Motion Sensing and the Camera Trap

The PIR Sensor:

'A Passive InfraRed Senor measures infrared (IR) light radiating from objects in its field of view. PIR sensors are often used in the construction of PIR-based motion detectors. Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall.[1]

All objects emit what is known as black body radiation. It ilios usually infrared radiation that is invisible to the human eye but can be detected by electronic devices designed for such a purpose. The term passive in this instance means that the PIR device does not emit an infrared beam but merely passively accepts incoming infrared radiation.' -Wikipedia's definition

Pros:

  • The PIR uses very little electricity, which is great for the camera trap scenario.
  • It does not emit IR light.
  • Wide "angle of view"
  • This one is highly controllable: ePIR

Cons:

  • PIR doesn't give any information about the location or quality of movement in the scene.
  • Flickering leaves and other incidental movement in the scene give many false positives.

Rethinking the Sensor:

Photo Sensor Matrix

Little computers capable of doing live image processing:

  • Android Phone
  • Beagle Board
  • GumstiX

Links for Android imaging; Working with Images in Google's Android Jon's Java Imaging Library Android Forums vOIce Assistive Tech for Android

the model: Mini Computer for Live Image Processing

How much info can be contained in a photograph

  • Laser assisted measurements for 2D (2-point laser assist)
  • Laser assisted measurements for 3D (projected laser line + simple trigonometry)
  • How helpful is a 3D image map?
  • Image quality is highly important not only for general clarity of the photo, but also for laser measurements.