Computer Graphics (COMP136) Quiz 5

This is a standard multiple choice test. Each question has only one correct answer. Please mark that one answer clearly on the answer sheet provided. If any question ahs more than one answer filled in, it will be marked wrong. There are XX questions. You will have XX minutes.

1) As part of the shadow volume algorithm, silhouette edges must be tracked. These are tracked by

a) noting where the first plane normal dotted with the vector to the viewer goes negative

b) noting where the first plane normal dotted with the vector to the light goes negative

c) noting where the vector to the viewer dotted with the vector to light goes negatived) noting where the vector to the viewer crossed with the vector to the light goes

negative2) Which of the following was not a use for the accumulation buffer?

a) depth of fieldb) image processingc) motion blurd) higher resolution images

3) In class, we discussed several reasons for using pipelines. Which of the following was NOT one of those reasons?

a) increasing the FLOPs via perpendicular executionb) simplifying the problem by breaking it into piecesc) solving several separate pieces at the same time: i.e. parallelism d) avoiding bottlenecks in execution

4) The Graphics pipeline has several stages. Which of the following is NOT a responsibility of the geometry portion of the pipeline?

a) clipping objects external to the viewing windowb) applying all affine transformsc) converting the geometry into fragmentsd) applying the projective transform

5) The Graphics pipeline has several stages. Which of the following is NOT a responsibility of the fragment processing portion of the pipeline?

a) texture lookupsb) performing XOR with what is in the color bufferc) inside/outside testingd) depth buffer lookups

6) We discussed two variants to the perspective projection transform. The first mapped all primitives to a plane at z = d. The second created a normalized volume centered at (0, 0, 0) with all sides of length 2 units. Which of the two was required for z-buffering?

a) map to a plane (z=d)b) map to a volume (corners from (-1, -1, -1) (1, 1, 1))

7) True or false. Using Cohen-Sutherland line clipping, it is impossible for a vertex to be labeled 1111.

a) trueb) false

8) Which of the following five line segments can be trivially rejected on the first pass of Cohen-Sutherland line clipping?

a) ABb) CDc) EFd) GHe) IJ

9) We discussed three line clipping algorithms in class. Which was the most efficient algorithm that could extend to 3D?

a) Cohen-Sutherlandb) Nicholl-Lee-Nichollc) Liang-Barsky

10) We discussed three line clipping algorithms in class. Which was the only to use the parametric form of a line to solve for both clip points and culling?

a) Cohen-Sutherlandb) Nicholl-Lee-Nichollc) Liang-Barsky

11) We discussed three line clipping algorithms in class. Which could decide all lines which were visible after only solving for the regions of P1 and P2?

a) Cohen-Sutherlandb) Nicholl-Lee-Nichollc) Liang-Barsky

12) The triangle on the right is filled according to which inside/outside rule?a) Even/Oddb) Winding Number

13) In class, we discussed two forms of Polygon Clipping. Which was executed by clipping all polygon edges against the viewing screen edges one viewing screen edge at a time?

a) Weiler-Athertonb) Sutherland-Hodgeman

14) In class, we discussed two forms of Polygon Clipping. Which had the difficulty of having to maintain “cached” directions while pursing a different direction?

a) Weiler-Athertonb) Sutherland-Hodgeman

15) In class, we discussed two forms of Polygon Clipping. Which had the benefit of never creating connecting lines between separate pieces of a polygon with a concavity?

a) Weiler-Athertonb) Sutherland-Hodgeman

16) True or false. Given a line starting at (0, 0) ending at (13, 5), it’s length is the same as its number of pixels.

a) trueb) false

17) In class, we discussed primary and secondary directions for line algorithms. True or false: Given a line with end points (7, 18) and (14, 5), the primary direction is y.

a) trueb) false

18) In class, we discussed that using integer arithmetic only increased the speed of algorithms. Which of the following line algorithms used integer only arithmetic to rasterize lines?

a) Bresenham’s Line Algorithmb) The DDA Line Algorithmc) The FFTW Line Algorithm

19) In class, we discussed various line algorithms. Which one used a “decision parameter” to solve for how to change the secondary pixel?

a) Bresenham’s Line Algorithmb) The DDA Line Algorithmc) The FFTW Line Algorithm

20) In class, we briefly discussed curve algorithms. A great benefit of these algorithms was the ability to mirror across axis to solve for only a portion of the curve. Which of the following allowed for 8 mirror images?

a) parabolasb) hyperbolasc) circlesd) ellipses

21) In class we discussed several algorithms to fill polygons. Which of the following was the one used by real rasterizers?

a) 4-Fill Polygonsb) 8-Fill Polygonsc) Scan-Line Polygonsd) Boundary Fill Polygons

22) In class we discussed several algorithms to fill polygons. Which of the following required edges to be rasterized only for distinct y values?

a) 4-Fill Polygonsb) 8-Fill Polygonsc) Scan-Line Polygonsd) Boundary Fill Polygons

23) True or false. The 8-Fill Polygon technique will correctly fill the triangle shown below when seeded at the position shown with an X.

a) trueb) false

24) Which of the following is not an object-space hidden surface removal algorithm?a) Back-Face Cullingb) Depth Bufferc) Painter’s Algorithm

25) Which of the following hidden surface removal algorithms potentially causes a bottleneck in the Graphics Pipeline? (We discussed this in class. There’s only one correct answer.)

a) Back-Face Cullingb) Depth Bufferc) Painter’s Algorithm

26) Which of the following hidden surface removal algorithms can be used along with either of the other two (i.e. it solves part of the problem, but not all)

a) Back-Face Cullingb) Depth Bufferc) Painter’s Algorithm

27) Which of the following is not a limitation of GPU Programmability mentioned in class?a) Whole GPU Pipe must be traversed every timeb) One 4-tuple output per fragmentc) One 4-tuple output per vertexd) One 4-tuple output per final pixel resolution

28) True or false. OpenGL Extensions need not be supported by all drivers and hardware.a) trueb) false

29) True or false. One of the reasons OpenGL versions are infrequent is because new versions are not backward compatible with old versions.

a) trueb) false

30) Which of the following GPU programming languages does NOT work for OpenGL?a) Cgb) HLSLc) GLSL

The next several problems refer to the rendering equation. For your reference, it is rewritten below:

31) Which of the following describes the purpose of the ν (nu) portion of the rendering equation?

a) reflection of light from p” across p’ to pb) geometry function (0 if p’ not visible from p, 1/r2 otherwise)c) intensity of light from p’ to pd) emitted light from p’ towards p

32) Which of the following describes the purpose of the ε (epsilon) portion of the rendering equation?

a) reflection of light from p” across p’ to pb) geometry function (0 if p’ not visible from p, 1/r2 otherwise)c) intensity of light from p’ to pd) emitted light from p’ towards p

33) If p’ were of the material type “Mirror” instead of “Window” which of the following functions would change value?

a) νb) εc) ρ

34) True or false. “Utah” graphics falls into the category of “Global Illumination”. a) trueb) false

For the following set of questions, consider the line which starts at location (5, 14) and ends at position (21, 2).

35) How many pixels will there be in this line?a) 12b) 16c) 20d) 24

36) Which is the primary direction?a) xb) yc) z

37) With the DDA algorithm, what will be the amount (amt in notes) added to the secondary component each time through the loop?

a) -1/2b) 1/2c) -3/4d) 3/4e) -4/3