how do the images below illustrate this principle? I'm a little confused.
@crabbage The plot shows the amount of light specularly reflecting off the table when viewed at different angles. Let's say that our viewing angle from the table's normal is 10 degrees in the left-most image, 45 degrees in the middle image, and 80 degrees in the right-most image. The plots states that, as the angle from normal increases, the specular term (or Fresnel term) becomes stronger. As a result, the table starts to look much more mirror-like in the right-most image (e.g., you can see the reflection of the book and wall in the right-most image much more clearly than the left-most image).
So the angle changed is actually the angle we view the object, not the angle between the book and table... I think I misunderstood it in class
@elenagong The only thing that is changing in the bottom set of images is the viewing angle---yes. Lighting and objects are fixed.