Why You Need Lasers
Lasers provide a visual reference to objects underwater. It is difficult to determine the scale of a subject without a frame of reference.
Think of a laser as an underwater ruler, painted on the scene. Lasers can also help measure or estimate distance to subject.
Parallel Dots
A parallel dot laser projects two beams, appearing as green dots in images, and is used to get distance and scale of underwater objects. Usually parallel dots are the lowest cost form of laser. They are attached to a camera so that the dots are parallel with the frame of reference.
Line Laser
Line lasers are used for precision applications for generating data from images. Often the data is for creating a 3D model or point cloud.
Grid Laser
A grid laser projects hundreds of points onto the scene. This gives multiple redundant data points that allow for more complex geometry. The points spread out at a predictable angle from the laser.