Based on Rick Parent’s - CIS681 slide set

Shape Deformoration

- Compressive bulging (e.g. muscles)- Folding and stretching (e.g. skin)- Draping

Physical Phenomena

Contortion for Expression

- Anthropomorphic form (e.g. Aladdin’s carpet)- Facial gestures

Based on Rick Parent’s - CIS681 slide set

Key Shapes

Mapping - Vertex to vertex - Edge to edge

Based on Rick Parent’s - CIS681 slide set

Global Deformations - taper

Based on Rick Parent’s - CIS681 slide set

Global Deformations - twist

x’ = s(z) · xy’ = s(z) · y z’ = z

Where s(z) = (maxz –z)

(maxz – minz)

Based on Rick Parent’s - CIS681 slide set

Global Deformations - twist

Based on Rick Parent’s - CIS681 slide set

Global Deformations - rotate

Based on Rick Parent’s - CIS681 slide set

Global Deformations - rotate

Based on Rick Parent’s - CIS681 slide set

Global Deformations - compound

Based on Rick Parent’s - CIS681 slide set

Skeletal Deformation

Based on Rick Parent’s - CIS681 slide set

Skeletal Deformation

Interior angle bisectors

Perpendiculars at end points

Based on Rick Parent’s - CIS681 slide set

Skeletal Deformation

d

L

s

Get object

Draw polyline

Map vertices to polyline

Warp polyline

Reposition vertices to polyline

Based on Rick Parent’s - CIS681 slide set

Skeletal Deformation

Based on Rick Parent’s - CIS681 slide set

Skin and BonesSkin mess surrounds bone structure

Jeff Lander’s IGDN notes

Problem: Folding at joints

Solution: Attach vertices to multiple bones Weight influence

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

2D technique used in the film HUNGER

Overlay 2D grid on top of object

Map object vertices to grid cells (create local coordinate system)

User distorts 2D grid vertices

Object vertices are remapped to local coordinate system of 2D grid by using bilinear interpolation

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

0.5

0.8

For each vertexIdenify cellLocal u,v coorindate

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

Bilinear interpolationPu0 = (1-u)*P00 + u*P10Pu1 = (1-u)*P01 + u*P11Puv = (1-v)*P0u + v*P1u

P00

P01

P01

P11

Pu0

Pu1

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

Based on Rick Parent’s - CIS681 slide set

Grid Deformation

Based on Rick Parent’s - CIS681 slide set

Free-Form Deformations

(not necessarily mutually perpendicular)

S

T

U

Define local coordinate system for deformation

Based on Rick Parent’s - CIS681 slide set

FFD - register point in cell

S

T

U

Based on Rick Parent’s - CIS681 slide set

FFD - register point in cell

s = (TxU) . (P-P0) / ((TxU) . S)

TxU U

S

T

P

P0

((TxU) . S) (TxU) . (P-P0)

P = P0 + sS + tT + uU

Based on Rick Parent’s - CIS681 slide set

FFD - create control grid

(not necessarily mutually perpendicular)

Based on Rick Parent’s - CIS681 slide set

FFD - move and reposition

Move control grid points

Usually tri-cubic interpolation is used with FFDs

Originally Bezier interpolation was used.

B-spline and Catmull-Romm interpolation have also been used (as well as tri-linear interpolation)

Based on Rick Parent’s - CIS681 slide set

Example of FFD

It is originally a cylinder. Red boundary is FFD block embedded with that cylinder

Step1

Step2

move control points of each end,and you can see cylinder insidealso changes.

From http://www.comp.nus.edu.sf/~cs3246/CS3246_01/anim4.ppt

Based on Rick Parent’s - CIS681 slide set

step3

move inner control points downwards.

step4

Finally, get the shaded version of banana!

From http://www.comp.nus.edu.sf/~cs3246/CS3246_01/anim4.ppt

Based on Rick Parent’s - CIS681 slide set

FFD - extensions

Hierarchical FFDs

Animation with FFD

- Move object through a deformation

- Interpolate deformed shape

- Interpolate deformation (i.e. control points)

Based on Rick Parent’s - CIS681 slide set

FFD – films, videos, and pictures

Alladin

Black and White, PDI

Tomoyuki Hishita's animations

Balloon Guy, Chris Wedge

Jason Weber Pictorial