Representing 3 dimensional objects with 2 dimensional media

Let's start with 2 dimensional objects on a screen or sheet of paper.

The first two dimensions can be visualized as two number lines perpendicular to each other and flat on the plane established by the screen or paper.

The horizontal red line is the X axis and the vertical green line is the Y axis. Where they cross is the ordered pair (X, Y) (0,0) X and Y both equal 0. This point is known as the origin.

The picture on the right shows the Z axis in blue. The Z axis passes through the origin and is perpendicular to both the X and the Y axis.

The next set of three pictures show the center of a cube centered on the origin and a lavender sphere centered on (3, -3, 3)  X=3, Y=-3, and Z=3.

This is bigger than I really wanted but I want you to be able to see the coordinate system down in the lower right corner of each of the three pictures. The arrows are pointing in the positive direction of each of the axis. This is showing the orientation but has no connection to the numbers of the ordered pairs or triplets.

The left graphic shows the X Y plane from the top view.

The top right graphic shows the front view and the Z, Y axis (plane).

The bottom right shows the axometric view.

Quite often seeing two or more perspectives of the same object can help in understanding what you are looking at.

One more detail about the coordinate system and the relationship of each axis to the other two.

The right hand rule

Look at your right hand with the thumb, index finger, and the middle finger each extended at right 

angles to the other two.

 The thumb is pointed in the positive X direction.

The index finger is pointed in the positive Y direction.

The middle finger is pointed in the positive Z direction.

Some orientations you can match with your hand. Others are going to need to be mental gymnastics.

Ok to start with, I'm not sure this is the best platform to teach FREECAD with. Blog order means that the first most basic post are at the bottom of the page. Probably off the page and several pages back in history.

The second problem is making money off of this. Google Adsense sounds as though it would bring in less than ten dollars (pennies) a month for the size of audience I would expect for this subject. I am planning to write a book about FREECAD and this could be a blurb - sample for the book.

Third problem is that it looks as though the templates all use the middle half of the screen for the main posts.  Screen shots for FREECAD will need more of the screen than that. There should be a workaround for that.

Well the width problem was simple enough. Just go to template designer and adjust the width.