Hi DtS,

Very briefly ( there is a guide out there somewhere that goes into detail....)

The shield in the BIF plate has a set of co-ordinates that define where it is (top left corner, bottom right corner) - these are defined in the textures/men/BIFname/shields.txt files accompanying each BIF.

When it is rendered, another set of co-ordinates defines where it is drawn relative to the unit 'origin' - this is a set of four co-ordinates, one for each 'corner', as this allows 3D perspective to be simulated. It's not true 'scaling' as you are thinking. It's more a case of 'draw this area into that area'. These co-ordinates are in the textures/men/items/shield#/unit-name/action.txt files. Each action for each unit has (IIRC) 48 sets of 9 coordinates - 4 (x,y) co-ordinates to position the corners, and a single 0/1 to define whether the man is drawn before the shield or vice versa (for when the shield is on the opposite side of the body to your viewpoint). 48 sets because there are four viewing angles in 12 frames of the BIF.

The reason some shields (usually in mods...) are drawn larger in the BIF is purely for resolution - notice most of the original MTW shields are pretty basic in design.