The “rayepsilon” pin in the kernel nodes is used to ensure that geometry does not cast shadows on itself, so provides a gap between surfaces when calculating shadows. For close-up rendering, it should be set low, so that these gaps are not visible. For “distance” renders, where the camera is a long way from the rendered geometry, the “rayepsilon” will need to be increased, since the geometry being rendered will be a long way from the camera and the vertices will appear to the Octane renderer to be at the same points in space (and thus cause shadow artifacts with a low “rayepsilon”).
In summary:
Note: A “rayepsilon” of 0.075 = 7.5cms.