1. A method for accurately displaying superimposed images, comprising: a) storing a base image having a first feature and a second feature in a storage device of a computer; b) receiving data indicative of a full-scale dimension between the first feature and the second feature; c) scaling the base image to have a predefined dimension between the first feature and the second feature when displayed; d) scaling an accessory image based upon at least a ratio between the predefined dimension and the full-scale dimension; and e) superimposing the scaled accessory image onto the scaled base image.