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# GPS Pacman

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"Augmented Reality quake"
http://wearables.unisa.edu.au/projects.php

Pacman would be cool, the only problem is this:

GPS is only updated once a second
and GPS can be off as much as 15 feet,

unless you have military connections....

It would be better to place sensors around you''re playing feild is, and trianglulate your position from them...

I assume thats what the MIT students did...

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I know MIT did it but I''m trying to do it on an unfunded amature budget. 1 second isn''t too bad. Interpolation would just have to be pretty good.

If done properly as technology improves all you''d have to do is plug it in and maybe add in a method to interpret the data for the new GPS device.

darksmile.net port 12321 is feeding out live GPS data making it possible to experiment without buying a GPS device initially.

If I ever have time this is definitly something I want to try. The only things I don''t have are a GPS ($100) and a web-cam (tend to be free with rebates). Both of which are cool toys even if making a game out of them fails. Ben IcarusIndie.com [ The Labyrinth | DevZone | The Wall | Hosting | Tiberian Merchandise | GameShot | Fun With Cutouts ] #### Share this post ##### Link to post ##### Share on other sites http://www.3dfex.com/ here is glasses for under$100 dollars...

you can find others searching google, and since they are compatible with may 3d games, they are rather cool...

No, interpolation won''t help you, since at one point, GPS could position you anywhere in a 15 foot radius... so you could theoreticlly jump around and still stand in one place, this limitation won''t change, since its a military downgrade.

If I were doing your project, I would find an open field, and then place 3 radio transmitters...
You could then detect their stength...and that would be your location...

Doing so would prolly be cheaper than a GPS, as long as you look for used parts...

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I created a simple app to read and interpret the location/velocity data streaming off of darksmile.net

He was kind enough to provide a slightly convoluted rendition of the interpreter in Perl although not nice enough to leave it running so I could check my answers when I coverted the parts I needed to a C++ class. According to a fixed page I''m off by 4 degrees which is about 440km. Maybe he''s moved recently.

Anyway, apparently it''s stationary because I''m getting the exact same coordinates down to the 15th decimal place so I don''t think jerking around is going to be too much of an issue. At least once you stop moving.

Radio transmitters would be neat but I''m going for the ability to run around a very large university campus playing Pacman. I''m going to see how well a GPS will work since on that scale it''s significantly cheaper. I can always change the position inputs later.

Next step, the web-cam.

Ben

IcarusIndie.com [ The Labyrinth | DevZone | The Wall | Hosting | Tiberian Merchandise | GameShot | Fun With Cutouts ]

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With a 15 foot (5 meters) / 1 second resolution, you''d need pretty good image recognition software to get enough data to interpolate accurately. A human being takes up about 2 square feet (around a quarter of a square meter) of floor space standing still. For most purposes, a meter square grid will be about right for treating people as game pieces, so you can only position your player to being in a 25 square area (OK, only about 20 squares worth of area actually falls within the 5 meter radius circle) At full sprint, an average human gets close to 10 meters per second, so the player''s location can change up to 10 squares between position updates. Acceleration, I don''t have data on handy, but a rough estimate would be that I can change from about 2 meters per second in one direction to the same in the opposite direction pretty much instantly, so certainly within a second (if I did and took one second to do so, then the interpolated position would be 2 meters out by the end of the second, and that''s assuming my speed was known accurately at the beginning of the second...) Or if I''m sprinting at 10 meters per second and run into something I can pretty much stop dead in negligible time, meaning that by the next position update, I could be up to 10 meters different from my extrapolated position.

Of course, the 15 foot inaccuracy in position data is only a problem if the error varies randomly across relatively small regions in short time periods. I suspect in practice, the variation is sufficiently smooth that change in location would be accurate enough. On the other hand, the slow sample rate compared to human accelerations could make the game unplayably sluggish and/or jerky depending on how display updates are extrapolated between samples. (Technical nitpick - you can''t interpolate on the fly for this sort of data because you don''t know what the next accurate data is going to be until after you need to have displayed the frames you''re attempting to calculate)

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Actually, some guys at U of PEI are working on a system like GPS quake, but slightly different. Instead of using GPS, the helmets contain a system for tracking relative movement.

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I don''t have much to add, but I think that''s a really good idea.

Will

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