Sunday, January 25, 2009

CG multiples/smears

So the Summer 2008 Student Showcase from Animation Mentor had a piece by Henry Sanchez that raised some discussion. Basically Henry was making multiples, like in the old 2D days, when a single frame might have 3 right hands to show the speed of it passing, similar to smears. There was conjecture but never a solid answer on how to do it. Nathan Fulton posted up a walk through of how to do it on the 11second club, which I'm copy pasting here so I don't lose it. Again, Nathan Fulton figured this out/wrote it down, I'm just copying it. Thanks Nathan :)

Here's how it works: Luckily for us, Maya can have fractional frames instead of just integers!
First I made this simple animation using just a few keyframes the normal way. A big chunk of movement happens between frames 5, 6, and 7.

Frame 6 has lots of speed on either side of it, so I decided its "ghost frames" are going to be on 5.75 and 6.25.
Frame 7 is a slow-out, so its ghost frames are on 6.5 and 6.75

Next what I did was type in these fractional frame numbers into the text box right next to the time slider. Once I had my fractional frame set, I could make further tweaks to the pose.

Then I selected the mesh of the character's body, and selected the menu Edit -> Duplicate Special -> Options box.

In "Duplicate Special Options" I set it to "Copy" and un-checked "Duplicate input graph" "Duplicate input connections" and "Instance leaf nodes."

This created a new ghost mesh of the character on that fractional frame.

I then selected that ghost mesh, set the time slider to the frame before it, set its "Visibility" to "off" and keyed it. Stepped forward one frame, keyed visibility on, stepped one more frame, and keyed it back off.

Repeat this process for each ghost frame you want to do, and that's it!

If you step through the animation, you can see where the real mesh is compared to its two ghosts by looking at where the rigging controls are. You can definitely use more ghosts per frame for faster movement. 3 meshes per real frame seemed to be the magic number for me this time.

To take things further, you could apply deformers to the ghost meshes like Henry appears to have done to squash/stretch and curve the rifle.

Hope this helps! big_smile

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