If you were to look straight down into a pool of water, you would be able to see through the minimal reflectivity of the surface to the elements in the water below. When you look down at a reflective surface, the amount of reflection is determined by the viewing angle. Reflectivity - Applying the same principle as before, that things are going to act oddly at the edge of our glass, we next throw into the mix the Fresnel Effect. When we look at the edge of the glass, the same thing is true, therefore we are looking at more 'object' and should treat these edges as less transparent (Fig.04). Conversely, if you were standing on the top of Mount Everest and could look both north and south from the summit, you might be able to see 150 miles in each direction (a total of 300 miles) before the Earth curves away and you are looking into space. Think about it this way: when a space shuttle exits the atmosphere by flying straight up (off the perpendicular normal of the Earth) it only goes through 62 miles of air to reach outer space. At the edges of the glass we are actually looking through a denser amount of material. But let's examine what happens to our material as it gets close to the edge. Let's break these elements down for a closer look: Transparency - As mentioned, glass is transparent. Finally, glass is a refractive surface, bending light as it enters this medium which is denser than the air around it. It is a specularized surface, and thusly not very diffuse in terms of surface properties. Second, glass is reflective, but again we must examine how this reflectivity works. While this is the most obvious, we cannot overlook the subtleties inherent in this transparency due to the thickness of the surface as perceived. The first thing to note is that, of course, glass is a transparent entity. There are several components which need to be created. My render settings are listed here as well (Fig.02 - 03). Next, I duplicate out a few of these, and set up the scene. Whilst simple, we need to make sure that the revolved surface (constructed here using a NURBS) is thicker at the base (just like a real pint glass). Our first step is to create the geometry for the glasses. The user of this tutorial should note that I have also used Mental Ray as my renderer, with Final Gathering, Global Illumination, Caustics, and Image Based lighting used for optimal realism. We will also use Mental Ray's Dielectric Material and new Mia_material. For this demo we will utilize Maya's Blinn material, Ramp texture, and Sampler Info utility.

Glass shows up black in arnold for maya