Lambertian reflection

  You want to measure the albedo of a small test surface with Lambertian reflection characteristics. You illuminate the surface with a light source from an angle β=60˚ with respect to the surface normal. In that direction, your light source has radiant intensity equal to I=5 W/str. The light source is at R1 = 1 meter of distance from the target surface. Then you take a picture of the surface with a camera that points directly at the test surface (i.e. the camera’s optical axis intersects the surface at an angle of θ=30˚). The camera is at R2 = 1.5 meters from the test surface. The camera has f-number equal to 5.6. If the irradiance measured at the central pixel of the camera is Ecam =3 mW/m2 , what is the albedo of the surface? Exercise 2 Consider a perfectly specular planar surface (a mirror), and define a reference system with its origin on the surface, X and Y axes lying on the surface, and consequently Z axis vertical with respect to the surface. Suppose you place a camera with its optical center at position (X = 1 m, Y = 1 m, Z = 3 m) with respect to this reference system. The camera is oriented such that its optical axis intersects the origin of the reference system (X=Y=Z=0; this point is on the mirror’s surface). What is the location (Xb,Yb,Zb) at which you should place a light bulb such that (1) the camera sees the reflection of the light from the bulb on the mirror, and (2) the light bulb is at 2 meters of height with respect to the specular surface (i.e., the Zb coordinate of its location is 2 m)?