By Admin | 09/22/2016 | 5 Comments
Reflections done incorrectly seem to be a pet peeve of mine. Doubtless you've seen examples of them in magazines, websites, and TV.
I suppose I could go into all the mathematics and the compound angles involved—but I think it will be easier just to say that reflections are simply a copy of the object shown, using the object's opposite angle(s)—in a 3D space.
Since most reflective surfaces depicted in art are simply a flat, level plane of some kind—a table, a lake, a river, etc. this should be somewhat familiar.
On a level surface there will be no need to calculate more than 2 compound angles.
For simplicity's sake, I have reduced these two diagrams to highlight only one angle (the angle the object has in relation to the reflective surface).
However, if we take a closer look at the two diagrams we can see that not only is there the angle relative to the surface, but also the angle relative to the viewer (this provides objects in the scene with depth and vanishing points). In fig. 1, the viewer is slightly above the first object since we can see the top of the cylinder. The reflection is an inverted copy of the original, but you'll notice that eventhough the object's reflection is opposite—the top of the cylinder is still only visible on the original. This is due to the fact that the verticle vanishining point is still dependent on the viewer's location relative to the object being reflected.
In fig. 2, yet another angle is introduced, as the cylinder is itself rotated slightly toward the viewer so as to make the bottom of the object visable. In this instance, the object has a reflection that has the opposite angle of approach as well as an opposite angle of rotation.
Thus we see that when dealing with level reflective surfaces the angle of the reflected objects are exactly inverted—and, since vanishing points are always in relation to the viewer's position relative to the object being reflected—the verticle vanishing point is inverted or flipped, but the vanishing point(s) along the horizon line is left unchanged.
But what about when the reflective surface isn't level? This is where things get crazy. In these cases you must also take the surface angle into consideration when deciding how the object will be reflected. You can quickly be in need of calculating 3 or more compound angles in these cases.
Reflections can quickly get complicated, but, nothwithstanding the painfulness of the task, it is more important that the object is reflected properly. If you wish to maintain credibility, that is.
So, do incorrect reflections bother you? Do they make you cringe? Do they make you vurp? Tell me about it below.