3D Mapping new structure that is not yet on ground map

How do I create a 3D mission around a new structure/building that does not yet appear on ground maps? Is it possible to walk around the structure and plot specific GPS waypoints before the mission using the DroneDeploy app? I understand I can plot waypoints with the DJI app, but that would make it necessary to operate the camera manually and capture images by simply estimating overlap. I’m looking for a bit more precision. Thanks in advance…

I’ve been surveying solar farm panels using a georeferenced CAD drawing of the site and then plotting waypoints around that.

Do you have access to a drawing of the site or even an already uploaded full tileset from something like MapTiler?

I do this daily. Find some reference point or create the map in the field. Yesterday I used my own location as the corner of a map. from there i knew visual direction and rough size. I flew more area than i needed just so i would have the target area captured. it would be nice if the flight plan offered size dimensions when you plot it.