Monday, April 29, 2013

Pre-Render Vs. Real Time Graphics

There’s a lot of different types of digital art. In terms of 3d, you’ll see two main types, pre-rendered and real time.

Let’s start with some definitions.

Real-time is when a computer can render the graphics on the fly.

Pre-rendered is the opposite. The computer cannot just render the graphics quickly and easily, it usually takes time, so it is render “previously” by another really powerful computer/computers.

And a side not: Rendering is like drawing, except the computer does it.

So what’s the big difference? Pre-rendered takes a lot more resources, so the payout is much better yielding better visuals. Pre-rendered graphics have always been more advanced for years. For example let’s look at Pixar’s “A Bug’s Life.” This was from 1998! Compare that to the graphics of a critically acclaimed video game from 1998, Konami’s Metal Gear Solid. Huge difference!

Pixar’s A Bug’s Life, 1998 pre-rendered material

Konami’s Metal Gear Solid, 1998, real-time visuals.

Studios like Pixar have huge rooms devoted just to rendering, filled with several computers. A company like Pixar can have hundreds of computers running. Smaller companies, like the Blender Foundation, when rendering Sintel, had maybe 30 computers running. The AC was cranked, and the room was still really hot, with all the heat being generated from the computers.

What about today though?

In Bioware’s latest installment in the Mass Effect trilogy (part 3) they released some pre-rendered material to help advertise the game.

Here we compare Commander Shepard, pre-rendered from the trailer, and rendered in real time from the game. It’s a huge difference compared to the 1998 example of Konami‘s Metal Gear Solid vs A Bug’s Life. However, you can still clearly see which is the visual king.

On the left, a pre-rendered version of Mass Effect 3′s main character Commander Shepard, on the right a real-time version.

Generally real-time graphics aren’t as good. They feature low poly models without all the bells and whistles that pre-rendered visuals can achieve. That’s because a computer has to be able to render the graphics on the fly. Pre-rendered visuals feature better lighting, shading effects and high poly models. The computer has to do a lot of advanced math and calculus to determine proper light paths that simulate real life. The end output is a video file, that can be played anytime, but took hours (usually hundreds) to render out.

The each serve a difference purpose. Generally real-time graphics are reserved for interactive media, such as video games. Pre-rendered graphics are used in the movie industry and game industry. Most movies include some level of pre-rendered visuals, whether it be a backdrop or added effects.

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