Robotics and Computer Vision
computer-vision, robotics
Solution
It's best to bypass elaborate vision software altogether and use simple electronics. There are devices called phototransistors which are sensitive to light. Point two downwards at each side of the robot, shadowed from light from above. If the bot starts to go right instead of following the line, the left sensor will be activated. If it goes left, the right one will be activated. Use the feedback of these signals to guide the robot (you could possibly apply them almost directly to the motors if you have two motors).
Problem
Couple of friends and i will be building simple robot to track a white line on a black surface, we have never done this sort of thing before and i have very high level plan of attack, Get a mini atx board for all computing needs, a web cam to track the road and 2 electric motors one for propulsion one for direction. My main concern is, is there a better way to track the road? or does a webcam work for the job? EDIT: Follow up on the answers using Photoresistor seems to be the way to go, bu i have one more question there will be signals, to the right of the track telling the robot which way to turn. again white on black. such as i have to make a left on a t-junction. is there a way to handle this without a camera?