The 3 motion technologies compared

Sony / How does it work? Sony have not been very forthcoming about how their controller works, but it seems fairly straightforward. Despite the obvious visual difference to the Wii Remote (primarily due the light source on its tip), the technology inside PS3’s motion controller is likely similar to the accelerometer and gyro in Nintendo’s controller. The PlayStation Eye’s raw specs strongly suggest that by itself, it cannot be used to track the controller accurately enough for motion controlled games. The Eye’s camera has a maximum resolution of 640×480 – not nearly enough to track the light source with the sub mm accuracy that was demonstrated so effectively on stage. This is especially true when sitting at the typical viewing distances 44″+ tvs require, and gets worse as distance increases. Also, the Eye’s highest resolution limits it to 60fps, which is not fast enough to track regular motions, let alone fast ones. The combination of the controller’s easily identifiable light source and the Eye are likely primarily used to place objects in the player’s hand in realtime on the screen, and also to track the controller at a coarse level to supplement the data sent by the accelerometer and gyro.

A revealing moment was the bow and arrow demo – particularly when the arrows were being pulled from behind the demonstrator’s back. The controller’s light would not have been visible to the PlayStation Eye at that point (it was occluded), but the system was still able to track the controller and update the webcam feed without a hitch – a sign that the sensors inside the controller are the main way it tracks motion and that they work largely independently of the Eye. All in all Sony’s solution to motion control appears very elegant, and with the PlayStation Eye it has some significant advantages over Wii MotionPlus. Things holding it back are the lack of a Nunchuk equivalent and perhaps a lack of resolution for pointer based games.

+ Extremely accurate and very reliable if accelerometers and gyros are being used.
+ Due to it sharing many similarities to MotionPlus, the ability to make cross-platform games will mean the peripheral has a better chance of 3rd party support.
+ With the light source and the PlayStation Eye, the system can capture the gamer and put him in the game. MotionPlus cannot do this, and even if the DSi’s camera were used, the Wii Remote has no distinctive light source to make it easy to track.
+ The analogue trigger adds a degree of sophistication over the plain Wii Remote and MotionPlus combination.

– The controller looks like a Fisher Price designed sex toy – not exactly a match for aesthetics of the PS3 and its peripherals (u: though yes, this is not the final design).
– At this point in time, it doesn’t have access to an analogue stick – a limiting factor when it comes to traditional games.
– The controller seems to have been designed to compete directly with Nintendo’s technology, whereas Microsoft’s solution appears more radical and innovative.
– Another thing that traditional games benefit from is a pointer, something that will be tricky with Sony’s new controller. Essentially Sony have reversed the setup of the Wii – the camera is placed near the tv, and the light source is on the controller. The disadvantage of this is that the camera does not have enough resolution to track the light as a pointer, unless the player makes large movements. This is because when pointing on the Wii, the player pivots the camera which radically alters the position of the sensor bar in its field of view. On the PS3 however, players will be pivoting the light source which will alter its position relative to the Eye very little, meaning the PS3 will have very little spatial resolution for a pointer if used in this way. A good example of this is the famous Johnny Chung Lee headtracking demo, where he taped the sensor bar to his head and used the Wii Remote as a static camera.

The equivalent of a pointer will have to be tracked through the gyro and the accelerometer, which is not as straightforward as the Wii’s IR setup. This is why Sony went to such great lengths to demonstrate the sub mm accuracy of the controller – because it has no equivalent of the Wii’s IR pointer. Can the crosshair in a traditional FPS games be controlled accurately enough this way? Or will drift errors mean the player will have to calibrate the controller often so that the crosshair can remain in the right position? Only time will tell.