# What Is 3D?

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Many new MODO users may have downloaded and installed our software with little or no background in 3D graphics, much less 3D at all. This section is meant as a basic primer for those interested in 3D graphics but with very little background or understanding on the subject overall. While not a complete definition by any stretch of the imagination, it has been stated as plainly and as simply as possible, providing new users with a basic introduction into the terminology many of us take for granted.

So what is this 3D stuff all about anyway?

3D seems to be the hot buzzword these days. Everything has got to be "3D", but what does "3D" mean really? Well, actually, it can mean multiple things; so first let's define what differentiates 3D from 2D by defining what "2D" actually is. A great example of this would be what you are presently looking at, your computer monitor (right?). Despite how things may look, your screen is a strictly two dimensional or "2D" surface, a flat plane. It has millions of tiny colored squares on it called pixels (for Picture Elements). They lay across it horizontally and vertically in a grid formation. These two dimensions (horizontal and vertical) could be labeled as X and Y, respectively, as reference to geometry (the mathematical kind). With them, you can pinpoint any position on the screen by simply using two values, one represented by X, the left and right direction, and one for Y, the up and down direction. But, there is no "in-front-of" or "behind", it's just a smooth, flat surface all the way across. By adding one more dimension to that flat surface "Depth", suddenly everything changes. This depth, designated with the addition of a Z value added to the previous X and Y, can now pinpoint any location in space; you're no longer confined to the single plane, this is where 2D becomes 3D. If your monitor had all three dimensions, it would suddenly be possible to have a real 'in-front-of' and a 'behind' (as it likely will be one day, but alas, not quite yet) . This makes perfect sense because human vision is designed for "3D", our two eyes provide two slightly different views of the world that our brains then put together to provide our sense of depth. So the simplest definition of 3D is any medium or technology that introduces 'depth'.

INFO: In geometry, this system of defining positions in X,Y and Z space is known as Cartesian Coordinates named after its inventor, Rene Descartes, who was also known as 'Cartesius'. He was a 17th century mathematician, physicist and philosopher famous for saying "I think, therefore I am".

How did depth become a buzzword?

The term "3D" is still fairly broad, there are multiple different, yet oddly common meanings to the term (that seem to be used interchangeably, and often incorrectly); two in particular relate directly to what MODO does.

The first and most common is in the form of 3D stereoscopic images, a means of coaxing 3D depth from 2D images. Often referred to as '3D' when it is really called "Stereoscopy". The technique was initially introduced in the late 19th century (at the dawn of photography), the stereoscope (seen here on the right) was a early technology where two images, photographed slightly apart from each other, and observed through the viewer, produced a sense of 3D depth. The very same technique popularized by the View-Master system you likely had as a small child that is still captivating kids today. There have been other variations to the technology as well, such as overlaying the two images and then filtering how our eyes see them with glasses, referred to as 'Anaglyphic Stereo', many comic books and B-movies of the 1950s popularized this technique with their iconic red and blue paper glasses. Modern 3D cinema also combines two separate images (using two projectors aligned over the top of one another) onto the same screen that when, same as before, are filtered with glasses, but now they are 'polarized', a technique that capitalizes on the wavelength property of light. When done well it produces a 3D image with all the depth and color of the world around us.

MODO is capable of generating imagery very easily that can be used for these purposes, but there are no viewers or hardware one can use or purchase that displays the depth directly within MODO itself. Users would need other external tools to combine images generated by MODO to produce the final stereoscopic result.

MODO and modern era 3D

The next most common meaning to the term "3D" (and the one we are actually most interested in), is in relation to images that are generated virtually, that is to say generated by means of using computers graphics software; think movies like 'Toy Story'. All 3D programs (like MODO) utilize a method in which objects are modeled by defining their shape mathematically. In most cases, these virtual objects are defined using the previously mentioned X, Y and Z coordinates system, this is precisely what makes them 3D and why they are called such.

Let's explain it a little more. For simplicitie's sake, say you wanted to model a three dimensional cube, this is done by defining the coordinates of the eight corners, each would receive its own X,Y & Z value, designating their position in space. Each position is referred to as a 'vertex' (plural: vertices); they have no size or volume by themselves, they are simply positions. Now, additional instructions are given by the software that tell which vertices are connected together as 'edges'. An edge is simply a line connecting two vertices together, and while it also has no volume, it does have length. To complete the cube, still more instruction are necessary to define what groupings of edges produce a 'polygon'. Like in geometry, a polygon in computer graphics is a plane defined by its edges and vertices that produces a surface. By virtue of how they are defined and arranged, the 6 polygons together, one for each side of the cube, produce the three dimensional cube shape.

In panel one, MODO represents vertices as tiny white dots. Panel two illustrates the connecting edges between the vertex corners, with panel three illustrating the six polygon planes that make up the final cube shape. This object is considered a '3D model' as it is fully three-dimensional (taken from the XYZ dimensions that define it), just like a real box. Additionally, this 3D cube has mathematically perfect perspective, and it can be moved, rotated or scaled without losing any of its original properties. And don't worry, making a cube in MODO is way easier than describing how one is built in 3D. It actually might be hard to believe, but if someone wanted to model something as complex as a car, it is defined in exactly the same manner as this cube, it's just several orders of magnitude more complex, and while the model itself is more complex, it's not really a lot more complex to make, once you understand the tools and what they do.

One aspect of creating these models that can be troublesome for users is the fact that, while dimensionally accurate, they are still displayed on a 2D screen, the world that exists inside the software is fully three dimensional, with all the depth that our real world has (I like to think of the monitor as a window into the applications virtual world), but the viewing medium can make it awkward to navigate. MODO is designed to make this as painless and simple as possible, but there is a degree of familiarity one needs to acquire to feel comfortable working in this manner.

Going from a 3D model to a 3D image

Once created, these virtual collections of surfaces (be it a 'cube' or a 'car') are further processed by the software, using very complex mathematical algorithms that work in a similar fashion to how light acts in the real world and this is all captured by a virtual camera in a process known as "rendering". The ultimate result of the rendering process is what is called a 'bitmap' image. A bitmap is simply a collection of tiny individually colored squares, just like the 'pixels' on your monitor; when viewed together as a group produce a recognizable image. The greatest benefit about generating images virtually is users can control every single aspect of the image creation process. Photographers are at the mercy of reality, but in 3D, images can be as stylized and artistic, or as photographically realistic as you want, it all depends on your determination and dedication.

Finally, I feel I should mention that even though the term mathematical has been tossed about quite a bit, the math-phobic shouldn't get too worried, working in "3D" is often times more art than science. The more you learn about 3D computer graphics, the more you'll have the power to generate and manipulate the polygons and pixels, producing results that are limited only by your imagination.

TIP: Are some of the terms above still a little confusing? You can easily find definitions for virtually any word using an online search engines such as 'Google' or 'Bing' . If you append the term " `define:` " to the front of your word (no space), you will receive a dictionary-like definition instead of links to pages with that word on it.

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