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July 29, 2005

What Would Ray Harryhausen Do?

by sven at 3:55 pm

Actual totals this week: Tues 8hrs, Weds 11hrs, Thurs 8hrs. This morning I started having little chest pains. ...Didn't I say walking is mandatory?

New regimen: 10min walk to the top of the big hill and back every two hours. Mustn't get hurt by throwing myself pendulum-style in the opposite direction, doing a huge 5 mile walk when I've let myself get this out of shape. Incentive: there are blackberries on the final descent. ...And I've got a second kitchen-timer running now to remind me to go.

exterior extablishing shot

Did a smart thing yesterday: had a LightWave scene ready to go, and set it rendering while I ate breakfast. I'd only had 2 seconds of the exterior establishing shot, which I looped. Now I've got a 5sec clip to work with.

hive - with distortion

hive - without distortion

The 4hr render of the hive that I ran Thursday night came out great! It was the right decision to not wrestle with the distortion around the lavamen just then, too. Friday morning I got the solution: What I needed wasn't transparency around the explorers, but rather a "clip map".

A clip map actually deletes bits of the image where you specify. Transparency (apparently) works differently. The way I figure it, transparency's algorithms are built to blend a semi-opaque foreground image with its background. So, even if the image is 100% transparent, the machine is still trying to do blending. That's where my distortion came from!

Now I've got better arms on the critters, the lavamen's feet don't slide on the floor, and there's not a lick of distortion. Excellent...

first draft "evil eye"

In the evening I moved on to working on the "evil eye" shot. Notice in my first draft that there's gaping to the right of the foremost eyestalk.

second draft "evil eye"

In this second draft I had some initial success, followed by a bunch of frustration.

I got the gaping to stop. What I did was to take all the points along the seams of the one-fifth critter and transform them into tiny little bones in a second layer. When I import those bones into Layout, they act like little pins, keeping the sides in place. ...Ah, but if you look below the eyestalk, now it's not bending as smoothly. Too much is being held in place, so there's creasing.

[In the second draft I also explored having the eyes rotate in their sockets. Too crazy, too much motion. I'm thinking that the eyes should be able to rotate in their sockets, but have very limited motion. It makes sense to me that if you have movable eyestalks, your actual eyeballs wouldn't have a lot of range on their own -- I mean, where would the musculature go? It's like a slug's eyes... But there are eyelids, so not exactly.]

What to do about the creasing? My first idea was to try to take the skeleton and put it inside another skin -- a full creature, rather than just a fifth. Problem: you can replace a skeleton's skin with another skin, but you can't just delete the skin altogether and do what you want with the bones. As Layout so eloquently states in its error message: "bones must remain under object they belong to". Sigh.

That failure led to me exploring what would happen if I created a full armature for the complete creature. I get a nightmare of 350 bones to keep track of -- that's what happens. Let me tell ya: it's difficult managing just a leg, arm and eyestalk at the same time. Trying to keep track of 15 wiggly bits is really impossible. You keep accidentally selecting the wrong bone and screwing up the whole scene when you move it. Layout (grrr grrr grrr) doesn't seem to have an "undo" button.

I went online and hunted for how other animators have dealt with tentacles. Three hours later my discovery: everyone who has attempted tentacles is flailing and begging for help. Lightwave 7.5 may not even be built for the task! ...There are a few plug-ins that may or may not help. There's a new book on character animation that claims to have a discussion on different types of tentacle motion (must find that!), there's a strategy for animating snakes that involves using "wind" to make them billow.

No silver bullet, though. What I'm left with is my previous conclusion: tentacles shouldn't just wiggle wildly -- they should be articulate, and they should roll in waves. That means articulating each of the ~25 bones in the arm or leg individually. Which, y'know, is what the old masters had to do.

But then it hits me: In working with the octopus from "It Came From Beneath The Sea", Ray Harryhausen cut off two tentacles, just to simplify things. Ray balked at eight.

...Oh. My critters have not six, but 15 wiggly bits. And everyone seems to agree that tentacles are the just about the toughest thing imaginable to animate. And this is my first ever attempt at 3D animation. WHAT AM I THINKING??

Called it quits and went to bed. ...At which point inspiration strikes.

Really, I've got three issues that I'm trying to work out simultaneously:

  1. I don't want there to be gaps between segments of the critter
  2. I want the motion of limbs to be reusable
  3. I need an easy way to choose bits of the limbs and grab them for posing

Well, I had a partial solution with my "pins" strategy. What if I took it farther? What if I chopped the one-fifth critter in three: leg, arm, eyestalk? Each critter would be made out of 15 pieces, each saved with its motion in a lws file. I could mix and match motions, assembling a a whole creature out of 15 bits, all parented together.

The torso wouldn't be able to bend. But -- and this is the second half of the inspiration -- I should be able to manage creasing issues with weight maps! Except for the seams, I should be able to make everything flexible.

Furthermore, I've been bothered by how the one-fifth critters seams look too sharply... Maybe I can create a full critter, and then chop it into bits to pose? If I stagger my cuts, they don't have to fall in the creases between fifths. Hopefully the pins will keep subpatch from making the edges of my critter pieces too wacky.

Wow... I might even be able to create a special waist-down rig with IK legs that would allow me to lift the body off the ground. Seeing the Elder Things stand up: that's what I want for Christmas!

Moral of the story: When people advocate "thinking outside of the box", they seldom talk about how you have to thoroughly explore every corner first, and then knock your head against the cardboard's weak spot repeatedly until you break through.

Now, on to today's work...

posted by sven | July 29, 2005 3:55 PM | categories: let sleeping gods lie, movies