A Design Methodology for Selection and Placement of Sensors in Multimedia Surveillance Systems

 

Aim

Designing to reduce cost for specified performance

 

Approach

  1. Define a performance metric (η)
  2. Find all combinations s.t. η > required performance (σ)
  3. Choose the combination with least cost

We define η as the average probability of capturing the frontal part of a symmetric object at a particular time instant

 

 

Results overview

      We found that 2 cameras in a square region should be placed at diagonals. Center is not always the best choice.

      Similar (though not same) results were found in irregular areas. The basic idea remains to get the cameras to cover maximum possible area independently while minimizing their commonly focused area.

      The sensor performance saturates at certain points. e.g. We found that adding more sensors beyond 12 or increasing the camera field-of-view above 45 degree did not increase the performance anymore in the studied setup. Hence, we can find such threshold values and ensure that we do not spend money on enhancing the sensors beyond these values.

      Actual tracking results corroborated well with the theoretical optimal camera placement positions. Tracking provided 69% frames with frontal face information when cameras were placed at the diagonals.

      Use of motion sensors helped in recovering from situations where the object was lost. e.g. From (g) to (h) in figure below. Hence motion sensors can help in improving the performance.

Text Box: Camera2Text Box: Camera1

Publication

Siva Rama K. G., Kalpathi Ramakrishnan, Pradeep K. Atrey, Vivek K. Singh and Mohan S. Kankanhalli. . A design methodology for selection and placement of sensors in multimedia surveillance systems. The 4th ACM International Workshop on Video Surveillance and Sensor Networks in conjunction with ACM Multimedia 2006 (ACM VSSN'06), October 27, 2006, Santa Barbara, California, USA. (To appear)