Plans and designs for stadiums frequently change over time. What's the reason? Tim Newcomb talks to prominent architects to find out.

Nothing pretties up a blueprint quite like an architectural rendering, often a needed component to help promote a stadium, explain it or even just make it understood. But what happens when those renderings morph over the course of a project, such as with D.C. United’s latest proposal? And, most importantly, why do those renderings change?

Renderings change all the time. It is part of the business. Even the timing of when renderings first appear for a project varies; sometimes they're released as part of a design competition to win a project, even before interviews with the clients. Sometimes renderings don’t appear until well into the project.

“A common thread is they are just a tool a lot of time to build excitement and engagement,” Greg Brown, AECOM architect, tells SI.com. “One reason why they vary so much is projects like these stadium projects—any high-profile project—architects are going to try to win that job. They present ideas to win the work and then lots of times the big commitment and design thinking that goes into it are done with no input or direct feedback from the prospective ownership group.”

Even a winning design, then, will see a major change once the owner actually gets involved.

Often an early rendering simply exists to present a big idea. But then the “budget gets real, program requirements get real, site constraints get real, lots of new information or preferences or ideas owners might have evolve designs,” Brown says.

D.C. United's proposed stadium (grab the slider in the center to see old vs. new)

Jon Knight, senior principal and architect at Populous, the same firm designing soccer stadiums in D.C., Minnesota and Orlando, tells SI.com the only way most people can understand a project is with a picture.

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“At the outset of the project, when the program is undefined and budget has not been defined, it is very often a public process, a conversation with city agencies,” Knight says.

Renderings take an initial stab at an early vision or concept and help convey early thoughts, “but as we develop the design, our projects are very public and there are a lot of other voices involved,” he says.

“Designs change over time and every time it changes, there is a new visual for it. They change as often as they need to change.”

As the architectural world ramps up technology, the ability to produce renderings has sped up too.

Orlando City's proposed stadium (different architects)

Knight, at Populous for 26 years, says sports architecture serves as a complex puzzle with designers crafting the right design story and the right experiences based on all the parameters of zoning, cost, schedule, site and more.

“Every step builds on the step you just took,” he says. “For us, seeing the changes is just part of our day. I think the challenge that we face is helping clients message the renderings appropriately.”

Whether a rendering was part of a competition to win a project or a visual early in the project, so many factors can cause a shift. Brown says that along with changing budgets, in-venue programming, site or zoning constraints, client design whims and more, even the age of a project can play a factor.

San Jose's stadium, before and after

“Technology can change. Design or aesthetic trends can change,” he says. “Over the lifespan of a project, the rendering or the conceptual design that a firm used to do a study in 2005 is barely relevant in 2016, even though the project is technically the same project.”

For the competition rendering, firms often have limited time, sometimes just weeks, to prepare a presentation.

“You are flying fast,” Brown says. “Lots of times the image generation will get started before the idea generation. In tight schedules or competitions, you have overlap and you have to navigate those waters.”

Sporting Kansas City's stadium, before and after

Brown says the success of a rendering isn’t so much in the final design matching the first rendering exactly, but in consistency throughout.

“The success stories are where the first thing that hits the press, gets presented, captures a big idea,” he says. “What are we selling, what makes it special? Maybe an entry piece or a roof form or a plaza design or something never been done with the seating bowl before. How much have those things changed? It is a great success if that big idea expressed in image one is still coherent and realized in the 10th iteration of the design.”

Tim Newcomb covers stadiums, sneakers and technology for Sports Illustrated. Follow him on Twitter at @tdnewcomb.