masking and scaling studio projects

Question

I am looking to do studio photogrammetry on some museum pieces. I want to use scale bars in the photographs to scale the models. However, I also want to use Lightroom to mask off the objects to remove the turntable and background. Obviously that will remove my scale bars. 
 I was thinking that it might be possible to bring in 2 photo groups. One with the unmasked photos, including the scale bars. The other with the background masked off. Then run an AT with all of the photos, set a scale constraint, run another AT, then take out the photos with the background and run another AT and reconstruction. I don't have any idea if that will allow my scale to carry through to the reconstruction without any background information. Does anyone have any experience with this situation?

Scott Ernst · Answer

Well, I ended up doing some experiments and figuring out the solution. It went more or less how I thought I would try it. At first I tried putting the scale bar on the table next to the turntable, but of course that didn't work at all since the object was moving while the scale bar was stationary. The AT failed completely. Next I put the scale bar on the object and took 6 photos as I turned it. Then I took off the scale bar and took all of my photos. I ran all of these through Lightroom, masked off the background and reduced the exposure to make the background black. 
 I did my first AT with the 6 photos that had the scale bar and created a scale constraint. After that AT was done I did another AT from that one, but this time I added all of the rest of the images. You can see that CC started to remove the scale bar since it now seemed like a moving object, but that was OK. They went together fine. Then I took out the 6 scaled photos and ran another AT. When I removed the photos I got a warning that they were connected to a constraint but I ignored it. I ran another AT from the last one, checked to see that the scale was still correct and then ran a production. 
 I had done white balance on the images and the reconstruction looks color correct in CC. For some reason in CC Viewer it looks very orange. If anyone has any thoughts on why that is happening I'd love to hear about it.