Open the object with which you would like to make a normal map of in ZBrush 3.
Choose “Displacement” from the menu list on the right side of the ZBrush window. Create a Displacement Map of your object by selecting “Adaptive” and your personal preferences.
Click on the “Alpha” square on the bar on the left side of the screen. Select “Crop and Fill” from the pop-up box.
Click on the “Material” option on the left bar of the screen and change your material to “ZBrush 2.”
Select “NormalRGBMat” from the bottom of the “Material” box.
Click on the “Alpha” square on the bar on the left side of the screen. Select “Crop and Fill” from the pop-up box once again.
Click the “Stroke” option on the bar on the left side of the screen and select “GrabDoc” from the pop-up box.