Exercise 24.3

Consider an infinitely long cylinder of radius $r$ oriented with its axis along the $y$-axis. The cylinder has a Lambertian surface and is viewed by a camera along the positive $z$-axis. What will you expect to see in the image if the cylinder is illuminated by a point source at infinity located on the positive $x$-axis? Draw the contours of constant brightness in the projected image. Are the contours of equal brightness uniformly spaced?