When using the manual Maps Made Easy georeferencing, such as the Basemap or Manual GCP entry workflows, there are a few common and very small mistakes that can cause some big errors. This process requires a lot of care and attention to detail to make sure that the outputs will be as expected.
As with all Maps Made Easy processing jobs, the images get processed into a 3D model. For the manual workflows, this happens without any influence from the GCPs. The GCPs really only come into play when it is time to align the created model with the real world. The GCPs which are just pairings of pixel locations and real world coordinates.
Anchor Points are pairs of GCPs that say these two pixel locations in these two images represent the same point in the real world. For example, this corner of this rock in picture A is the same as this corner of this rock in picture B. Maps Made Easy uses this information from at least 3 Anchor Points to apply a scale and rotation to the already created 3D model.
If the point pairs are not of the EXACT same real world locations in the images, the small distance between those points tells our processing system that the distance between them is 0. Then when Maps Made Easy does the math to scale and rotate the model into place, there is a 0 in there when calculating some averages and that average gets thrown way off.
This is not something that we can fix after the fact and the job will need to be fully reprocessed to come out properly. The good news is that the 3D model output is probably just fine.
Think of setting Anchor Point locations like installing legs on a table. If they are too close to each other, the table could tip over. If the legs are all in a line, it is definitely going to fall over. If one is installed right at the edge of the table, it might break off and leave you with only two.
The guides for these workflow are posted here: