@marchik Thank you so much!
About Bokeh, I think it's because I didn't calculate the depth blur in 3d. It was much too heavy in terms of calculation time, and complicated to animate if I wanted to come back to it.
So I opted for frischluft in after effects. In addition, I was able to calculate shots separately and with different noise limits. For a background, I could therefore leave some grain to save calculation time, then in composition I blur with frischluft.
About raindrops and splashes, you are totally right! This is really the part where I struggled the most.
It's not perfect and I'll try to improve on that. These shots were made 2 years ago, I think I could do better today.
But because I calculate everything on one computer, I didn't want to recalculate there shots.
The real goal of this project was to make a 2-minute video to improve my production skills, organization, artistic direction and sound design.
Thank you everyone :)