Tutorial 9: Animating a Multilegged Creature

Lesson 1: Animating a Quadruped with Freeform Animation

You'll use the same techniques you used in Animating a Freeform Walk Cycle, constraining both feet and the hands, and animating the pivot points. You'll lock the hands and feet at certain keys so you can adjust the biped's center of mass and spine to create your basic poses.

You'll learn to animate a character that leaps on all fours, but also can walk upright on two legs.

Setup

Saving a .fig file

  1. Select the biped, then open the Motion panel.

  2. Turn on Figure mode.

  3. Save a .fig file of the biped as mybeetle1.fig.

    This preserves the beetle's original pose.

  4. Turn off Figure mode.

    The pose does not change, since the beetle isn't animated in this file.

Putting the beetle on all fours

  1. Turn on Animate.

    You'll use the Animate button instead of the Set Key buttons for the first pose.

  2. On the Track Selection rollout choose Body Rotation.

    This selects the center of mass and activates rotation.

  3. Rotate the center of mass approximately 80 degrees, so the biped is nearly horizontal.

    Rotate the root (Bip01)

    The next steps rotate the arms and legs into position.

  4. In the Left viewport, draw a small selection box through the middle of the thighs.

    This selects both thighs in a single move.

  5. Right-click and choose Rotate.

  6. Rotate the thighs approximately 120 degrees about the Z axis.

  7. Press PAGE DOWN to move down the chains.

    This selects the calves.

  8. Rotate the calves so they are nearly horizontal and the feet are behind the biped.

    You'll add a couple of rotations to the arms now.

  9. In the Top viewport, select Bip01 R Clavicle. Hold down the CTRL key and click the Bip01 L Clavicle.

    Both clavicles are selected.

  10. In the Top viewport rotate the clavicles about the Y axis, approximately 40 degrees.

  11. Press PAGE DOWN to select both upper arms.

  12. Rotate the arms approximately -90 degrees about the X axis, so the palms are parallel to the ground.

  13. Rotate the arms approximately 90 degrees about the Z axis, so the arms stretch out in front of the biped.

  14. Rotate the arms about the Y axis, until they hang down.

  15. Rotate the arms about the Z axis so they move away from the body a bit more.

    Rotate the arms down.

  16. Press PAGE DOWN twice to select the hands.

  17. Rotate the hands so they are parallel to the ground.

  18. Tip: Zoom in so you don't select the fingers by accident.

  19. Rotate the head up, so the biped is looking straight ahead instead of downwards.

  20. Rotate the toes so they are flat on the ground. If necessary, rotate the foot, then the toes, so the feet and toes point forwards.

    Watch the Perspective viewport as you rotate.

    Make any additional adjustments to the legs, arms, spine, and so on until your model resembles the one illustrated here. Look at the beetle from several views, or rotate around it in the Perspective viewport.

    The beetle down on all fours

    If the beetle's posture is incorrect, open cs3_tut09_quad2.max to compare.

Changing Dynamic Blend and Balance Factor

You'll need to turn off Balance Factor and Biped Dynamics before you begin this freeform animation. These are settings that add secondary motion to footstep animation, which assumes the biped is walking upright.

For the beetle traveling on all fours, you'll turn off Balance Factor and Dynamics Blend.

  1. Open cs3_tut09_quad2..max.

  2. Be sure Animate is still on.

  3. Select the Body Horizontal Track.

    This selects the center of mass and turns on Move.

  4. On the Key Info rollout in the Body Dynamics group, change the Balance Factor from 0 to 1.

    In the Perspective viewport, the center of mass jumps from the pelvis to the area under the chest.

  5. Change the Balance Factor to 2.

    The center of mass jumps to the area under the throat.

    Balance Factor 2

  6. Change the Balance Factor back to 0.

    This will ensure that the hips and spine balance around the pelvis area.

    Balance Factor 0

    In this file, the Balance Factor was already set to 0.

  7. In the Track Selection rollout, choose Body Vertical.

  8. Set Dynamics Blend to 0.

    Tip: You can also access Balance Factor and Dynamic Blend from track bar keys for Body Horizontal and Body Vertical. Just Right-click on the key and choose the either from the list. You'll find Balance Factor at the bottom of the Body Horizontal key dialog, Dynamics Blend at the bottom of the Body Vertical dialog.

    For another tutorial that teaches about Balance Factor, see Tutorial 4, Lesson 4: Creating the Illusion of Weight.

Adding a ground plane

In the tutorial Animating a Freeform Walk Cycle, you set keys that locked the feet to the ground. These keys locked the feet to the world rather than to an object.

In this tutorial, you'll create a box and lock the beetle's feet to the object instead of locking them to the world.

  1. Zoom out of the Top viewport so the biped is smaller.

  2. In the Create panel, choose Box01.

  3. Create a box beneath the beetle. In the Top viewport, start at the top left and drag down to the lower right. After you click, continue to drag down to create a negative height for the box.

    Make the box 500 units in length, 100 units in width and any negative height.

    Biped and box

  4. In the Perspective viewport, select any part of the biped.

  5. In the Motion panel, choose Body Vertical in the Track selection rollout.

  6. Move the biped up and down in the viewport.

    The biped passes through the box.

  7. Right-click on the Left viewport. Press W to maximize it.

  8. Move the biped down so its hands and feet are in contact with the box.

    Zoom in to see the effect. Adjust the bipeds hands and feet if they are uneven.

    Biped positioned on box

Locking down the hands and feet

  1. Open cs3_tut09_quad_and_box.max.

    This file is like the one you've been working on, but the feet have been rotated so the heels are flat on the ground.

  2. Turn Animate on.

  3. Change the Perspective viewport to Wireframe and zoom in so you can see the hands and feet.

  4. Select the green Bip01 R Foot.

  5. In the IK Key Info rollout, choose Set Key.

    The pivot point is on the ball of the foot. You can leave it there.

  6. At the bottom of the IK Key Info rollout, click the Select Object Space Object arrow. Click the box in the viewport.

    The name Box01 is displayed in the rollout.

  7. In the IK Key Info rollout, choose Set Sliding Key.

  8. Select Bip01 L Foot and set another key.

  9. Select Box01 again, and set a sliding key.

    The feet are now locked to the box.

    Warning: You must set the Object Space Object before you set an IK Key. Otherwise the IK key parameters will be reset to IK Blend of zero and Body Space on. Also note that you can define only one object space object. You can not keyframe from one object space object to another.

  10. Select the Body Vertical track and move the center of mass up and down.

    The knees bend with the movement. The feet don't go through the box.

  11. Repeat these steps again for the left and right hands.

    The hands and feet act the same. Both are locked and do not pass through the box.

    Knees and elbows bend when the center of mass moves.

Adding Anticipation

Before a character jumps, you must prepare for the jump. To show anticipation a character moves in the opposite direction from the jump, and holds the pose, as if to tell the audience that something is about to happen.

  1. With Animate still on, move to frame 10.

  2. In the Track Selection rollout, choose Body Rotation.

  3. In the Left viewport, rotate the center of mass so the chin is almost touching the ground.

  4. Move the center of mass back so the elbows lower almost to the ground.

  5. Rotate the head so it's looking up.

  6. Add extra rotations to the Spine objects so the spine arches.

  7. Raise the center of mass if the elbows pass through the box.

    Pose at Frame 10

  8. Move the time slider back and forth between frames 0 to 10 and observe the motion.

  9. Save your work as myquad1.max.

Continuing the motion

You'll continue the motion at frame 20. You'll adjust the timing after you get all the poses in place.

  1. Move the time slider to frame 20.

  2. In the Track Selection rollout, choose Body Vertical.

  3. Lower the center of mass so the beetle crouches down.

  4. Select the biped spine elements (Bip01 Spine through Bip01 Spine03).

  5. Rotate the spine links.

  6. Rotate the upper spine links.

    Make your biped match the illustration.

    Pose at Frame 20

    Next, you'll animate the pivot points and rotate the feet so they roll from the heel to the toe. You'll rotate the hands so they rock from wrist to palm to fingertips.

Rotating the feet

  1. With Animate still on, move to frame 23.

  2. Select Bip01 R Foot.

    The pivot is displayed.

  3. Set a sliding key.

    Now you can select a pivot.

  4. Select the pivot at the ball of the foot and set a planted key.

    The pivot is locked at that frame.

  5. Turn off Select Pivot and right-click on the foot, then choose Rotate.

  6. Rotate the foot, so the heel is raised.

    If you look closely you will see the foot pop back. The reason this is happening is that the IK solution is giving the knee precedence over the ankle. To stop this pop, you'll need to change the Ankle Tension.

  7. Go to frame 0.

  8. In the IK Key Info, set the Ankle Tension to 1, and set a Planted Key.

  9. Now move the time slider back and forth and you will see the correct rotation.

  10. Go to frame 27.

  11. In the IK Key Info rollout, click set planted key.

  12. Click Select Pivot and select the pivot at the front and center of the toes.

    You may have to zoom in to see it.

    Selecting the pivot automatically sets a key for it. You don't have to choose set planted again.

  13. Turn off Select Pivot.

  14. Move the time slider to frame 30 and rotate the foot.

    The foot now rotates off the toe.

Rotating the hands

  1. With Animate still on, move the time slider to frame 23.

  2. Select the green Bip01 R Hand and set a planted key.

    The pivot is displayed and locked at frame 23.

  3. Rotate the hand, so the heel of the palm is raised.

    The fingers rotate downwards unlike the toes. You'll have to rotate the fingers to correct this.

  4. Select the fingers and rotate them upwards, so they don't go through the surface of the box.

    Since Animate is still on, you don't have to set keys for the fingers after you rotate them.

  5. Select the hand again, move the time slider to frame 27, and set a sliding key.

  6. Choose Select Pivot and select the pivot in the front and center of the fingers.

  7. Turn off Select Pivot.

  8. Rotate the hand.

    The hand rolls up, with only the fingertips touching the ground.

    Tip: If the hand doesn't rotate around the new pivot, reassign the Box01 as Object Space Object and rotate again. This time it will.

  9. Repeat the same procedures for the opposite set of limbs.

  10. At frame 30 move the center of mass up and forward so the beetle is just leaving the ground.

    Pushing off pose

  11. Save your work to myquad2.max.

Flying in the Air

When the beetle sails through the air, you'll use free keys on the hands and feet. No IK blend is needed.

  1. Turn on Animate, and move to frame 40.

  2. Set free keys for each foot and hand. With Move or Rotate active in the Main toolbar, click a hand or foot and, in the IK Key Info rollout, click Set Free Key.

    This sets IK Blend to 0 at frame 40 for the extremities.

  3. Select the center of mass and raise the biped up and to the right.

    The hands and feet are now off the box and the biped is in the air.

  4. Select the Bip01 R Foot, and move it so the legs extends fully.

  5. Extend the left leg the same way.

    The knees are no longer bent.

  6. Select both feet, and rotate them downwards and backwards.

  7. Press PAGE DOWN to select the toes and rotate them as well.

  8. Select both the hands and rotate them downwards and backwards.

  9. Select and rotate Bip01 Spine (the first spine object) so the biped straightens up.

  10. Rotate each spine objects individually. Go up through the spine, rotating each object, then rotate the first object again.

    This will remove the swayback in the spine.

  11. Rotate the head so the beetle looks ahead.

    Flying-into-air pose

Creating the top of the jump pose

The character is almost floating, reaching the height of his jump. You'll rotate the spine to hunch him over, tuck his elbows back, and bend his knees.

  1. At frame 56, on the Track Selection rollout, click the Body Vertical track.

  2. Move the biped up and over to the height of his jump.

    Move center of mass to height of jump.

  3. Select Bip01 Spine and rotate it so the biped bends forward.

  4. Press PAGE DOWN to select Bip01 Spine01.

  5. Deselect the thighs, then rotate the selected spine link.

  6. Continue moving and rotating each biped spine object.

  7. Rotate the head so the pose is more natural.

  8. Select both biped upper arms, and rotate them so the elbows are closer to the chest.

  9. Press PAGE DOWN to select both biped lowerarms, and rotate them so the fingers are near the biped's chin.

  10. Select both thighs and rotate them so the feet kick back.

  11. If you like, you can select both feet and then move them to tuck under the tail a little.

    Top of jump pose

Nearing the Ground Pose

You'll continue the biped's descent to the ground.

  1. At frame 72, with Animate still on, move the beetle downwards and to the right.

  2. Select the first three Bip01 Spine objects and rotate them downwards until the biped 's shoulders are pointing at the ground.

  3. Select only Bip01 Spine 2 and rotate about the Z axis until the biped's back straightens.

  4. Select both upper legs and rotate them.

  5. Rotate the lower legs.

  6. Select both hands and move them so they are outstretched.

    You can position the limbs using forward rotations (as you just did with the legs), or with inverse kinematics moves (as you just did with the hands).

    Arms extended to touch the ground

Creating the Landing Pose

The beetle will land at frame 85. You'll lock down the hands and adjust the center of mass.

  1. Move the time slider to frame 85.

  2. Select and move the center of mass so the fingers touch the box.

  3. Select both feet and move them outwards and up so the legs extend behind and above the biped.

  4. Rotate the feet so the toes point skywards.

  5. Move the time slider back and forth and watch the motion.

    You've created a little kick with the legs.

Rotating the hands

Rotate the hands up so the beetle doesn't break his fingers when he lands.

  1. At frame 93, select and rotate one hand so it is parallel to the ground.

  2. Rotate the other hand in the same way.

  3. Move the center of mass so the biped's hands are touching the box.

    Next you will lock down the pivot points.

  4. Select one hand and set a sliding key.

    Now you can set a key to lock the pivot.

  5. Choose Select Pivot, click on the pivot at the wrist and set a sliding key.

  6. Move the center of mass down so the elbows are close to the ground.

    The hands should lock to the box and the elbows should bend in response to the movement.

  7. Move one hand in front of the other.

    This makes it look like the hands are hitting the ground independently.

    The hands don't land together

Adjusting the legs

  1. Select both thighs and rotate them so the legs are under the beetle.

  2. Press PAGE DOWN twice to select both feet, then rotate them so the feet prepare to contact the ground.

  3. Press PAGE DOWN and rotate both toes until they are nearly horizontal.

  4. Select and move the center of mass so the toes are in contact with the ground.

  5. Move one foot backwards and upwards slightly.

    When an animal lands, its feet don't hit the ground at the same time.

  6. Rotate Bip01 Spine01 to raise the elbows and upper body slightly.

    Hitting the ground pose

  7. Select both feet and move the time slider to frame 91.

  8. Move the feet so the beetle compresses as he lands.

    The feet should be tucked under the tail.

Creating the Last Pose

  1. At frame 94 select one hand and set a planted key.

  2. Select the pivot on the wrist.

  3. Select the other hand and set a planted key.

  4. Select the pivot on the wrist.

  5. Select one foot and set a planted key.

  6. Select the pivot at the ball of the foot.

  7. Select the other foot and set a planted key.

  8. Select the pivot at the ball of the foot.

  9. Rotate the spine so the arms straighten out and the shoulders raise up a bit.

    Last Pose

  10. Save your work to myquad2.max.

Adjusting the timing

The take off and landings are too slow. Use the keys in trackbar to improve the timing.

  1. Select the entire biped.

    The keys displayed in the trackbar are the keys for the entire animation.

    There is too much time between frames 30 and 40.

  2. Select the keys from 72 through 100 by dragging a selection rectangle around them in the trackbar.

  3. Slide the selected keys so the key that was at frame 72 is now around frame 60.

  4. Select the keys from frame 40 through the end of the animation.

  5. Slide these keys so the key that was 40 is now around frame 33.

  6. Move the time slider back and forth.

    The take off and landing is much quicker.

  7. Save your work as myquad3.max.

    To compare your work to the finished animation, load cs3_tut10_quad_finished.max.

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