### 3D Transformations – Standard

ChaosPro knows two methods for 3D transformations: Standard (the old way) and OpenGL (since V3.1). You switch between these two modes by using the radio buttons at the top of the window. The image above currently has selected the standard mode.

In this mode the image gets created by using orthogonal projection. This projection mode has some drawbacks, but also some advantages (yes! That’s why I chose to use it!). The most important advantage is that it’s fast: Orthogonal projection works by simply ignoring the distance, not applying any perspectivity. So the transformation routine can be very fast. Due to that it’s possible to write a very fast algorithm for “hidden line removal”.

But as you can imagine, without any perspective images won’t look realistic, so some special parameters need to be introduced in order to give the image a more realistic look. But the most important drawback of using orthogonal projection was that it was not possible to (horizontally) rotate the image: When I tried to implement that feature, a moire effect appeared, thus making the image useless.

Have a look at the image below to see an example: Do you see that there’s no perspective? A mountain far away has the same height as a mountain at the front. Fortunately the human eye can be fooled!

So orthogonal projection allows you only to change the vertical angle from -90 degree to 90 degree.

The settings for this transformation mode have been divided into three parts (see image at the top of this page):

• Angles : The settings on this tab let you change the angles, i.e. the view angle and the light angle. In addition to the light angle you can specify some settings for the light.
• Transformations: This tab contains all settings which are responsible for calculating the height of the object, i.e. on this tab you can adjust a spline which maps from color value to height. Another set of parameters try to introduce some kind of (artificial) perspective by multiplying the height with some factor which gets smaller for rows lying far away.
• Colors: And finally, on this tab you can find all settings responsible for the final colors of the object and background.