Image center (principal point) potentially not set correctly when loading a new project
Steps to reproduce:
1. Open markerCasern test example
2. Open multiColorMarkerWithAruco_dictMip36h12 test example
Problem: center is not read correctly

Excerpt from pet-file:
```
<INTRINSIC_PARAMETERS [..] CX="2380.0599999999999" CY="1911.8699999999999" [...]/>
```
Could reproduce on commit `7637410538207f2cb6df0e33a3e4fb033ca3c280`, i.e. before the extraction of the `IntrinsicBox`
issue