Web cam finder
The drawback of this of course is the addition of the weight of a second camera.This page describes how a mini laser pointer can be configured along with a single camera to provide mono-machine vision with range information.Below are two examples of the webcam based laser range finder in action.Note how it looks like there are two laser dots in the second example.A simple algorithm is run over the image looking for the brightest pixels.Assuming that the laser is the brightest area of the scene (which seems to be true for my dollar store laser pointer indoors), the dots position in the image frame is known.This project is greatly based on a tutorial found here The diagram below shows how projecting a laser dot onto a target that is in the field of view of a camera, the distance to that target may be calculated.
The dot from the laser is captured along with the rest of the scene by the camera.One specific improvement that can be made to this webcam based laser range finder is to project a horizontal line rather than a dot onto a target.This way, we could calculate the range for each column of the image rather than just one column.Then we need to calculate the range to the object based on where along the y axis of the image this laser dot falls.
The closer to the center of the image, the farther away the object is. To calibrate the system, we will collect a series of measurements where I know the range to the target, as well as the number of pixels the dot is from the center of the image each time.
I used a piece of cardboard to hold a laser pointer to a webcam so that the laser pointer points in a direction that is parallel to that of the camera.