TrueSpace4 3-D from Caligari Corp. costs far less than Hollywood-style 3-D software but still has amazing powers, whether you want to simulate a vehicle crash, design software for education or simply make an eye-popping Web graphic.

If you like animation, the program has a fairly simple interface for turning still objects into animated scenes. You can even set up "interrelation statements" that make the screen change color, say, when a button is pressed in a training application.

To test animation, I tried a truly hard task: making a person walk. It was no picnic but it was easier than I expected.

Images have skeletons as well as deformable skin, so what you do is electronically remove the skin and move the skeletal structure along at key points. Other connected areas then follow suit as in a marionette.

Once the animation is ready in wire-frame mode, you re-apply the skin. A professional designer would do a lot of tweaking at this point, but most users will be satisfied with TrueSpace4's human forms on the first or second try.

Like previous versions, TrueSpace4 is strong at lighting effects. Precise lighting makes a virtual room look realistic, whereas bad lighting can make anything look fake.

The trick behind the program's impressive "Hybrid Radiosity" engine is calculation of the amount of light diffusion, as opposed to merely calculating the travel direction of light rays, as many programs do. Diffusion is better, because some surfaces are not lit directly at all--they diffuse light from other sources.

The engine also can calculate the color differences between direct and indirect lighting. Colored surfaces in the real world tend to bleed--for example, a red wall bleeds light onto a white floor.

In testing TrueSpace4, I designed a room in the approximate paint colors of the Government Computer News Lab and added white fluorescent lighting. The effect was accurate even in the corners of my virtual room.

If you want to know how light is going to play through a window, making it look cheery or like prison bars, the program can render realistic soft shadows with a penumbra effect. In my sparse little virtual lab, I added some windows and rotated a projection light to simulate the sun. It looked pretty real.

Materials can be shaded with more textures than I have seen in any similarly priced design program. For example, you can texture any object with wood, marble, reflective metal, mirror, chrome or a whole list of other materials.

Rendering fog is one of the hardest effects, because fog particles are transparent in small quantity, then translucent and finally opaque in large masses. The mathematical calculations for fog generation are quite complex.

It took me a week of reading the 550-page user guide and many hours of trial and error to become marginally competent in TrueSpace4. That is true of most design software. Keep in mind too that anything less than a top-of-the-line machine with a high-end 3-D video card will deprive you of the best TrueSpace4 has to offer.

Once mastered, TrueSpace4 becomes an invaluable resource for the designer accustomed to working manually, and for the animator looking for an easier way to bring concepts to life.

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TrueSpace

Caligari Corp., Mountain View, Calif.

Telephone: 1-800-351-7620

Web address: www.caligari.com

Price: $595

Pros:

+ Realistic lighting effects

+ Good still images and animations

+ Outstanding for hard jobs such as fog and human animations

Cons:

- Steep learning curve

- Advanced hardware required

Grade: B+

Real-life requirements: Windows 95, 98 or NT, 400-megahertz Pentium II, 64 megabytes of memory, 3-D video card with at least 4 megabytes of memory, 20 megabytes free storage space on hard disk, CD-ROM drive.