Figure 8

The problem of counting the unique rays for a given number of views is illustrated here on an N × N = 4 × 4 picture with R = 4 views with rational tangents. We were able to place only 3 stars so that none of their rays overlapped. Their centers are shown as red circles and their unique rays as dashed lines. The missing rays are drawn as solid green lines. For the 16 pixels shown here, the total number of unique rays is therefore T = 3R + 8 = 20. This is substantially less than T = RN ² = 4 × 16 = 64. Thus 31.25% of the possible rays with this star are unique.