### Color and Perspective

This tabsheet determines the way the surface is colored. There are several possibilities:

• Only one color (the one that was selected in the information window;
• Coloring according to red (x-coordinate), green (y-coordinate) and blue (z-coordinate);
• Coloring according to height (both in color or monochrome);
• Coloring according to a color function that can be entered (and activated) in the information window.
Moreover, it is possible to make the surface completely reflective such that it reflects some (artificial) environment map. Note, however, that this option must be combined with one of the previous mentioned coloring schemes, and that the effect is only visible if the graphics adapter of your PC supports it. On recent computers, this is certainly the case, but some older models might not have these capabilities.

We remark that coloring can be disabled by unchecking all coloring buttons. Lines that are activated (see tabsheet Lines) are even then still visible, making it possible to obtain wireframe type models.

Also, the choice can be made between central and parallel projection. Central projection corresponds most to the way we observe objects. This is because the human eye functions like a "camera obscura" and such a camera uses central projection. A typical property of central projection is that parallel straight space lines tend to go through one point, the so called vanishing point. Parallel projection on the other hand corresponds better to perspective drawings we make ourselves. Because of the simplicity we usually draw parallel straight space lines also parallel in projection. Our brain doesn't have much trouble in interpreting correctly this from our normal observation deviated model. The advantage is that parallel line pieces that have the same length also after projection remain of the same length. This means that graphics based on parallel projection are more appropriate to compare distances.

Finally, the background color (default is white) can be set to any color and the object can be made transparant. The transparancy degree can be changed with the slider. We remark that the transparancy is actually a type of pseudo transparancy. This means that sometimes, not all parts of an object are equally transparant. Also, it sometimes depends on the viewpoint and on additional settings.