Photogrammetry Software Critiques ?

I was hoping to save myself some time manually scaling from photographs, so out of curiosity I did a “Google” search on the term “photogrammetry software” and found several hits, including one for PhotoModeler products:
http://www.photomodeler.com/index.html
Have any of the CADAM users out there used this or a similar product and, if so, what was your experience ? It’s pricey, but I’d still appreciate your comments or to learn whether there are cheaper downloads that can do something adequate for model railroading.
Bob
NMRA Life 0543