David Marr (1945-1980), British neuroscientist and physiologist, developed one of the most known theories about the way our vision works. According to him, we receive an input in a similar way to an image in our retina, and this will then be processed by our brain in three different steps.
When you first receive an image of an object, your retina makes a simple register of the light intensity in each point of said image. That’s when you start detecting the vertices, the boundaries between objects, shapes, spots of union… Resuming, you get the fundamental points of the object, but not the depth or textures yet. This primal sketch is totally dependent on which perspective the object is presented to you at.
The 2.5D Sketch
The second step is still dependent on the perspective in which the object is presented to you at, yet, now you have more information to work with, such as the textures as well as depth and you can start to see how the visible surfaces of said object relate to each another.
In this last step, you’ll be able to get the information which is not dependant on the perspective. These representations are built from the visual inputs and compared with the representations stored in your Long-term Memory. At this point is where object recognition will take place.
Marr’s theory is able to tie together the initial vision and the eventual object recognition, providing us a theory that can explain the whole system of recognition and identification of objects and patterns visually presented to us.