Last modified on 24 October 2010, at 19:26

Blender 3D: Noob to Pro/Understanding Coordinates

This tutorial has been created with Blender v2.47

Figure 1: Right-handed coordinate system in Blender

You may already be familiar with the X and Y axes from math class, where you were asked to plot points on a set of axes, namely the X and Y axes. 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 point 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.


Figure 2: Right handed system

Because of the way the axes are orientated, 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.


Figure 3: Direction of rotations

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.