Computer Science 455 Instructor: R. P. Burton Seventh Quiz December 7-8, 2005 Name _________________________________________ Score ____________/39 1. The mapping from RGM to CMY (and vice versa) a.involves only subtraction b.involves averaging (division) c.involves calculations more complicated than addition, subtraction, multiplication, and division (a) 2. Where in/on the HSV hexacone are the pure hues? a.on the top b.around the perimeter of the top c.on the vertical axis d.on the “panels” representing the sides e.on the inside, but not on the vertical axis (b) 3.The HLS color model could be characterized accurately as a distortion of the _____ color model. a.HSV b.CMY c.RGB d.XYZ (a) 4.Contemporary graphics systems are capable of representing and presenting 224 colors. Contemporary users are able to draw much more information from a static scene than are users of earlier systems due, in large part, to the relatively large number of colors which can be presented simultaneously. The user should maximize the number of different colors used. a.true b.false (b) 5.The pixel on the display surface corresponds to _____ in the pinhole camera model. a.a pixel b.a portion of the film surface c.nothing (b) 6.Of the four mechanisms for light transport, which group is accommodated by traditional ray tracing? a.Specular (whether reflection or transmission) b.Diffuse (whether reflection or transmission) c.Reflection (whether specular or diffuse) d.Transmission (whether specular or diffuse) (a) 7.A small object moving across the screen (sometimes hit and sometimes not) produces _____ aliasing. a.spatial b.temporal (b) 8.Which of the following solves the antialiasing problem? a.supersampling b.adaptive supersampling c.statistical supersampling d.stochastic raytracing e.(none of the above solves the problem) (e) 9.What is the advantage of stochastic ray tracing, relative to conventional supersampling? a.higher resolution b.more efficiency c.elimination of grid patterns d.(all of the above) (c) 10.For ray-sphere intersection, the ray is represented _____; the sphere is represented _____. a.explicitly, explicitly b.explicitly, parametrically c.parametrically, explicitly d.implicitly, parametrically e.parametrically, implicitly f.(none of the above) (e) 11.What sort of equation is solved to find the intersection of a ray and a sphere? a.a linear equation b.a quadratic equation c.a cubic equation d.a quartic equation (b) 12.In solving for t (in ray-sphere intersection), when the part under the radical sign is 0, there a.is no intersection point b.is one intersection point c.are two intersection points (b) 13.In the geometric solution for ray-sphere intersection, which of the following is not detected in the pretests? a.determination if the ray originates inside the sphere b.determination if the (infinitely extended) ray hits the sphere c.determination if the ray originates outside and points away d.(everything here is can be detected in the pretests) (d) 14.Spherical inverse mappings tend to ______ any associated texture at the poles. a.expand b.contract c.present, without distortion, (b) 15.The general approach to ray-plane intersection is fundamentally _______ the general approach to ray-sphere intersection. a.the same as b.different from (a) 16.The point/polygon inside/outside test for raytracing can be solved using the inside/outside tests considered previously in the semester. a.true b.false (a) 17.Suppose the plane intersected by the ray is 3x + 5y -2z + 8 = 0. The test for intersection should be done in the _____ plane. a.xy- b.yz- c.zx- (c) 18.What is the primary reason that a solution to the ray/box intersection problem is interesting? a.because scenes contain boxes b.because bounding boxes can improve the efficiency of ray tracing (b) 19.The approach to the ray/box intersection problem represents the ray ______ and the box ______. a.explicitly, explicitly b.explicitly, parametrically c.parametrically, explicitly d.implicitly, parametrically e.parametrically, implicitly f.(none of the above) (f) 20.There is a general solution for the intersection (and reflection) of a ray with (and from) all of the following except a.cylinders b.cones c.ellipsoids d.paraboloids e.hyperboloids f.(no exceptions here) (f) 21.The inverse mapping for a circle, as presented in the class, a.treats the circle as a “cookie cutter” which selects a section of a quadrilateral b.maps from polar coordinates to Cartesian coordinates (b) 22.The inverse mapping for a cone, as discussed in class a.opens up the cone and uses it as a “cookie cutter” which selects a section from a quadrilateral b.wraps the quadrilateral around a cylinder and then tapers the cylinder (b) 23.For purposes of raytracing, as discussed in class, each ray has a.a single wavelength b.a multiplicity of wavelengths, represented the energy distribution (a) 24.The angle of refraction depends on a.the medium b.the wavelength of the incoming light c.(both a and b) (b) 25.What color is a highlight on a copper kettle produced by incident white light? a.white b.copper-colored (b) 26.Fractal geometry had its beginnings with a.the ancient Egyptians b.da Vinci c.Mandelbrot (c) 27.Fractal geometry has application to all of the following except a.chemistry b.meteorology c.military science d.(no exceptions here) (d) 28.The length of a fractal curve is a.determined by the fractal dimension of the curve b.limited by the “ceiling” (least upper bound) of the fractal dimension of the curve c.infinite (c) 29.The Koch snowflake illustrates _______ self-similarity. a.exact b.statistical (a) 30.Why are fractals generated with functions in the complex plane? a.because fractals are “complex;” they don’t exist in the real world (only forgeries exist) b.to separate x values from y values c.to prevent functions from diverging to infinity (b) 31.A 2D Julia set has a.length b.area c.volume d.something between length and area e.something between area and volume (a) 32.Random midpoint displacement methods select points along an edge with a.all points being equally likely b.points forming clusters along the edge c.the likelihood of a point being inversely related to its proximity to the center d.the likelihood of a point being inversely related to its proximity to an end (d) 33.Which of the following fractal dimensions is least likely to represent observable phenomena? a.1.20 b.2.30 c.3.40 (c) 34.What does 1/fbeta noise do? a.no one knows; it’s been a mystery ever since it was discovered b.it scales randomness in time (b) 35.The closer two notes are in the melody of an LDS hymn, the more likely they are to be similar. a.true b.false (a) 36.Which of the following quantities is likely to be the “smallest.” a.the length of a fractal curve b.the length of a program to generate a fractal curve of arbitrary detail c.the length of time required to compute a fractal curve or arbitrary detail (b) 37.Which of the following does not have a stable orbit a.sin(x) (in radians) b.cos(x) (in radians) c.sqrt(x) (x real and positive) d.sqr(x) (x real and positive) e.(all have stable orbits) (d) 38.If f(z) = z2 , what would inverse iteration use? a.1/ z2 b.sqrt(z) c.1/sqrt(z) (b) 39.For ____________, zk+1 = zk2 + c. a.Mandelbrot b.Julia c.Mandelbrot and Julia (c)