How can 3D maps be made with ordinary photographs? by Adam Steer

An ordinary photograph is really a two-dimensional model of a three-dimensional world. We can also reverse the process - and figure out where an object in an ordinary photograph was positioned in the real world.

To do this we need to know a few things about the camera - we need to know how it made the two-dimensional model.

If we know about the camera and have two or more photographs that overlap, we use the camera information, image properties and matching objects in each photograph to figure out where each camera, matching object and potentially every pixel is in three-dimensional space.

So it is a big circle! A camera makes a two dimensional model out of three dimensional things. These two-dimensional models can then be combined to reconstruct a three dimensional model – which can be used for surveying tasks which are not so easy with the ‘real’ things.

Adam Steer