Metheore is a spin-off of the University of Liege developing Machine Vision applications dedicated to raw material !

LaserSieve is an operational and innovating machine vision system that provides the size and the morphology of bulk rock fragments scrolling on a conveyor belt in harsh industrial environments such as quarries or mines. It improves the continuous production process providing these measures in real real-time. It has been conceived and implemented for the mineral industry in the framework of a sustainable development.


.The LaserSieve innovation is the use of 3D surface measurements. The scene is illuminated with a laser sheet of light. This creates a reflected line as seen from the light source, and appears as a curve from any other point out of the plane of the sheet. By observing the reflected sheet of light using high resolution camera and knowing the positions and orientations of both camera and light source, it is possible to determine the distance between the reflected points and the light source or the camera. By moving the scene (conveyor belt) a sequence of depth profiles of the scene can be generated and it can be represented as a range image. This on-the-edge technology allows us to acquire surface 3D images at high speed and thus keeping up with the industrial conveyor belt velocity.

We developed a perfectly optimized machine vision system (camera, lens and laser parameters combined) to obtain the best 3D images in terms of quality and spatial resolution. Calibrated images are free of distortion normally due to lens properties and perspective. This allowed us to measure directly real features in the image.

LaserSieve is able to:

  • analyse the conveyor belt running up to 3,2 meters/second,
  • take up to 30.000 profiles/second at 1536 pixels width,
  • take up to 7.000 profiles/second at 4096 pixels width,
  • accomodate a high resolution specialised camera device from 0,8 to 12,6 Mpixels,
  • get an accurate spatial resolution of 0,92mm/pixel at high speed conveyor belt (i.e. 3,2m/s).

Where a typical setup is:

  • 60cm of width at 1536 pixels (0,46mm/pixel),
  • 11,7cm of hight at 256 pixels (0,92mm/pixel),
  • 3,2m/s speed of a conveyor belt,
  • 3000 images/second shot