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AR Bridge Builder

This was a student project I worked on together with two fellow students while studying at the University of Canterbury, New Zealand. Published as a paper at the IVCNZ07 and received the award for the best oral student presentation.

Publication (Paper):

AR Bridge Builder: Real-time Vectorisation of Freehand Sketched Structures for an AR Application
Proceedings of Image and Vision Computing New Zealand 2007
Frank Petzold, Jonas Pfeil, Christian Riechert and Richard Green
Paper - Talk Slides - Hide BibTex


  author = {Petzold, Frank and Pfeil, Jonas and Riechert, Christian and Green, Richard},
  title = {AR Bridge Builder: Real-Time Vectorisation of Freehand Sketched Structures for an AR Application},
  booktitle = {Image and Vision Computing New Zealand 2007},
  year = {2007},
  location = {Hamilton, New Zealand},
  pages = {192--197},


AR Bridge Builder is an augmented reality version of the game Bridge Builder where the goal is to get a train safely across a river or valley.

The bridge is drawn on a whiteboard (blue for trusses and red for anchor points). Our computer vision algorithm recognizes the bridge and tracks it over time. The resulting model is simulated using PhysX and overlaid over the camera image on the laptop monitor. Tension and pressure on the trusses are visualized using shades of blue and red, respectively.

When starting the game the user has to point the camera straight at the whiteboard which initializes a reference coordinate system where we assume the image plane is parallel to the whiteboard. After that the user can move the camera and the simulated bridge is drawn perspectively correct. This works because all the points of the bridge lie on a flat surface, enabling us to compute a homography.

C++, OpenCV, PhysX
Frank Petzold
Jonas Pfeil
Christian Riechert
Prof. M. Billinghurst
Dr. R. Green