Perspective Dependent Instantaneous Path Recognizer
Vishwa Manoharan, Prashanth Boovaragavan · 2011
Visually impaired people rely on external devices for navigational purposes. Perspective Dependent Instantaneous Path Recognizer (PDIPR) is a modified mobile phone capable of path recognition. The path in front is captured by Range Imaging using the Time of Flight (ToF) principle. This involves an active illumination source which is an LED bulb attached to the mobile near the sensor. Once the image has been taken, the colour intensity values are not recorded on the image, instead the distance values are directly recorded onto each pixel. This is possible by calibrating it in such a way that the shorter the distance, the higher will be the 8-bit grey scale value of the pixel. The image is taken in such a perspective that the distance from the camera to a point on a flat ground will gradually increase, as the point on the ground moves farther away from the person. Two Standard-Pixel DifferenceMaps (PDMs) are developed from this flat path by computing the difference between every adjacent pixel in the vertical columns and horizontal rows. Now the path in front is captured and the Vertical–PDM and Horizontal–PDM are developed from it.If the path is not flat, the gradual increase in distance (i.e. the gradual decrease in pixel value) from bottom to top of the image will not happen. By our pixel difference analysis method any deviations ofpixel difference in the Vertical-PDM or Horizontal-PDM of the new image from the Standard Vertical-PDM or Standard Horizontal-PDM can be studied and the path in front can beinferred as a traversable path such as a slope or stairs or as a non-traversable path with obstacles in it. Both static and moving obstacles are recognised by this method. The appropriate warning can be conveyed to the user via vibrations or audio outputs in real time. Assisted-GPS with voice recognition helps to navigate from one place to another. Combined together, PDIPR proves to be a first of its kind, handheld and affordable solution for safe navigation of blind individuals in the open world.