Schematics of the used geometry. The impact point ρ (solid blue line) gets transferred to the camera plane along the green dashed line, if the muon is inclined (see the definition of ψ in Figure 1). The resulting impact distance with respect to the camera (dashed purple line) is denoted as ρ′. A possible hole in the center of the mirror support structure is drawn as a circle of radius r. The half-side length of the camera is denoted by A.