RVMAT – ArmA: Armed Assault Talk

Additional Info

 Specular map is a complex bitmap. Each color chanel has its own purpose. You should understand well the way of calculating pixel colors in scene before you paint those textures. 

As written in http://community.bistudio.com/wiki/ArmA:_RVMAT value of each pixel is calculated with RVMAT values and engine lighting values.

Texture _SM has diffuse values in RED, specular in GREEN and, Specular power in BLUE chanel. _SMDI does not use RED chanel (better compression) GPU calculates those values automaticaly as Diffuse = 1 - Specular. 
When you use specular map - diffuse, specular in RVMAT should be 1. Then paint B/W map with maximum specular and minimum specular values you imagine on surface. Than choose minimum (black) and maximum specular (white) values and change the bitmap levels to those values. (c)Armored_Sheep

--Bdfy