Lets imagine we are looking through the front face of a cubic fish tank, with some goldfish swimming inside. The other sides, the top and the bottom of the tank are covered up. Our view into the tank shows the goldfish swimming up and down, turning, going behind a rock and moving behind and in front of one another.
As a fish turns we can see its left side and then its right side. If we are going to make an animation of the goldfish in the tank we need to know what the fish looks like from the left side, the right side and from any other point of view we care to choose.
If we had a 2D animation package we would need to be very good artists to make the necessary drawings as our fish turns, even if the computer helps by doing the 'in- betweens'. A 3D package is very clever because it will draw the appropriate view of the goldfish, but you don't get something for nothing, you will still have to tell the computer what the goldfish looks like.
There is a very subtle difference between drawing a goldfish and defining what a goldfish will look like! You can think of the difference between an architects plan and an artists drawing of a house. This analogy with the plan of the house is quite a good one. The plan tells you everything about the house but it doesn't show you what it will look like. A plan enables the builders to put the house together, you can then walk round and through the house to see what it looks like from wherever you want. However every time an artist wants to draw the house from a different view point he or she will have to start from scratch. The same thing applies to goldfish or any other object. A plan contains much more information than a drawing but it is not what we like to look at, a plan doesn't sell many houses, an artists impression may do!
The essence of 3D animation is that it takes a plan for objects and draws them as an artist would. The plan that we use is not quite the same as an architect's plan and thus we prefer to call it a model. In the example of our goldfish, the model provides information on what a goldfish looks like and it is stored in the computers memory.
You are now probably asking yourselves; What do we mean by a model that we can store in the computers memory? It can't be anything physical such as clay, plastic or balsa wood!
It has got to be numbers. What numbers? How many? What do the numbers mean? How do we use them to get the computer to draw a lifelike goldfish?
We will now attempt to answer these questions, but first, here is another question. What do you see when you look at a goldfish?
You see it's skin (it's surface). Thus the minimum that the model must do is to represent the surface of the fish. There is no point in modelling internal bits, they won't be visible. This surface is likely to be quite irregular (fins, eyes etc.). So how do we represent the surface in terms of computer data? Click on the link below to find out.