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END TERM EXAMINATION
DECEMBER 2015
BCA (Vth SEMESTER)

## COMPUTER GRAPHICS (BCA-305)

Time: 3 Hrs MM: 75

Note: Attempt any five questions including Q No. 1 which is compulsory. Select one question from each unit.

Q1: Explain any five of the following

(a) The role of Video Controller in Raster Display Systems
(b) Conceptual framework for interactive graphics.
(c) Matrix Representation of 3D scaling
(d) Transformation as a change in a coordinate system.
(e) Polygon mesh
(f) Octree

UNIT-1

Q2:
(a) What do you mean by scan conversion? Derive the equation for scan converting a line using Breshnam's line drawing algorithm.

(b) Differentiate between Random Scan and Raster Scan. Explain random scan display processor with suitable diagram. ( See Answer)

Q3:
(a) What is clipping? Explain Cohen-Sutherland line clipping algorithm.

(b) Let R be the rectangular window whose lower left-hand corner is at L(-3, 1) and upper right hand corner is at (2,6). Find the end point codes for the following points according to Cohen Sutherland algorithm of the line clipping:
A(-4,2) B(-1, 7) C(-1, 5) D(3,8) E(-2, 3) F(1,2) G(1,-2)
H(3,3) I(-4, 7) J(-2, 10)

UNIT-II

Q4:
(a) Find the general form of transformation N which maps a rectangular window with the extent Wxmin to Wxmax in x direction and Wymin to Wymax in y direction on a rectangular viewport with x extent vxmin to vxmax and y extent vymin to vymax.

(b) Explain the transformation matrices for various 2D transformation in homogeneous coordinates.

Q5:
(a) Find the complete viewing transformation that maps a window in a world co-ordinates with x extent 1 to 10 and y extent 1 to 10 on to a viewport with x extent ¼ to ¾  and y extent 0 to ½ in normalized device space and then maps to a window with x extent ¼ to ½ and y extent ¼ to ½ in the normalized device space, into a viewport with x extent 1 to 10 y extent 1 to 10 on the physical display device.

(b) Find the normalised transformation N which uses the rectangle A(1,1), B(5,3), C(4,5) and D(0,3) as a window and a normalised device screen as a viewport.

UNIT-III
Q6:
(a) Define parametric Bicubic surface. Discuss Hermite surface in details.
(b) State and prove a property of Bezier Curve with four control points.

Q7:
(a) Explain how Bezier curves are represented parametrically. Consider a Bezier curve having control points P1(20,0), P2(0, 20), P3(80, 40), P4(40, 0)

(b) What is CSG? Discuss various user interfaces for solid modelling.

UNIT-IV

Q8:
(a) What do you mean by hidden surfaces? Discuss Z buffer method for removing hidden surfaces.

(b) Define projection. Differentiate between parallel and perspective projection with suitable examples. (😌See answer)

Q9:
(a) "Hidden surfaces should be removed" why? Discuss Painter's algorithm for hidden surfaces examples.

(b) Define orthographic projection. Discuss different applications of parallel and perspective projections.