How to config nginx with attached diagram

How to create correct config using attached diagram?

This config cant get file from folder imagetest2 for files stored 'as is', only with rewrite rule.

server {
listen *:80;
server_name imagestest.local;
root /var/www/imagestest;

set $other_dir "/var/www/imagestest2";

location ~ / {
try_files $uri $other_dir @rewrite;
}

#try for splitted
location @rewrite {
rewrite "^/(.*)\/([0-9]{1,3})\/(.*)" "/$1/0/0/0/$2/$3" break; #1-3
root $other_dir;
error_page 404 = @fetch_image;
}

location @fetch_image {
rewrite ^(.*)$ http://somehost$request_uri permanent;
}
}

Link to diagram http://tinypic.com/r/28wgif5/8 (forum.nginx.org files seems to be not working)