the shape of an object along a required plane.


38.) What is reflection?

Ans. The reflection is actually the transformation that produces a mirror image of an object. For this use some angles and lines of reflection.


39.) What are the two classifications of shear transformation?

Ans. X shear, y shear


40. Name any three font editing tools.

Ans. ResEdit, FONTo grapher


41. Differentiate serif and sans serif fonts.

Ans. Give one example Serif fonts has a little decoration at the end of the letter,but serif font has not. Times, new century schoolbook is the examples of serif fonts. Arial, optima are examples for sanserif fonts.

42.) Distinguish between window port & view port?

Ans. A portion of a picture that is to be displayed by a window is known as window port. The display area of the part selected or the form in which the selected part is viewed is known as view port.

43.) Define clipping?

Ans. Clipping is the method of cutting a graphics display to neatly fit a predefined graphics region or the view port.

44.) What is the need of homogeneous coordinates?

Ans. To perform more than one transformation at a time, use homogeneous coordinates or matrixes. They reduce unwanted calculations intermediate steps saves time and memory and produce a sequence of transformations.


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