Gordon Collins

From 3D shape capture of animated models

This paper presents a framework for construction of animated models from captured surface shape of real objects. Algorithms are introduced to transform the captured surface shape into a layered model. The layered model comprises an articulation structure, generic control model and a displacement map to represent the high-resolution surface detail. Novel methods are presented for automatic control model generation, shape constrained fitting and displacement mapping of the captured data. Results are demonstrated for surface shape captured using both multiple view images and active surface measurement. The framework enables rapid transformation of captured data into a structured representation suitable for realistic animation.

Animated statues

Abstract.In this paper we present a layered framework for the animation of high-resolution human geometry captured using active 3D sensing technology. Commercial scanning systems can now acquire highly accurate surface data across the whole-body. However, the result is a dense, irregular, surface mesh without any structure for animation. We introduce a model-based approach to animating a scanned data-set by matching a generic humanoid control model to the surface data. A set of manually defined feature points are used to define body and facial pose, and a novel shape constrained matching algorithm is presented to deform the control model to match the scanned shape. This model-based approach allows the detailed specification of surface animation to be defined once for the generic model and re-applied to any captured scan. The detail of the high-resolution geometry is represented as a displacement map on the surface of the control model, providing smooth reconstruction of detailed shape on the animated control surface. The generic model provides animation control over the scan data-set, and the displacement map provides control of the high-resolution surface for editing geometry or level of detail in reconstruction or compression.

Models for character animation

GORDON COLLINS and ADRIAN HILTON present a review of methods for the construction and deformation of character models. They consider both state of the art research and common practice. In particular they review applications, data capture methods, manual model construction, polygonal, parametric and implicit surface representations, basic geometric deformations, free form deformations, subdivision surfaces, displacement map schemes and physical deformation. Copyright

Coherent anti-Stokes Raman scattering of laser shock compressed α-quartz

We have developed the capability to perform in situ coherent anti-Stokes Raman scattering (CARS) spectroscopy on materials that are dynamically compressed using the Janus laser at Lawrence Livermore National Laboratory. We measured the CARS spectrum of α-quartz that was shocked above the Hugoniot elastic limit along the c-axis to 19.0 GPa. These data show that the Si-O-Si angle, which is natively 144° becomes a distribution of angles ranging from 139° to 146°. The data also observe a significant increase in the broad peak above 600 cm-1 that is attributed to defects in amorphous silica. Previous studies have shown these features in shock recovered α-quartz samples that have undergone varying amounts of amorphization, and these data show strong evidence of amorphization of quartz at a pressure below that of the amorphization observed in the shock-recovered samples.

Spatio-temporal fusion of multiple view video rate 3D surfaces

We consider the problem of geometric integration and representation of multiple views of non-rigidly deforming 3D surface geometry captured at video rate. Instead of treating each frame as a separate mesh we present a representation which takes into consideration temporal and spatial coherence in the data where possible. We first segment gross base transformations using correspondence based on a closest point metric and represent these motions as piecewise rigid transformations. The remaining residual is encoded as displacement maps at each frame giving a displacement video. At both these stages occlusions and missing data are interpolated to give a representation which is continuous in space and time. We demonstrate the integration of multiple views for four different non-rigidly deforming scenes: hand, face, cloth and a composite scene. The approach achieves the integration of multiple-view data at different times into one representation which can processed and edited.

Mesh Decimation for Displacement Mapping

We present a mesh decimation algorithm for triangular meshes. Unlike other decimation algorithms we are not concerned with geometric error but with the existence of a displacement mapping which can map between the original and decimated meshes. We use the implicit function theorem to derive a condition which ensures the existence of a displacement map. The algorithm is applied to some standard scanned models and reduction rates around 99% are seen.