JNTU
JNTU B.Tech III COMPUTER GRAPHICS Previous Question Paper (October - 2020 - R16)
Answer any five questions. All questions carry equal marks.
Main
Describe about CRT with neat sketch.
Answer
A Cathode Ray Tube (CRT) is a vacuum tube device that produces images by projecting an electron beam onto a phosphor-coated screen. It serves as the fundamental display technology for early computer monitors and televisions.
The primary components of a CRT include:
- Electron Gun: Consists of a heating filament, cathode, and control grid. It emits a stream of electrons through thermionic emission. The control grid regulates the intensity of the beam, which determines the brightness of the pixel on the screen.
- Focusing System: Uses electrostatic or electromagnetic lenses to ensure the electron beam converges into a tight, sharp point when it strikes the screen.
- Deflection System: Consists of horizontal and vertical deflection plates (or coils) that create electric or magnetic fields to steer the electron beam across the screen in a raster scan pattern.
- Phosphor-Coated Screen: The inner surface of the screen is coated with phosphors. When the high-velocity electron beam hits the phosphor, the kinetic energy is converted into light, creating a visible spot.
- Acceleration Anode: A high-voltage anode accelerates the electron beam towards the screen to ensure sufficient energy for luminescence.
The operation follows a Raster Scan process, where the electron beam sweeps across the screen row by row, from top to bottom. The intensity of the beam is modulated at each point to create the desired image. The persistence of the phosphor ensures the image remains visible for a short duration, requiring the beam to refresh the entire screen periodically (typically 60-85 times per second) to prevent flickering.
Sketch Description: The CRT structure is a funnel-shaped glass tube. At the narrow neck, the electron gun assembly is positioned. Moving towards the wider end, the deflection plates are placed perpendicular to each other. The wide, flat front face of the tube is the screen, which is internally coated with a layer of phosphor material to display the output.
Develop and implement a flood-fill algorithm to fill the interior of any specified area.
Answer
The Flood-Fill algorithm is used to fill connected regions of a display by starting from a seed point and recursively or iteratively coloring neighboring pixels until a boundary color is encountered. It is particularly useful for filling areas defined by a specific boundary color.
The algorithm can be implemented using a 4-connected or 8-connected approach. The basic recursive procedure for 4-connected filling is as follows:
- Check if the current pixel (x, y) is already the fill color or the boundary color. If so, return.
- Set the pixel (x, y) to the desired fill color.
- Recursively call the function for the four neighbors: (x+1, y), (x-1, y), (x, y+1), and (x, y-1).
A simple pseudocode implementation:
void floodFill(int x, int y, int fillColor, int boundaryColor) { if (getPixel(x, y) != boundaryColor && getPixel(x, y) != fillColor) { setPixel(x, y, fillColor); floodFill(x+1, y, fillColor, boundaryColor); floodFill(x-1, y, fillColor, boundaryColor); floodFill(x, y+1, fillColor, boundaryColor); floodFill(x, y-1, fillColor, boundaryColor); } }Explain about beam penetration method with neat sketch.
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Explain the Sutherland and Cohen subdivision algorithm for line clipping.
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Write a short note on viewing transformation.
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Briefly explain about Reflection.
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Give a detailed note about Hermite interpolation.
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Give brief note about the approaches followed for clipping in 3-D space.
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Explain the various methods for generation of curves and surfaces.
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What are the characteristics of perspective projections? Explain.
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Explain in detail about BSP trees.
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Write a short note on Warnock's algorithm.
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Discuss about the techniques to achieve the simple animation effects.
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Describe about the raster animations.
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