524 Part V: On a 3D Spree

Do You See What I See?

In the computer graphics world, rendering is the process of illuminating a set of 3D objects with one or more imaginary lights and then creating a more-or- less realistic picture of the results. (No, computer programmers didn’t have lard on their minds when they borrowed the word rendering. Hand-drawn pictures of building facades were called renderings long before computers got into the act.)

A single example of this technique is called a still rendering. Multiple frames strung together produce computer animation. The objects that you see in movies such as Avatar or How to Tame Your Dragon are first created as 3D models and then rendered frame by frame. This process can take immense amounts of time even on ultrafast graphics workstations, and a major movie is usually done on rendering farms of 20,000–30,000 computers (that’s right; 20 to 30 thousand!).

AutoCAD is best at creating still renderings. If you want to create photorealistic rendered animations, you need to use other software programs, such as Autodesk 3ds Max. Even if you use other animation programs, AutoCAD can still be useful for developing the initial 3D models.

Rendering has steadily improved in speed and usability as PCs have become faster and programmers improved their rendering algorithms. Rendering simple scenes is now practical on a mainstream PC, and a fast PC can create some impressive images in a reasonable amount of time. Rendered images are useful for previewing how your models will work in real life and also can be powerful tools for sales and marketing communications for your company. A (rendered) picture can be worth quite a bit more than a thousand words, especially in today’s economy.

People who do a lot of rendering and want higher-quality, photorealistic results usually use programs other than AutoCAD to render their models. Autodesk 3ds Max, Cinema 4D (Maxon), and AccuRender (Robert McNeel & Associates) are three popular photorealistic rendering programs. Most rendering programs can import 3D models from AutoCAD DWG files, but some people use specialized 3D modeling programs to do their modeling as well.

Visualizing the Digital World

Rendering allows you to see how a final product might look before it’s manufactured or built in the real world (see Figure 23-6); it definitely helps to sell a concept to a client. Although you can show a client a hidden line or shaded view of a 3D model, showing a photorealistic render just helps make it feel that much more real when looking at it.

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