An illumination marker includes a light source and an optical attenuation cover coupled to the light source. The optical attenuation cover is configured to attenuate an intensity of light that passes through the optical attenuation cover based on a length of an optical path of the light through the optical attenuation cover. In some embodiments, the optical attenuation cover may be embodied as a physical barrier cover and include light-blocking structures. Additionally, in some embodiments, the illumination maker may include a diffusive or retro-reflective core rather than the light source.