3-dimensional photography, otherwise known as 3D is a art style that strives to make 2-dimensional photography more detailed, informative and natural to the human eye. The goal of 3D photography is that when the viewer looks at the image, he or she will perceive it as though they were looking right at the object itself. You may be familiar with 3D film - the goal in 3D photography is virtually the same.
This type of photography can seem complex, but it comes easier once you've learned it. Initially, two photos are taken - one from one side of the object, and the second from the opposite side - showing the object of the image from different but equal points of view. The photos must be taken from the same view level, and about eye distance apart from one another. Once you have both photos, you can get an understanding for how the perspective should appear to the view, hold both photos side by side and cross your eyes. How the image appears is how you should mesh these two images to appear to the viewer.
The photos used to achieve the 3D images must be intensely clear and sharp. The two images should be almost the same - notwithstanding the small distance between subjects. Once the photographer changes the distances, that is how to the depth of the image is determined.