We want to take the opportunity to ensure that you are aware of the differences between merging and aligning projects.
- When projects are merged the combination of information from different projects will be used to create a new one single project. That means that after running step 2 and 3 you will have results based on the new single project created after merging.
- When projects are aligned they are treated as individual projects but they will have the same referenced location (they will overlay) which will allow you to proceed comparisons.
That being said what you will want in this case is aligning projects. Please note that is important to choose the location of your reference point on features that will not change in time (seawall, concrete features, piles etc…)
As for the comparison depending on the specific purpose it is recommended to used third software party.
For more information regarding the third softwares that support Pix4D Mapper outputs please see the article :https://support.pix4d.com/hc/en-us/articles/hc/en-us/sections/200591089