Three-Dimensional Models and Visualizing Change

Why planners build models

Plans are usually written in words, tables and flat drawings, and most people find those hard to picture. A zoning amendment might allow buildings up to a certain height, but few residents can tell from the text what that means for sunlight on their street. A three-dimensional model makes the question visible. It shows height, bulk, spacing and how a proposed building sits next to its neighbors.

Models are used to explain a proposal to the public, to help a review board evaluate a design, to compare alternatives and to test whether a rule produces the shapes it was meant to. They are tools for understanding, and like any tool they can be used well or badly.

Types of models and renderings

Physical massing models. A block-scale model made of foam, wood or printed parts shows the overall shapes of buildings without detail. Because people can walk around it and move pieces, it works well in workshops. The abstract look is useful: since it does not pretend to show finished materials, it keeps attention on size and placement.

Digital massing models. The same idea on a screen. Simple blocks representing existing and proposed buildings can be viewed from any angle, and rules such as height limits or setbacks can be tested quickly.

Detailed 3D models. These add facades, windows, roofs, trees and street furniture. They are more engaging but invite more judgments about style, which may distract from the questions of scale and fit that the model was supposed to illuminate.

Still renderings. A single image, often produced from a detailed model, shown from a chosen viewpoint. Renderings are common in project announcements because they are easy to circulate.

Animations and walkthroughs. Moving views let people experience a street or space as a pedestrian might. They also give the maker many more opportunities to shape the impression.

Immersive tools. Virtual reality and similar tools let a person look around inside a model. They can convey scale strongly, though the technology is not always available and some people find it uncomfortable.

What models do well

• Showing relationships. Height next to existing buildings, the width of a street against the buildings that frame it, and the size of a plaza are easier to grasp in 3D.
• Testing rules. A city can model the buildings that current rules would allow and compare them with a revised set of rules before adopting changes.
• Comparing alternatives. Showing two or three schemes at the same scale and from the same viewpoint helps a group discuss trade-offs.
• Including more people. Someone who cannot read a technical drawing can often respond to a model, which broadens who can take part in public meetings.
• Examining shadows and views. Many tools can simulate the shadows cast at different times of year, which is useful where sunlight on streets or neighboring homes is a concern.

How a picture can persuade more than it informs

A rendering is not a photograph of the future. It is a designed image, and every choice in it affects the impression it gives. Some of the most common choices include:

• Camera angle and lens. A wide-angle view from a distance can make a large building appear smaller or a narrow street seem spacious. A view from high above can shrink the apparent effect on people on the ground. Pedestrian-level views usually show more of what a resident would actually feel.
• Season, weather and light. Warm evening light, clear skies and full foliage make nearly any project look inviting. A winter, overcast or midday view might look different.
• People and activity. Crowds of smiling people, cafe tables and cyclists suggest a lively place, though nothing in the design guarantees that they will come.
• Vegetation. Mature trees drawn at planting time imply a leafy street years before it will exist. Real trees may take many years to reach the size shown, and some will not survive.
• Surroundings. Leaving out neighboring tall buildings, parking, traffic or utility equipment makes a scene look cleaner than it will be. Showing existing buildings in pale gray and new ones in color can also draw the eye.
• Materials and finishes. Renderings often show idealized materials. Final specifications may change because of budget or availability.
• Omission of what is not decided. A model may show a finished plaza when funding for maintenance is not settled.

None of this requires bad intent. Designers want their work to look good, and a persuasive image is part of that. The issue is that an audience may take a flattering image as a commitment. The same concern applies in reverse: an opponent can commission an unflattering view that exaggerates a building’s bulk.

Practices that make models more honest

Planners and designers can reduce the risk with a few habits.

1. Show existing and proposed conditions from the same viewpoint, using the same lens, light and season, so that viewers can compare directly.
2. Provide several viewpoints, including street-level ones near where residents live, not only flattering aerial views.
3. Label what is firm and what is illustrative, such as final materials, landscaping, signs and street furniture.
4. Use photographs from real locations as the base for photomontages, and say how the proposed building was added.
5. Include shadow studies for key times of year when sunlight is a concern.
6. Make the model data available, within reason, so that others can check the heights and footprints against the proposed rules.
7. Avoid presenting a rendering as a guarantee. Design review boards and the public often return to images later to ask why the finished project looks different.

How readers can evaluate a rendering

When you see a rendering of a proposal, ask a few questions. From where was the view taken, and what would it look like from the place you would actually stand? What season and time of day is shown? Are existing buildings and traffic included? Which features are required by the approval and which are decorative? Is there a plain diagram or table showing height, floor area and setbacks? Pictures are most informative when they sit beside the numbers, not in place of them.

Used with those cautions, 3D models are valuable for helping communities see change before it happens. They support discussion best when everyone involved knows they are illustrations, made by people with a point of view, and treats the numbers behind them as the real commitments.