Exploring 3D space with a computer – an Introduction
Adrian Oldknow
Dotty things
The dotty things are just points, like A and B above, which can be in the ground plane or anywhere in space. Of course they should have no length, width or height - and so are technically zero-dimensional. But they will usually be treated as spheres and be shown in colour, and maybe with labels. Here are some dots to play with. You will see that they are in a variety of colours, sizes and shapes. Also that the labels are in different colours, sizes, styles and fonts. Can you drag the labels to different positions? Can you drag the points to different positions? Can you spin the picture to determine which points are always in the base plane?
If you download the Cabri 3D file 
Points.cg3 then you will be able to create more points of your own, as well as modify the points and labels shown. Use the `Manipulation' tool (the arrowhead icon at the left of the Cabri 3D Toolbar) to select a point or a label and right-click to open the menu to change the appearance.
* Note that I have changed the appearance of the base-plane to make it more transparent, and also masked the three unit vectors. The other choice of dotty thing: `Intersection Point(s)' can't be used until we have some other types of object.
