An inexpensive optical module that avoids misalignment of optical axes and is fixed together with high reliability. The method of rendering 3D graphic data may include grouping objects from among transparent objects included in graphic data, which overlap each other in a 3D space, and rendering the group and remaining objects excluding the grouped objects, in an order determined according to the distance between the group and a viewpoint and the distance between the remaining objects and the viewpoint. The software module may include logic to cause the client device to broadcast a signal comprising location andor identification information associated with the client device. 9% of the total composite weight. , preferably by less than 15\xb0 C.