VAMPIRE___Visual Active Memory Processes and Interactive REtrieval
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Intro Research Activities Scenario 'Mobile augmented reality' Scenario 'video annotations' Slideshow
object recognition and learningvisual trackingaction recognitionAR gearself localisationscene analysis
contextual analysisinteraction and augmented realitysystem integration

Hardware concept & description

A mobile augmented reality system usually consists of components recovering the user's position and direction of view such as GPS, RFID tag reader, vision-based tracking or inertial tracking devices, and a possibility for the visualisation of information - usually a head mounted display (HMD). Besides, a human computer interface (HCI) is commonly used for the communication with the system providing the augmented information, for instance the personal interaction panels or pinch gloves.

We have setup a custom video-see through system based on two firewire webcams, an HMD, and a laptop which is used to render information and to serve the HMD with the stereo video stream. A custom CMOS camera and an inertial tracker are used for hybrid tracking which is run on a single board computer (SBC). A mouse (buttons only) is used as user interface. Laptop and SBC are mounted on a backpack and are connected via LAN (direct link). HMD and tracking sensors are mounted on a helmet. Wireless LAN can be used for communication between several mobile AR-kits (multiuser AR).


Visualisation subsystem

The laptop applied for visualisation has an OpenGL graphic chip (nVidia Quadro 500 GoGL) which allows for hardware supplied stereo rendering of the graphics for the custom stereo video see-through head mounted display (HMD) consisting of low cost, off-the-shelf components such as two Fire-i firewire webcams and an I-visor 4400VPD HMD.

Tracking subsystem

A custom mobile PC system has been assembled for hybrid tracking, as laptops seemed to be not flexible enough to allow for experiments with various hardware for tracking e.g. PCI extensions for frame grabbers. The system basically consists of a single board computer and a power supply (AC/DC) which also serves all the peripheral hardware of the mobile AR system such as HMD, firewire cameras, CMOS camera and inertial sensor. This hardware is mainly used for self-localisation or inside-out tracking.

Hardware concept and snapshot of mobile AR-gear

I:NEX Camera

We implemented a custom Fuga 1000 based CMOS camera I:NEX with USB2 interface to gain extremely fast access of small, arbitrarily positioned image portions typically used for tracking of corners or other local features with small support regions. For instance, image acquisition for vision-based tracking of the artificial target, which requires 7 windows of size 32 x 32 pixels, can be done at 700 Hz (requests per second). This vision-based tracking is fused with a commercially available inertial sensor by Kalman filtering to deal with fast rotations of the head.

Selected Publications