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Table 3 Comparison of arc length and the orthographic projection

From: Quantifying the variability between multiple multiplanar reconstructions of computed tomography scans

Angle (°) Arc length Orthographic distance Underestimate (%)
0 0.000 0.000 0.00
1 0.017 0.017 − 0.01
2 0.035 0.035 −0.02
3 0.052 0.052 −0.05
4 0.070 0.070 −0.08
5 0.087 0.087 −0.13
6 0.105 0.105 −0.18
7 0.122 0.122 −0.25
8 0.140 0.139 −0.32
9 0.157 0.156 −0.41
10 0.175 0.174 −0.51
15 0.262 0.259 −1.14
20 0.349 0.342 −2.02
  1. The vectors found in the study define points on the surface of a unit sphere which must be projected onto a plane for graphical analysis. The amount of error introduced by the orthographic projection relative to the true distance between the polar contact point between the sphere and the plane and another point on its surface is shown for angular deviations from the axis normal to the plane. Typical angular deviations reported in the literature for the femur in humans are 1°-11° [2, 9]