Hi Romain, this week I've been working on coregistering a dem with ICESat-2 with your code modified by Désirée. She added some plotting for understanding the iterations in the NuthKaab algorithm. With precious help from Erik (who joined us this week) I made the code OO. Hope this makes sense to you, ofc we can improve this more and test it better than I did. We could also set up a meeting if you want.

This function [_plot_iterations()] plots the graph of Normalized elevation difference vs Aspect and the fitted curve for each iteration of the NuthKaab algorithm. To be able to do this, in the _meta attribute I added the following [I am not entirely convinced it's the proper place/naming]:

• partial_offset_east_px (list)
• partial_offset_north_px (list)
• partial_offset_vertical (list)
• aspect -> array with the aspect for all the points
• differences -> list of arrays with the el. differences for all the points
• slopes -> list of arrays with the slopes #TODO: fix the slope computation, now it computes the slope with horizontal distance in pixels.

• these last two could be together (as normalized el. difference)
• all the lists are as long as the n of iterations.

TODO & questions:

• it would maybe be clever to reduce the numerosity of the lists in the _meta. for large dems it could be too much information to handle
• modify the slope function (right now the angle represents m/pixels)