GT4, AI, and other numbers

Saturday, July 23rd, 2005

Over these past few months I’ve been tinkering with Gran Turismo 4, the latest version of Polyphony Digital’s “Real Driving Simulator.” This version represents an improvement over the A-spec release in two ways: the physics engine and the Artificial Intelligence engine. In GT4, opponents are smarter and tougher. In terms of physics, you never really got a sense of environmental elements in GT3, such as elevation and surface, but in GT4, elevation can be dizzying and road surfaces really jog the undercarriage and if you get bogged down in the sand, you’re basically sunk.

In terms of the simulator’s AI, improvements have been made, but there are still major stumbling blocks. For example, in the GT All Stars race, in the Extreme Race category, you’re up against the hottest cars the game can muster. You can choose two participation modes: A-spec, where you drive, and B-spec, where you coach “your” AI driver through a race against the other AI drivers. In B-spec mode, my driver is fairly dense, even though I’ve accumulated quite a bit of points in this mode, which amount to adjustment variables which define AI experience. B-spec mode is interesting; it gets you through very long races. But in shorter, intense goes, the driver makes silly mistakes (and you can’t tell it not to, which I hope would be covered in GT5). On the other hand, I typically take care of the competition handily in A-spec mode, not because my car is incredible (it is, though), but because I don’t drive the way the game expects me to. My style is to muscle the car around corners and slide it quickly into the turns and to use horsepower to get it back on course. So, GT4 appears to set up a human vs. machine intelligence factor.

Case in point. In the positively scary Autumn Ring course, AI cars appear to take one turn at the wrong angle habitually. It’s not speed that’s the problem, it’s the line the cars choose to take at that speed. Autumn Ring climbs quickly, turns quickly, weaves, and hot cars can take the course at high speeds. I run the race myself, hit that dangerous curve, and can easily see why a driver would run off the road (I did it a lot). But, next time around, I adjust my line and take better care. In B-spec mode, my driver won’t make the adjustment; he continually zooms off the road and struggles to get back into the game (but so do a lot of the other bots). Hense, he’s dumb. It may be that as I acquire more B-spec points, the AI will adjust better. But for me, this isn’t the issue: the issue is the machine’s ability to make decisions “during” a race and my ability to charm it to do so. In this sense, the manager mode in GT4 still needs improvement at both the calculation and interface level.

GT4 is amazing, really. A-spec mode is still my favorite way to go. But given the physics engine and the cranking up of the speed factor, which really taxes my ability to react at 200 mp with a real sense of jolt, B-spec is a fantastic idea.

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