Post Processing in Games

This week's blog will be covering the wonders of post processing. For this segment of my blog I will do a reel of photos from several different AAA titles and go over the different post processing effects applied in their games. So lets dive right into it shall we.

The first game title we are going to be looking at is Gears of War. The effect I'm going to focus on for this title is what is called bloom. Now, bloom is in simplest terms making the bright parts of the image brighter and the darker parts of the image darker. You would split the scene into two frames where one creates a blur effect, which I will talk about later, and the other is the original with amplified light to the bright areas. When this happens, you will see a light glow around characters that have high amounts of light behind them. This creates a high contrast and can set a certain mood in specific scenes in a game. Here in the image you can clearly see the use of bloom in game where the sky has been brightened and the foreground characters have been darkened and the glow is evident on the characters.

 

The next title we are going to look at is Assassin's Creed 3. In this image of the game we will examine the effect of depth of field. Depth of field is when the outside of the view of the cameras focus is blurred. So in the example below you can see that the people on the left hand side are very blurring because they are outside of the depth of field. This can be done by again using two frame buffers, one being your depth buffer and the other one being your blur buffer. 

Modern Warfare is a very widely known game for it's gameplay and graphics. They too implement post processing effects in their game such as motion blur. This effect causes the game to add extra sense of realism as this happens when someone is focusing in on one position. The image below is a good example of motion blur. The way how they create motion blur is when render a frame of the game to a frame buffer, down size it, then stretch it back to normal size, making the image very blurry, finally adding that image to the original scene. 

Now another shader and post processing effect we are going to discuss is cell shading or commonly known as toon shading. Now this non-photo realistic effect is partly a post processing effect because the black line drawn around the object is actually done after the graphics pipeline. This is done by a method of edge detection of an object. With edge detection, many other effects can be done. The shading of the object using cell shading is done based on a blocky gradient. Below is an image with the difference between normal shaders and toon shading. There is also an example of this effect in Borderlands.

Now for the next post processing effect, shadow mapping. This is a very important effect to give lots of depth and realism to a game. Although, many times it is faked in games, this is because computing shadows for the entirety of the game is very computationally expensive, some objects are dynamic and not static in which they need accurate shadows calculated for them. In the image below, you can see the dynamic shadow casted by the player while the shadows in the background are baked into the textures of the terrain. More commonly, one would see baked textures on walls in hallways that have many lights in them to save on computation.