Pardon me, but I have the impression you both think too complicated...
I think you have the house-model and a picture. So measure the place where the photo should be apliccated. Open the photo in a program (Gimp, Showfoto, Photoshop or something similar), settings for measurement in your prefered system (metric or imperial - not dots or something like that) and than resize the photo with your measured results. Maybe you must crop your photo for saving the ratio between high and width. Otherwise you could get distortions.
Have fun und best wishes from the other side of pond
Arnim
Arnim v. Herff