There are also range issues. The larger the physical pattern the further away the pattern can be detected and so the great volume the user can be tracked in. Table 1 shows some typical maximum ranges for square markers of different sizes. These results were gathered by making maker patterns of a range of different sizes (length on a side), placing them perpendicular to the camera and moving the camera back until the virtual objects on the squares disappeared.
Pattern Size (inches)
Usable Range (inches)
2.75
16
3.50
25
4.25
34
7.37
50
Table 1: Tracking range for different sized patterns.
This range is also affected somewhat by pattern complexity. The simpler the pattern the better. Patterns with large black and white regions (i.e. low frequency patterns) are the most effective. Replacing the 4.25 inch square pattern used above, with a pattern of the same size but much more complexity, reduced the tracking range from 34 to 15 inches.
