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Posts Tagged ‘Left 4 Dead’

Raph Koster on Dynamic POIs

Monday, May 24th, 2010

Raph Koster, best known as the lead designer of Ultima Online and the creative director for Star Wars Galaxies, wrote an interesting post on his blog at the end of April. In the post, “Dynamic POIs“, He discusses how, in Star Wars Galaxies, they constructed a method for the computer to generate automatic content in the MMO world.

The term POI stands for point of interest and dates back to his UO days. At the time, those POIs were hand-placed by the design team. In a world the size of SWG, this was simply not feasible. He comments how even a room full of junior designers churning these encounters out was simply not enough. The proposed solution was to algorithmically generate these locations and fill them with life.

One of the complicating factors in this was that they weren’t simply placing the D&D staple of a wandering monster. They were generating a camp or facility full of these agents complete with scenery… and plot. Here’s a quote from the article that explains it better.

Don’t roll up just a bandit; roll up a little bandit campsite, with a tent, a campfire, three bandits, one of whom hates one of the others, a young bandit who isn’t actually a bad guy but has been sucked into the life because he has a young pregnant wife at home… In fact, maybe have an assortment of bandits — twenty possible ones maybe. Then pick three for your camp. That way you always get a flavorful but slightly different experience.

So what we are looking at is a random type of encounter with a random population, in a random location. So far that’s pretty groovy. If you want a description of what it was like, SWG producer, Haden Blackman writes about his own encounter with a dynamic POI.

One advantage that they had with SWG that didn’t exist with UO is that the SWG map was procedurally generated in the first place. That made generating a random encounter simply an extension that was over and above the map generation. They could create and destroy these places by simply making sure there was no one around.

…it was just as hard to create the dynamic content as it was to create static content.

In order to provide some variety, these encounters could also be designed modularly. The actors might be different or they may send you on different missions than a similarly constructed encounter elsewhere. The n-complexity of available encounters rises fairly quickly that way, of course.  Unfortunately, Raph says they weren’t quite able to make this whole process completely data-driven. The result is that it was just as hard to create the dynamic content as it was to create static content. In particular, the scripting of the encounters was tricky. The result of all of this is that dynamic POIs ended up coming back out of the game.

He hasn’t written off the entire idea yet, however. Neither have I. In fact, I spoke about it a little at GDC Austin in 2009. (Get my slides here.) Raph was not able to attend that lecture (for which I believe Sheri Graner Ray gave him a tongue-lashing). I don’t pretend to solve the problem of dynamic content to the extent that Raph writes about. The point I addressed was that there are ways for AI-controlled NPCs to dynamically deal with a shifting population and environment that can lead to more expressive encounters game-wide.

Anyway, with the advent of dynamic pacing in Left 4 Dead via the much-referenced AI Director, there is a lot more attention being paid to how we can break out of entirely hand-placed, hand-paced, and often linear content. Additionally, while the public’s appetite for “sandbox” worlds is increasing — thanks in no small part to games like GTA4, the industry can’t sustain GTA4-like budgets of $100 million for very long. If the procedural content issue was solved (or at least furthered along somewhat) then we can satisfy both the demands of our players and the restrictions of budget.

One place to look might be to the work that is being done by the likes of interactive fiction writer and programmer Emily Short and the work that is continually being done by Michael Mateas and the Expressive Intelligence Studio company and UCSC. Someplace in there is a hybrid of dynamic, data-driven storytelling that we can eventually work with to create truly open-ended content.

We can only hope… and work.

Interview on AIGameDev

Wednesday, April 15th, 2009

Back on April 5th, Alex Champandard of AIGameDev interviewed me for about 90 minutes for the Members portion of his site. Our topic was how to use behavioral mathematics (such as I cover in my book) to improve the bots in Left 4 Dead. We cover a lot of interesting information in the interview. Some of the examples refer to things I covered in my Post-Play’em columns on the AI in the game.

He has it posted in audio and video formats (although with me rocking back and forth in my office chair, I look like I’m autistic!). I seriously advise that you check it out. (You will need to have access to the members area to view it.) If you are already a member of AIGameDev, you can find the interview here:

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