lets take snow as an example
Activate creature bulider id is ( 2 ) so in npcgen.data we get its trigger link
and we get ( 7 ) so look for the trigger link to find the id of the dynamic object (snow)
we get id ( 10 ) so now we look in dynamicobjects.data in configs.pck
and we find id ( 10 ) = 场景\圣诞雪.gfx so open that file from gfx.pck with notepad and find what image its using
oh look its called snow.bmp
open snow.bmp in photoshop, gimp whatever
and do what you like with it
you can clone stuff like that and give new ids ect and away you go