FIFA 10: Rendering Depth of Field

 Michael Day, Art Director

As we get toward the end of this development cycle on FIFA 10, we’ve been busy taking screen shots of the game for marketing. As some of you may, or may not have noticed in previous years, many of the screen shots would include depth of field. Depth of field is an artefact of lens optics in video and still cameras, where objects not in the focus plane appear blurry. As the camera operator opens the aperture of the lens to let more light onto the light sensitive film, or sensor, the narrower the depth of field, (or blurrier the objects not in the focus plane).

Typically this is done to allow longer focal length lens (zoom lenses), and allow faster shutter speeds, which let the image taker get closer, and freeze fast actions. Without fast shutter speeds, we would see another common artefact of photography, motion blur. Sports photographers, and video camera operators need both long, and fast lenses to capture close up action on the pitch. While depth of field can be considered an artefact of photography, it is something we are very accustomed to seeing in images. Depth of field can also be used to focus the image viewer on the intent of the shot, by blurring out the stuff that isn’t important.

Since we are so accustomed to seeing depth of field in images, it’s important to add it to our renders, and game, to make them look realer. The rendering engines in previous versions of FIFA have been able to render depth of field to some degree. However due to artifacts, performance, and the lack of logic to drive it, depth of field was minimized, and reserved for still image capture from the game. In FIFA 10 we have had the opportunity to put a little more focus into Depth of field. In previous versions of FIFA, the depth of field was driven by an artist setting a series of depth based planes. For example, the distance at which objects would be in focus, the distance at which objects would be blurred, and the maximum blur amount. Blurring would then be applied linearly between the two distances, to the maximum amount. This of course will not look real, if not set carefully by someone will photography experience, and even then, the linear nature of the blur interpolation is not physically correct. On FIFA 10 the rendering team implemented a new physically based depth of field calculation that better simulates what happens in real lenses. With more logic for targeting players, and better artist driven camera controls, we have created a depth of field effect that not only looks good in marketing screenshots, but also looks good in game.

There are important considerations that need to be made when assimilating elements of photography, and video broadcast into a video game. For instance, you wouldn’t want a game play camera to be blurring out potential pass recipients. Careful consideration has been applied to where and how much depth of field occurs in the game, so you’ll see the depth of field effects in non interactive sequences, replays, and highlights, without the effect interfering in game play cameras. One camera where the gamer can experiment with the depth of field effect is the Instant Replay Orbit camera. A new control has been added to the interface to allow gamers to not only dolly the camera closer/farther from the player by moving the left stick up/down, but also to zoom in/out by moving the left stick left/right. This means you can frame a player with a wide angle, close up shot, which has relatively deep depth of field (less blurring), or you can zoom in from a distance, creating maximum bokeh effect.

Depth of field, along with other rendering, art, and front end graphics are there to help support and enhance the great game play and game modes, by presenting them in the most realistic way possible. Hopefully, the depth of field effect will not be the first thing gamers notice when they play FIFA 10, and that it is just one more element that allows gamers to feel they are immersed in the most authentic football game possible.