(1) (10pts) Show that an affine transformation can map a circle to an ellipse, but
cannot map an ellipse to a hyperbola.
(2) (10 pts) Show that there is a three parameter family of projective
transformations which fix a unit circle at the origin (i.e. they map a unit circle at
the origin to a unit circle at the origin). What is the geometric interpretation of
this family?
(3) (20pts) Suppose we are given a 3X4 camera matrix:
3.53e+2
-1.03e+2
7.07e-1
3.39e+2
2.33e+1
-3.53e-1
2.77e+2 -1.44e+6
4.59e+2 -6.32e+5
6.12e-1
-9.18e+2
Compute the camera center and the calibration parameters
4) (20 pts) Consider 3 points a,b,c lying on a straight line in an image. They are
images of points A,B and C lying on a line in 3D. Show how to compute the
vanishing point of line ABC from the ratio: ab/bc that can be measured in the
image.
5) (5pts) In a 3X4 camera matrix, what is the geometric meaning of the 4 column
vectors?
6) (35 pts) (Affine rectification) Consider the image attached. Read the image into
matlab and use matlab to perform the calculations necessary for the following
questions:
(a) Calculate two vanishing points.
(b) Find the image of the line at infinity
(c) Calculate a homography that maps the line at infinity to its canonical position.
This homography produces an affine rectification. Apply this homography to the
image. Show your result
(7) (50 pts) ((Projective reconstruction using coplanar points). Assume two sets of
four known coplanar points in the scene {A,B,C,D} and {E,F,G,H} giving images
{a,b,c,d} and {e,f,g,h} for an non calibrated camera with camera center O.
Consider an unknown point M in the scene producing an image m.
(a) Show how to determine the viewing ray Om.
(b) Use (a) to develop a method for finding the camera center.
(c) Repeat (a) and (b) for the case where we are given 6 points in
space and their images (instead of two sets of four coplanar points).
(8) If P is a (3X4) camera projection matrix and C is the camera center (in projective
coordinates), then show that PC=0.