A non-transitory computer-readable medium stores a program. The program causes the computer to: acquire photographed image data which is generated by photographing, in an imaging apparatus, a photographed object indicating multiple reference points; acquire pieces of position information which indicate positions of the multiple reference points in the photographed image; map pieces of relative information to the respective reference points by analyzing relative positional relations between the multiple reference points in accordance with a first method; map the pieces of relative information to the respective reference points by analyzing relative positional relations between the multiple reference points in accordance with a second method; and determine a certain reference point as a reference point to be excluded, in a case that a first mapping relation is different from a second mapping relation.