Star Ocean 5 is the upcoming major release from Tri-Ace, who recently attended SIGGRAPH 2015 to talk about their rendering techniques in detail. In one of their presentation, Tri-Ace revealed the basic implementation of Bokeh depth-of-field effect in their engine. This also included a short segment related to its implementation in Star Ocean 5.
Tri-Ace begins the presentation by explaining that their are two ways to implement of Bokeh depth-of-field effect: Scatter and Gather. Scatter looks better and is theoretically easier to implement, but it has an impact on performance. Gather is usually good for performance and hence it is recommended for older hardware.
The usage of Bokeh depth-of-field with an optimal performance requires many hacks to be utilized. A larger Bokeh depth-of-field will require many taps resulting in an increase in computational power. Tri-Ace recommends using lower-quality texture for a larger Bokeh.
Tri-Ace then gives an example of the performance impact of using more taps for Bokeh for their engine running in real-time at 1080p on the PS4. You can see that as the taps count increase, the rendering latency also increases starting with 1.9 ms with 58 taps to 3.2 ms with 130 taps.
In another interesting comparison, the developer shows this Bokeh effect running at 720p on PS3 and 1080p on PS4 along with the performance it carries on both platforms. This also shows the performance of their engine on PS3 vs. PS4 for Star Ocean 5, as the game currently runs at 1080p/60 fps on the PS4 and 720p/30 fps on the PS3.
For their Bokeh depth-of-field implemention, Tri-Ace also utilizes a technique called Focus Breathing. This technique adjusts the focus distance based on the field of view and exposure. Check it out in action below.
Finally you can see Star Ocean 5 utilizing this Bokeh depth-of-field effect on the PS4 in the screenshots below. It is currently set for a release in 2016 for the PS4 in the West while it will be released on the PS3 and PS4 in Japan this year.
It is rather interesting to see the developers revealing their techniques that we see in action in their games. Star Ocean 5 has a very unique art style that definitely fits the look of Tri-Ace’s in-house engine.
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