Blender 3D: Noob to Pro/Thinking in 3D

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Modeling in 3D is a lot like a high school geometry class. In 3D, there are no relative viewpoints such as up, down, left, right, front or back. You will have to reorient your view into a more stationary, concrete outlook with XYZ, also known as Cartesian, coordinates. Of course, since not all of us had the privilege to, e.g. take a high school technical drawing class, the fundamentals of 3D modeling may be elusive to grasp. But fret not, for by the time you finish this chapter, you will be able to visualize the world in a new way, which you will be able to apply to Blender, as well as any CAD/3D modeling application.

Also, as with any other subject, 3D modeling has its own special vocabulary. All new terms will be highlighted bold and shortly defined.

[edit] 3D Coordinates

You are probably already familiar with the X and Y axes from math class, where you were asked to plot points on a graph. Since we will be dealing with three dimensions, you will now become acquainted with the Z axis.

It feels quite natural to let the Z-axis run up and down, and keep the X-axis pointing to the right, but where shall the Y-axis go? Well, it points away from you into your monitor (Fig. 1). So how do you go about graphing it? Well, to sketch it on paper, you would draw a line that appears to go backward and draw tick marks to show its depth.

Because of the way the axes are oriented, this system is called right-handed. If you let the thumb of your right hand point in the direction of the X-axis, your index finger points in the direction of the Y-axis, and the braced middle finger points in the direction of the Z-axis.

As you can see in Fig. 2, you can rotate the coordinate system, so it is not important where the axes point to, as long as their relative relations are kept, e.g. you will often find that the Y-axis points upwards and the Z-axis points towards you.

If you use your right hand again you can also determine the direction of a rotation. If you point your thumb into the direction of the positive rotation axis and close your fingers, they show the direction of the rotation, i.e. the angles get larger in that direction.

There are several ways to depict a 3D object on a 2D surface (paper, monitor, etc.). In this book we will cover the three most important types of projections/views: orthographic, isometric and perspective.