Once the tube has been well marked/traced, it can be marked and then referenced on other photos.
Bent Tube marks on photos are referenced in the same way as points, edges, curves and cylinders etc. See Referencing Tools. Bent Tubes can be referenced using Referencing Mode (see Referencing Marks) and Quick Reference. Like other referenced objects you can reference between photo marks, and between 3D representations (3d view and photo projections) and marks.
Once a Bent Tube has been marked and refererenced on two or more oriented photos, its 3D shape will be computed. You can see the results in the 3D Viewer or on photo projections by turning on the appropriate visibility settings. Note that viewing the 3D Bent Tube in photo projections is a good way to study how well the Bent Tube has solved (esp. good to look at the projections on photos where the tube was not marked). See the Troubleshooting section for more information on what to do if the Bent Tube does not form in 3D as expected.