Accuracy of Measurement in 3D


has someone experience with measurements in 3D - what are the limited factors ?

Following example:
Digital Terrain model or digital surface model with accuracy in position of 1m and height of 1.5 m for example. On this terrain data a orthophoto with resolution of 0.2 m is drapped.

Does the orthophoto influence the accuracy of a measurement in 3D or not ?

I think you could position a marker with the orthophoto in a better way, but the underlying accuracy will not change !

What is your opinion ?