The Monkey House

Most recently, we've been working on a new monkey model that includes polygon mesh bones and muscles, as well as the original ellipsoidal components. This model also includes a choice of fur types (line, polyline, nurbs curves, and nurbs surface). Further results in fur modeling can be seen on the Fur Page. Some Sample Monkey Animations are at the bottom of this page.

Bones, Muscles, Filler, and Skin

This image shows the four types of components. The upper left shows the skeleton, which is a combination of polygon mesh and ellipsoidal bones. The upper right shows polygon mesh and ellipsoidal muscles as well. The lower left includes generalized filler tissue modeled with ellipsoids. The lower right shows the overlying polygon mesh skin. (The image is 96 Kbytes.)



The Pectoralis and Quadriceps Muscle Models

This image shows the pectoralis (left) and the quadriceps muscle (right). The quadriceps is shown changing shape around a pivot when the knee bends. Muscles extend from two origin points to two insertion points, all fixed at parameterized locations on particular bones. They automatically change shape in a volume preserving manner during joint motion. (The image is 67 Kbytes.)



Voxelization, Filtering, and Skin Extraction

This image shows how the skin is extracted. 1. The underlying components are shown in a rest position, with the extremities enlarged for greater detail in the extraction (upper left). 2. A 3D grid over the body has been voxelized, with grid points inside the body given a different scalar value than those outside (upper right). 3. The volume is filtered for smoothness (lower left). 4. An isosurface skin is extracted (lower right). (The image is 61 Kbytes.)



Mohawk Monkey, Examples of Skin Repositioning

These images (187 and 30 Kbytes) show the skin over the monkey in various positions. The skin is attached to underlying components and moves with them, initially, when the body moves. Next, skin points are mapped to world space and adjusted using an elastic membrane model.




Repositioning Skin in Wireframe

This image shows the skin of the shoulder before elastic adjustment at left. Notice how the polygons are stretched far apart by the joint motion. At right, elastic adjustment has re-equilibrated the surface. (The image is 138 Kbytes.)




Repositioning Skin in Shaded Images

This image shows the bent back in the upper left. Note the folds in the skin. The other pictures show the shoulder skin at various joint positions. It is texture mapped so that each skin triangle has a circle mapped to it. When the skin moves, circles deform appropriately after adjustment. (The image is 118 Kbytes.)




Importance of Elastic Adjustment for Fur

This image shows the same shoulder region as the previous image but with fur. When the skin isn't elastically adjusted, the hairs are pulled far apart and leave gaps. When the skin is adjusted, the hairs are positioned properly. (The image is 104 Kbytes.)




Examples of Fur Modeling

This image shows various monkeys with fur. The fur model is relatively simple but quite fast. Parameters give control over density, color, length, curvature, gravity, etc. A paper describing the fur model will appear in Graphics Interface '97 in May. See also the Fur Page. (This image is 210 Kbytes.)

If you have patience, this image is available in a larger version (759 Kbytes).


Animations

_____ _____ _____
Shoulder Components __ Shoulder Skin ________ Monkey Skin 1 ________ Monkey Skin 2
Quicktime, 0.35 Mb ___ Quicktime, 0.38 Mb ___ Quicktime, 0.76 Mb ____ Quicktime, 0.98 Mb

_____ ______ _____
Leg Components______ Line Fur 1_____________ Line Fur 2___________
Quicktime, 0.7 Mb____ Quicktime, 1.5 Mb______ Quicktime, 1.2 Mb____