Hi everyone !

Firstly for AdrienB :Your workflow looks OK but very approximate. I would advised you to search deeper in the forum to precise it

Then for Blackbyrde:As you may have seen on Matt's link, I've worked a bit on wall orthophotos. Indeed, known-points (GCPs) or known-scales would be mandatory if you need a scaled orthophoto but, if you don't have any of them, you shouldn't need it ! Nevertheless, GCPs would give you the possibility to accurately correct your 3D modelling. Without them your model would be a bit indecisive.

As you know, you can define artificial points on your Egyptian wall. Then, you easily understood 3 points are needed to define the plane that while define your ortho-rectification. Fortunately, you don't need them to form a right angle ! Indeed, when you go to "Build Orthomosaic" panel, you can define:

- The type as

**Planar**- The projection plane based on

**Markers**- The two axis using your markers, for example

**horizontal from A to B** and

**vertical from A to C**.

- But you can also

**tick one of the two axis that will define your orientation plane**. Your third point would only be used to orientate the plane around the axis, the angle will stay right !

In other words, you would only need two points at the same altitude (horizontal axis) and a third one, randomly place above your two first. Just be careful this third one is not too "behind" or "in front of" your wall to be sure your plane will be vertical !

I hope I was enough clear

Regards