For Maya software renderer only.
To increase or decrease the mask value for an object
During rendering, Maya first generates the mask channel, then multiplies the mask values for the object by the Matte Opacity value. For example, if Matte Opacity is 1, the mask values for the object remains unchanged; if Matte Opacity is 0.5, the mask values for the object are half their original values.
To set the mask value for an object to a constant value
If the object is transparent, any objects behind it appear in the mask channel.
During rendering, Maya first generates the mask channel, then sets the mask values for the object to the Matte Opacity value. For example, if Matte Opacity is 1, the mask values for the object are 1; if Matte Opacity is 0.5, the mask values for the object are 0.5.
To set the mask value for an object to zero
During rendering, Maya first generates the mask channel, then sets the mask values for the object to 0. If the object is transparent, any objects behind it will not appear in the mask channel.