A three-dimensional measuring apparatus or similar contour measuring apparatus of the present invention includes a projector for emitting light, a lattice film or similar light transmitting member, and a camera. Light issuing from the projector is transmitted through the lattice film to illuminate an object to be measured. The lattice film is movable to a plurality of projecting positions in a preselected direction. The camera shoots the object being illuminated by the light. A driving device for driving the lattice film includes a cam follower associated with the lattice film, and a cam for guiding the cam follower. The cam has a cam surface including a plurality of contiguous, insensitive portions each for causing the lattice film to remain in a halt at a particular position when the cam follower contacts the insensitive portion.