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Iclicker questions for ECSE-4750 Computer Graphics, Rensselaer Polytechnic Institute, Fall 2014

Thurs 9/4/2014






  1. What is your major department/program?
    1. EE
    2. CSYS
    3. CS
    4. GSAS
    5. Other





  2. What is your class?
    1. Junior
    2. Senior
    3. Grad
    4. Other





  3. What is your favorite platform/OS?
    1. Windows
    2. Linux
    3. Mac
    4. Other





 

 

Mon 9/8/14
  1. Color printing on a sheet of paper exemplifies
    1. additive color
    2. subtractive color
    3. multiplicative color
    4. divisive color
    5. exponential color





  2. Red is a primary color of which color space?
    1. additive color
    2. subtractive color
    3. multiplicative color
    4. divisive color
    5. exponential color





  3. Consider a pinhole camera as discussed in slide 12 of ppt presentation 1_5. Let d=2. To where does the point (1,3,-2) project? Use the equation on that slide. x/z/d should be parenthesized as x/(z/d).
    1. (-1,-3,-2)
    2. (1,3,-2)
    3. (1,3,2)
    4. (1/2, 3/2, 1)
    5. (1/2, 3/2, -1)





  4. Major components of the OpenGl model as discussed in class are:
    1. Objects, viewer, light sources, planets, material attributes.
    2. Still cameras, video cameras, objects, light sources.
    3. Objects, viewer, light sources, material attributes.
    4. Colored objects, black and white objects, white lights, colored lights
    5. Flat objects, curved objects, near lights, distant lights.





  5. When using a pipeline to clip a 3D object, how many stages can be used?
    1. 1
    2. 3
    3. 4
    4. 6
    5. 8





  6. The carpet is an example of
    1. diffuse reflection
    2. specular reflection
    3. environment mapping
    4. bump mapping
    5. how to save money





  7. In the OpenGL pipeline, the Primitive Assembler does what?
    1. fits together pieces of ancient Sumerian pottery.
    2. rotates vertices as their coordinate systems change.
    3. creates lines and polygons from vertices.
    4. finds the pixels for each polygon.
    5. reports whether the keyboard and mouse are plugged in correctly.





Thurs 9/11/14
  1. The default OpenGL camera is:
    1. At the origin and looking up the Y axis.
    2. At (1,0,0) and looking towards the origin.
    3. At {$ X=\infty $} and looking towards the origin.
    4. At the origin and looking down the Z axis.
    5. At the origin and looking up the Z axis.





  2. To draw into only part of the graphics window you would call:
    1. gl.drawpart
    2. gl_Position
    3. gl.viewport
    4. gl.window
    5. There's no builtin routine; you have to scale your graphics yourself to achieve this.





Mon 9/15/14
  1. What buffer is used by OpenGl to do hidden surface removal?
    1. Closest object buffer
    2. Color buffer
    3. Depth or Z buffer
    4. Hidden-surface buffer
    5. Ray-trace buffer





  2. If you do not tell OpenGL to do hidden surface removal, and two object overlap the same pixel, then what color is that pixel?
    1. OpenGL throws an error.
    2. the closer object
    3. the farther object
    4. the first object to be drawn there
    5. the last object to be drawn there





  3. gasket2 has this code: var points=[ ]; ... points.push(a,b,c); What does push do here?
    1. Appends new entries to the end of points.
    2. Inserts new entries at the start of points.
    3. Overwrites the first entries of points.
    4. Overwrites the last entries of points.
    5. Throws an error because we didn't specify a size for points.





  4. Look at this CIE chromaticity diagram. If you wanted to make white by mixing one spectrally pure color with the pure color with wavelength 600 nm, what wavelength would that other color be?
    1. 400
    2. 485
    3. 535
    4. 580
    5. It's not possible, because purple is not a spectrally pure color.





Thurs 9/18/14
  1. Which of the following 3D rotation methods is vulnerable to gimbal lock?
    1. Euler angles
    2. matrix
    3. quaternion
    4. vector







  2. Which of the following 3D rotation methods has the intuitive axis-angle API?
    1. Euler angles
    2. matrix
    3. quaternion
    4. vector







  3. Which of the following 3D rotation methods makes it easy to combine two rotations?
    1. Euler angles
    2. matrix
    3. quaternion
    4. vector







  4. When rotating an object, what can happen to an object?
    1. Straight lines might turn into curves.
    2. Straight lines stay straight, but angles might change.
    3. Straight lines stay straight, and angles don't change, but distances may change, either longer or shorter.
    4. Straight lines stay straight, and angles don't change, but distances might get longer.
    5. Straight lines stay straight, and angles and distances don't change.







Mon 9/22/14
  1. If i and j are quaternions, what is i+j?
    1. -k.
    2. 0.
    3. 1.
    4. i+j, there is no simpler representation.
    5. k.







  2. If i and j are quaternions, what is ij?
    1. -k.
    2. 0.
    3. 1.
    4. i+j, there is no simpler representation.
    5. k.







  3. The quaternion i represents what rotation?
    1. 180 degrees about the x-axis.
    2. 90 degrees about the x-axis.
    3. 180 degrees about the y-axis.
    4. 90 degrees about the y-axis.
    5. no change, i.e., 0 degrees about anything.







  4. What is the quaternion for the rotation that is two rotations of the quaternion i?
    1. 180 degrees about the x-axis.
    2. 90 degrees about the x-axis.
    3. 180 degrees about the y-axis.
    4. 90 degrees about the y-axis.
    5. no change, i.e., 0 degrees about anything.







Thurs 9/25/14
  1. A mouse reports which type of position?
    1. Absolute
    2. Relative







  2. A tablet reports which type of position?
    1. Absolute
    2. Relative







  3. Which of these can easily be a logical keyboard?
    1. a physical keyboard
    2. a tablet with handwriting recognition
    3. a virtual keyboard on the screen, selecting letters with the mouse
    4. voice input and recognition
    5. all of the above







  4. Why would you want to send a variable to a vertex shader that has the same value for every vertex?
    1. the vertex's coordinates
    2. the vertex's color
    3. the object's global orientation
    4. the location of the global light source







Mon 9/29/14
  1. The parametric equation of a line through the points (1,1) and (2,3) is:
    1. P = (1,1) + t(1,0) + u(0,1)
    2. P = (1,1) + t(1,1)
    3. P = (1,1) + t(1,2)
    4. P = (1,1) + t(2,3)
    5. P = t(1,1) + u(2,3)







  2. The parametric equation for the plane through the points (1,0,0), (0,1,0), (0,0,1) is
    1. P = (1,0,0) + t(0,1,0) + u(0,0,1)
    2. P = (1,0,0) + t(-1,1,0) + u(-1,0,1)
    3. P = t(1,0,0) + u(0,1,0) + v(0,0,1)
    4. P = t(1,0,0) + u(-1,1,0) + v(-1,0,1)
    5. P = (1,0,0) + t(0,1,0)







  3. The normal vector to the plane through the points (1,0,0), (0,1,0), (0,0,1) is
    1. (1,0,0)
    2. {$\left( 1/\sqrt{3}, 1/\sqrt{3}, 1/\sqrt{3} \right) $}
    3. (-1, 0, 0)
    4. 3
    5. (1/3, 1/3, 1/3)







  4. You call gl.BufferSubData to do what?
    1. to add or replace part of the buffer in the GPU.
    2. to define a submarine object.
    3. to subtract some data in the buffer.
    4. to tell the GPU to look for a pattern and substitute any occurrences,
    5. to tell the GPU to use a subroutine instead of the main program.







Thurs 10/2/14
  1. (Sometimes I write vectors horizontally since they're easie to type.) The 3D homogeneous point (1,2,3,4) is equivalent to which Cartesian point.
    1. (1,2,3)
    2. (1,2,3,1)
    3. (1,2,3,4)
    4. (1/4, 2/4, 3/4)
    5. (1/4, 2/4, 3/4, 4/4)







  2. Translating the 2D homogeneous point by (1,2,3) by (in Cartesian terms) dx=1, dy=2 gives which new homogeneous point?
    1. (1,2,3)
    2. (1,2,3,4)
    3. (2,4)
    4. (2,4,3)
    5. (4,8,3)







  3. Rotating the 2D Cartesian point (0,1) by {$90^o$} gives what:
    1. (1,0)
    2. (-1,0)
    3. (0,1)
    4. (0,-1)
    5. (-.7,.7)







  4. (These are 3D Cartesian points.) Let a=(1,0,0) and p=(2,3,4). Then the component of p that is parallel to a is
    1. (0,3,4)
    2. (0,3/2,2)
    3. (1,0,0)
    4. (2,0,0)
    5. (2,3,4)







  5. Let a=(1,0,0) and p=(2,3,4). Then the component of p that is perpendicular to a is
    1. (0,3,4)
    2. (0,3/2,2)
    3. (1,0,0)
    4. (2,0,0)
    5. (2,3,4)







  6. If a 3x3 rotation matrix has eigenvalues {$1, -\frac{\sqrt{2}}{2}+\frac{\sqrt{2}}{2}i, -\frac{\sqrt{2}}{2}-\frac{\sqrt{2}}{2}i $}, then what is the rotation angle (in degrees)?
    1. 0
    2. 45
    3. 90
    4. 135
    5. 180







  7. If you use a separate buffer that's 16 bits deep to store object ids for picking, then how many different object ids can you have? Assume that the frame buffer is 1024x1024.
    1. 16.
    2. 24.
    3. 65536.
    4. 1,048,576.
    5. 16x1024x1024.







  8. I want a matrix M that has this property: for all vectors p, {$Mp = \begin{pmatrix}-1&0&1\end{pmatrix} \times p$}. M =
    1. {$\begin{pmatrix} 0&-1&0\\1&0&1\\0&-1&0 \end{pmatrix} $}
    2. {$\begin{pmatrix} 0&1&0\\-1&0&-1\\0&1&0 \end{pmatrix} $}
    3. {$\begin{pmatrix} 0&1&0\\1&0&1\\0&1&0 \end{pmatrix} $}
    4. {$\begin{pmatrix} 1&0&-1\\0&0&0\\-1&0&1 \end{pmatrix} $}
    5. {$\begin{pmatrix} 1&0&-1\\1&0&-1\\1&0&-1 \end{pmatrix} $}







  9. What is the angle (in degrees) between these two vectors: (1,0,0), (1,2,3)?
    1. 0.
    2. {$ 1/\sqrt{13} $}.
    3. {$ 1/\sqrt{14} $}.
    4. {$ \arccos(1/\sqrt{13}) $}.
    5. {$ \arccos(1/\sqrt{14}) $}.







  10. This is a homogeneous 3D translation matrix: {$\begin{pmatrix} 2&0&0&2\\ 0&2&0&3\\0&0&2&4\\ 0&0&0&2 \end{pmatrix} $} Where is the Cartesian point (0,0,0) translated to?
    1. (0,0,0)
    2. (1,3/2,2)
    3. (1,3/2,2,1)
    4. (2,3,4)
    5. (2,3,4,2)