He adjective three-dimensional It is used to qualify that which has three dimensions . To understand what the notion refers to, therefore, it is necessary to understand the concept of dimension .
In the context of the physical and of the geometry , the idea of dimension refers to the smallest amount of coordinates that are needed to locate a point. A line, in this sense, is one-dimensional : reaches with a coordinate to locate any point of it. The plans, however, have two dimensions since it is essential to know the longitude and latitude for the location of a point.
Following the same reasoning, the three-dimensional objects demand the knowledge of three coordinates to find a point inside. It is often said that the space around us is three-dimensional, although there are more dimensions (there are those who include time as one dimension, for example).
Broadly speaking, it can be noted that in a three-dimensional space The height (or depth), length and width are present. Knowing these three coordinates, it is possible to locate a point in the space .
Currently, three-dimensionality usually appears as an effect or a phenomenon produced by two-dimensional objects, such as a television screen. In these cases, the three-dimensional is a simulation which is achieved from the projection of certain data. A person who uses the corresponding glasses in a movie theater and watches the projection of a 3D movie can "feel" that the action takes place in a three-dimensional space and not on a screen, since the images seem to project in three dimensions.
This type of three-dimensional effect is often called stereoscopic , since it is achieved through the projection of two simultaneous images, one for each eye, each from one perspective slightly different. In other words, although for many, 3D is nothing more than a fashion for filmmakers and video game developers, it manages to make content on the screen less abstract, since it represents it in a way much closer to what our eyes perceive in reality.
Of course, not everyone can enjoy the three-dimensional content: on the one hand there are people who have lost an eye or have certain health problems that prevent them from correctly perceiving the depth ; on the other, this effect causes some headaches, especially after several hours of exposure. These inconveniences make it difficult to massify 3D as a basic form of projection of audiovisual content, but this does not prevent it from gaining more and more strength in the market.
Given the new awakening of stereoscopic 3D (let's not forget that its origins date back more than a century ago, when in 1833 a British physicist named Charles Wheatstone created the "Mirrorscope" to visualize images in three dimensions), the public began to have difficulties in understanding the meaning of the term "three-dimensional", since until then it was limited almost exclusively to the environment of computer-generated graphics, such as those used for films of Pixar .
In the field of video game , the three dimensions became the norm in the mid-90s, largely thanks to the success of consoles such as the Nintendo 64, the Playstation and the Dreamcast. However, the experiences of a three-dimensional game are very different from what a two-dimensional one can offer; Therefore, after "the 3D fever" two-dimensional games reappeared, and today there is a greater variety in the market.
As a curious fact, today is normal use three-dimensional graphics to create two-dimensional content , since it is enough to use a projection orthogonal to cancel the perspective (if the camera does not perceive the deformation of the objects along the Z axis, then the sensation of depth disappears, even if we are visualizing a three-dimensional model).