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Varkon Interactive users manual

# Curve accuracy

Curve accuracy is the same as display tolerance or graphical approximation error in other systems. It has nothing to do with the real accuracy of a curve, only it's graphical appearence. Curves and surfaces in Varkon are probably more accurate than in most systems including systems that claim that they have class A surfaces.

Systems that display curves do that by approximating the curve with short lines or vectors (vectorization). The number of vectors must be kept within reasonable limits or the process will take too much time. With too few vectors however, the visual effect is disappointing.

The pictures above show the same curve with curve accuracy set to 0.1, 0.5 and 1. As you see, there is a dramatic change in quality between 0.1 and 1 but higher values would not differ much. This is due to the fact that Varkon automatically adjusts the length of the vectors to the curvature of the curve and that the display itself has a limited resolution.

Default value for curve accuracy is 1. The smallest value you can use is 0.1 and the biggest is 100. The default value usually works fine but if you need to display curves with more vectors it is usually enough to increase the value to 2 or 3. Varkon automatically increases the curve accuracy 3 times when plotfiles (*.PLT) are created. This means that a printout on paper is usually smoother than the same image on the display.

Curve accuracy controls the display of arcs and curves. It also controls the curves used to display a surface in wireframe mode. When surfaces are shaded with light and color Varkon uses the curve accuracy factor to control the number of triangles used for the shading process.

The pictures above show the same surface shaded with a curve accuracy of 1 and 3 respectively. Be carful to increase this value too much if you don't have a very powerful graphics display card.

Varkon version 1.19C svn# 97