Jon22: The Website of Jonathan Dobres

Which of these wine glasses is the real one? Ooooh which of these things is not like the other, which of these things just doesn’t belong? If you said D, you’re wrong. If you said C, you’re also wrong. In fact, all of these wine glasses are computer generated. I made them last night. What can I say? When I called Ratatouille “inspiring,” I meant it.

There was one particular scene in the movie where I found myself mesmerized by the wine glasses. It’s funny, in a way. When an amateur 3D artist (me) sets out to learn his program of choice, it seems the first complex object he tries to create is always a wine glass. There are roughly seven million tutorials on how to make one. Most 3D graphics packages allow the user to create the basic 3D solids—sphere, cube, cylinder, pyramid, torus, and teapot—with the press of a button. A wine glass, however, requires a bit more than simple button presses. The radial symmetry of the glass and its simple, unbroken surface make it an ideal target for those who wish to create a more complex, but not terribly difficult object.

The process, shown above, is as follows:

1. Create a spline (a 3D line) in the shape of the glass. Splines are invisible to the final image. They are essentially just a bit of math floating through 3D space. Splines are a starting point, and are used as outlines, guideposts, and foundations for true 3D objects. Make sure when creating the spline for the glass that you account for the thickness of the wine glass as well.
2. Using a magical little function that some programs call Lathe and others call Revolve, the half-outline of the wine glass is now a full 3D object, even if you can’t see it in this schematic view. Imagine that there’s a carousel centered at the far left of the outline in Figure 1, and we’ve told that outline to spin around it, leave copies of itself along the way, and then connect the copies to form a surface. Tada! Wine glass.
3. The 3D view of the wine glass. Not bad for ten minutes’ work, right?

So, having created his wine glass, the novice generates an image from the model and, disappointingly, ends up with something that looks like Figure A, which is little different from the unadorned 3D view from within the program.

Here the novice learns a second important lesson about creating a convincing wine glass; it needs texture. Imagine a newly created 3D object as a plain cardboard box. Textures (also known in other programs as Materials or Shaders) are like wrapping paper. The metaphor is somewhat inadequate, since textures often affect the look of an object’s volume as well as its surface. Textures can make a plain cube look like a block of wood, a chunk of brushed metal, or a piece of Jello.

The unadorned wine glass in Figure A has only a plain, off-white texture applied. It’s as basic as you can get, and it looks like plastic or Styrofoam. Isn’t it awfully convenient that Pixar’s first movie was all about toys? The limits of the day’s technology met a wisely chosen story.

Figure B is a basic attempt at creating a glass material—fully transparent, refractive, and partially reflective. There are a number of reasons why it doesn’t look good, but the biggest is that this glass texture is taking some mathematical shortcuts, taking into account only the surface of the wine glass, and not treating it as an object with any volume.

Figure C is much better. I’m using a much more advanced texture here. This texture does most of the work for me, and I’m not going to pretend that I understand the math. The key thing, I believe, is that this texture is smart enough to treat the object as if it has thickness, not just surface. Still, there are problems. For example, the stem of the glass practically melts into the background.

Figure D is my best attempt. I’ve darkened the glass somewhat to make it stand out against the plain white background, but importantly, I’ve borrowed an old photographer’s trick and placed some large white reflection cards behind the camera. Reflection cards exist solely to give shiny objects in a plain environment something to reflect, thus making the object look a little more interesting and showing off its contours. This technique is used all the time in real photography of glassware, watches, and jewelery.

Since wine glasses are very transparent and very reflective, it should be obvious that the glass’s environment is just as important as the glass itself. Below I’ve created a basic room that throws in some more objects and attempts to simulate some natural sunlight. Note the glowing effect seen in the shadows of the glass objects. These are called “caustics,” and they happen all the time in the real world, most notably with a magnifying glass and some toy soldiers. The green bowl was created using the same method as the wine glass.

Not too shabby for a basic setup, I think. So, what have we learned? When you set out to create a realistic wine glass, it takes more than a well proportioned model. You also have to take into account the texture, the lighting, and the surrounding environment. It’s not real unless it all comes together.