hi,

i have live video with animation, and in one scene, i have a character coming out of water. does anyone know how i can create an object that will mask parts of the characters body when they are obscured from view, or to show parts of the body as slightly opaque (under water) ?

thanks, been racking my brains and am not too sure how to do this…

Hi there,

To mask the lower half of the character, make an object, let's call it “water_mask”, containing a Grid SOP that matches the water level then under the Render tab of the water_mask object, turn on the Matte toggle & set the value to 1.

To create the transparency mask, render the character only then in COPs, or your favourite compositing software, subtract this full character render from the masked character render. You will now have the bottom half as a mask for the under water effect.

I hope the above helps!

Cheers!
steven

thanks for that, that definately helps!

although i'm sill a little confused about a couple of things (tut, newbs… *grin* ). will i have to turn off the render tab on the water_mask SOP?

for the under water opaque effect, i do a render of the full character in COPs, then subtract it from the full masked character render ? if that is correct i'm a little unsure how to subtract…

Hi there,

Nope, leave the render flag on the Grid SOP when you're using it to mask out the character. However, when you're rendering the full character, just turn off the water_mask object's display flag.

To perform a subtract, put down a Composite COP & select “Subtract” from the Operation menu. Next, connect the masked character to Input 1, the full character to Input 2 & you should have the bottom half of the character.

Please let me know if you would like me to provide an example.

Cheers!
steven

that's fine steveen, thanks. i sorted it out from the information you gave me