( Developed by José Francisco for his MSc thesis )

 Eye trackers can provide valuable information about the user reactions or interest even in Virtual Reality Systems. In these cases, and especially when head mounted displays (HMD) are in use the solution is to install the image capture setup inside the HMD itself.

In this article you can find the description of the construction of a low cost solution for the Oculus Rift DK2.


Augmented reality has recently received an enormous amount of attention from both general public but also commercial companies.

The game industry has been attentive to the long promised augmented reality, but technical difficulties have limited the achievable quality and this has postponed its inclusion in the offered games until recently. The increasing computational power of game consoles and the current awareness of general public to this type of technology makes impossible to ignore it at the risk of losing visibility to other competing companies that invest on it. 

One of the basic elements of AR, is the visualisation device. In most situations a modified HMD, that includes one or more front-facing cameras.

These HMDs, are typically composed by one or two LCD or OLED displays, sometimes a pair of earbuds or headphones, and an Inertial Measurement Unit (IMU).

The IMU can be composed by  accelerometers, gyros and magnetometers, being the latter only available in some models.

In most of current AR applications the interaction is limited to the motion of the handheld device or HMD as a way to change the point of view with respect to the scene that contains the virtual elements. We can say that for several cases this is sufficient if the objective is only the visualisation of those elements. What happens when the user wants to select different types of information or eventually interact with the virtual elements to modify their behaviour or even use them as control inputs for some physical system. The handheld approaches can make use of the touchable interface to select, open menus and select options of these elements. 

Conversely, the HMD-based applications are typically hands free approaches and selections or interactions must be made using buttons on the helmet itself, or using a gamepad or other handled device. We can say that there is more freedom for the interaction as the surrounding environment remains visible, keyboards, button pads, or any traditional device may be used.