Questions about Metashape's 4D processing tool

[glennk]

Hello,

I am scanning human eyes on several poses.

I used the 4D processing tool (GUI) to align my scans and I does not work very well.
https://agisoft.freshdesk.com/support/solutions/articles/31000155179-4d-processing
I tried a simple ICP algorithm with outliers management and the alignment behaves better (see attachments).

I have several questions (they might be correlated) :

• How does 4D processing align the frames ?
• Does 4D processing affect the final textures ? (by taking information in each frame somehow)
• How to perform 4D processing from python ?
• What are the differences between 4D processing and processing all the chunks followed with a chunk alignment ?

Thanks,

Glenn