Talk:Map projection Plug-in

Suppose we have a source map whose projection is unknown but which shows latitude&longitude lines or some other rectilinear gridding. Shouldn't it be possible to create a reprojection tool that runs based on user input from a point-and-click interface? Say, have the user designate (with clicks) any six points on the source map and at the same time specify their coordinates (in the source map's grid system). Assuming the user chooses wisely, this should be sufficient information to determine the type of projection, shouldn't it? Do you know of any "smart" reprojection routines like this that have been developed?