Modeling tenement house only using photographs from random angles and mostly useless blueprints, what could go wrong... but I have to fix it I've got a job and I've got dozens of pictures of an old apartment house and blueprint that let me get mostly basic info like length of some walls so I can model a refurbished object that someone will put over the image and possibly a video clip that presents the actual object. So after I drew some lines with a blueprint, I set the camera at a particular angle, set the picture as a background, position and FOV around 41 degrees by hand, and then I modeled what blueprint couldn't give.



Before I finished the corner I wanted to set another angle and then I ran into big big troubles. I sat for 2h and the closest I got with a camera (which fov is different and is around 72 degrees) is this. Don't look at the roof as it was just temporary, I care about the elevations.





I supposed it to be exact, but it's not and now I question if I'm able to continue the work if I can't get a reference. Do you think it's as bad as I think it is? Should I worry about it? What would you do?
This is a nightmare to set up and many blender modellers would use a program called fSpy.

The program is free and allows you to set up your camera to photos perfectly. You'll need to also download the blender fspy addon. 

In fSpy, once you've set up your lines in the program, save your fSpy file then go to your blender file and import the fSpy file. File > Import > fspy and browse to find your file.

That will set up your camera perfectly. I do recommend watching the tutorial for using fSpy however.

Document tutorial:
https://fspy.io/tutorial/

Video tutorial:
https://lesterbanks.com/2018/11/perfect-camera-match-fspy/

Download fSpy:
https://github.com/stuffmatic/fSpy-Blender/releases

blender addon link:
https://github.com/stuffmatic/fSpy-Blender