Anchoring the New York skyline, the 1,776-foot tall Freedom Tower stands as a memorial to liberty, the evening sun glinting off its steel, downtown New York reflected in its glass panels.

Problem: The Freedom Tower doesn't exist, at least not outside the mind and computer screen of architect David Childs. But looking at the image, it's hard to tell what's real and what's only on the drawing board.

Welcome to the new world of architecture rendering, where plans look real, and where reality and anticipation mix.

Whether it's New York's Freedom Tower or Roanoke's new art museum, "artist's conceptions" are no longer simple ink drawings or watercolors. Just as faster, better computers and software have allowed Hollywood's special effects studios to create realistic worlds out of mere pixels, similar technology lets architecture and engineering firms create photorealistic models of projects long before the first brick sees a drop of mortar.

For architects, this technology can be a terrific tool. It helps them visualize a final product in a way no hand-drawn image could. And it can help sell a design to a client -- it can show not just how a building will look, but how it will look in its environment and how different materials will affect that look.

But it's a tool with downsides as well -- in time, perception and cost.

Looking good

Before computers appeared on everyone's desktops, the image an architect or designer presented a client was usually a colored sketch or watercolor. It gave a basic idea of what a building would look like, while later in the process those clients would see more-detailed sketches, plans and blueprints.

Today, computers allow an architect to create an image of the completed project from the get-go, something that can be used as a sales tool. Just as home buyers like to imagine their own furniture in the houses they look at, someone planning a building likes to imagine the finished product in place.

There's also the public relations aspect.

Realistic images of architects' visions for the World Trade Center's replacement made the rounds of the media long before the final design was chosen, allowing public comment to be based on something more than a sketch.

But it's not just nationally-known projects that get this treatment. Images of the new Art Museum of Western Virginia have been circulating, along with strong opinions about the facility. Those opinions are based solely on architect Randall Stout's computer-generated renderings.

Those renderings, and others on display at the current museum in Center in the Square, are fairly straightforward. They're an artist's conceptions, although the artist used a mouse and computer tablet instead of a pen or brush.

These images are not simply pictures made using painting or image-editing software such as Photoshop. Architecture and engineering are more exact than that, especially later in the process. Stairs are a particular width, windows a particular brand, floors a particular pattern.

Because of that, architects and designers build an environment much the way you might populate a dollhouse, by placing pre-made objects: This window goes here, that chair goes there.

The computer knows the characteristics of each -- how it casts a shadow, how it reflects the light, how it fits in a space. And these aren't generic windows or chairs; designers have libraries of specific brands and models. If a client is using Herman Miller Aeron chairs, then that's what will appear. The computer generates an image that takes into account the characteristics of every piece and surface.

The devil in the details

Creating those exact-as-possible environments is what Teresa Martin and Stephen Smiroldo do for architecture and engineering firm Hayes, Seay, Mattern & Mattern's corporate imaging department.

Working with the architect who designed the space, they make it real -- adding the wall and floor coverings, the furniture, the lighting, and various and sundry objects that each need to be placed individually using existing textures or 3-D images, or by downloading new ones from Web sites specializing in architecture and design.

They place those objects, and the computer calculates how the scene changes, rendering an image that is about as close to reality as possible. In some cases, it's almost impossible to tell what's a photograph and what's computer generated.

Sometimes they take a few liberties. For an exterior image, for example, they might add cars and people in front of the building. Usually that adds a touch of realism, but not always. In one case, Martin and Smiroldo added an aircraft flying in an image of a building at Wright-Patterson Air Force Base. Unfortunately, the image they chose was of a Navy jet.

Government clients, they said, tend to want a lot of detail in renderings, down to the particular model of telephone on the desks. Being able to meet that kind of request is one advantage to using the technology. But it helps more than just the clients, Smiroldo said. For example, architects love it. "The option to see it allows them to get into an area -- it gives new life."

They also like the information that's available. Using a technique called Building Information Modeling, every element in an image isn't just a pretty picture; it's also linked to a database that contains a detailed list of its features.

"You can click on a window and get 35 pieces of information about it," said Sandy Workman, HSMM's director of communications. Change any of that information -- make a 35-inch window 36 inches, or an Aeron chair into a Steelcase model -- and the picture is updated to reflect it.

The client side

When choosing an architect for their new building, the trustees of the Art Museum of Western Virginia relied on models and portfolios. But once Stout had been tapped for the job, decisions about the details were made based on his computer models, which allowed the construction committee to see exactly how things would look.

It's the difference between choosing room paint based on a square of color at Lowe's or seeing an image of exactly what the space will look like.

Deanna Gordon, who served on the committee, said Stout presented the trustees with photorealistic images of the museum during the planning process. The committee used those to modify the design, including "[the] size and sale of gallery space, offices, where the elevators would go, where the loading dock would go," she said.

Later, Stout's illustrations let the committee choose the details -- finishes, flooring, even the colors of the restroom tiles.

"He was able to send us, by computer, images of what these materials would look like," Gordon said "I don't think we could have done nearly the same thing with drawings."

A step further than those sophisticated artists' renderings are photo composites, in which a proposed building is carefully placed into a photograph of the site.

Martin said it's a way to give clients a taste of the possibilities. "It's taking a photograph and showing what it could, possibly, look like," she said.

These professional-quality images don't simply mean dropping a building into a photo. The building has to match the size and perspective of the land. "Photo composites are challenging," Martin said, in part "because you have to match the angle of the camera." Shadows need to fall the right way and reflections need to be just right or people will sense something is wrong.

Downsides

Low tolerance for errors is one downside of making images look too real. If Martin and Smiroldo create a sophisticated rendering early in the process, they run the risk of clients thinking it's the finished product, even though it may not take into account the realities of the location, not to mention later decisions by clients.

"If you make it look so realistic," Martin said, "people will think that is how it's going to be, when that's what it could be." Expectations raised, they can be unhappy with the final version that's more down-to-earth.

On the other hand, clients who see a realistic image are also more likely to focus on less-important details early in the process. Martin might put in a blue carpet as an example, getting the client sidetracked into a discussion of floor coverings when they haven't settled on the basic layout yet.

And people's perceptions of the process are colored by using consumer-level software to work with photos. They think making a change is a simple thing. It's not.

In fact, because architectural renderings have to take into account thousands of objects and textures, not to mention all the light from windows and lamps, rendering a single image can take 16 hours.

Imagine waiting a day for a new image to come out, only to have a client say, "You know, I think I liked the other chairs better."

Of course, sometimes the realism of the renderings can save a client from making a bad choice.

When HSMM renovated Center in the Square in 2000, Center management requested several changes to the design for financial reasons. By giving them a realistic rendering of the changed design, HSMM was able to show them how it would look: Not good.

"Basically they realized what a mistake it was," Smiroldo said. Instead, they were able to find a less-expensive solution -- using patterned carpet instead of tile, for example.

Still images aren't the only tool architects and designers have. "Fly-through" animations, 3-D computer models, and interactive site images are all in the tool kit.

Somewhere, today, someone is undoubtedly making plans for what will stand on the Victory Stadium site. An amphitheater? A smaller stadium? Another museum? One thing is certain: Whatever it is, we'll see it in glorious detail long before it's built.