Oh.  I didn't realize it was an unpopular film and I thought the people here were into Kurosawa.  OK then!  
You might not know about it because it's a Soviet film.  Yes, it's based on the book.  
 
Basically it's an explorer re-telling events that occurred on an expedition.  His crew meets a hunter in the woods who has spent his entire life in the forest.  As a result, he's a total badass and helps the guys survey the area.  
It's really about the hunter and the explorer, their relationships and what they learn from each other.  
It's all (except for a few segments) filmed in the Siberian wilderness, throughout various seasons and landscapes.  
SPOILERS FOR THE FIRST THREE MINUTES OF THE FILM! 
    Spoilers! | 
Since it's a re-telling of events, in the very beginning you discover that Dersu is dead.  After a while you start to wonder with each new scene, "is this where he dies?"  His eventual death still manages to catch you off guard. | 
   
 
It seems to me than Kurosawa would be interested in the project because it has a pretty obvious message of respecting nature and a more "primitive" way of living.