Computing and Fabricating Multilayer Models

晃晃

Computing and Fabricating Multilayer Models

Michael Holroyd Ilya Baran Jason Lawrence Wojciech Matusik

University of Virginia Disney Research Z¨ urich University of Virginia MIT CSAIL  

Disney Research Z¨ urich

Abstract

We present a method for automatically converting a digital 3D

model into a multilayer model: a parallel stack of high-resolution

2D images embedded within a semi-transparent medium. Multi-

layer models can be produced quickly and cheaply and provide a

strong sense of an object’s 3D shape and texture over a wide range

of viewing directions. Our method is designed to minimize visi-

ble cracks and other artifacts that can arise when projecting an in-

put model onto a small number of parallel planes, and avoid layer

transitions that cut the model along important surface features. We

demonstrate multilayer models fabricated with glass and acrylic

tiles using commercially available printers.

CR Categories: I.3.3 [Computer Graphics]: Picture/Image

Generation—Display algorithms; I.3.5 [Computer Graphics]:

Computational Geometry and Object Modeling—Curve, surface,

solid, and object representation

Keywords: multilayer models, fabrication, volumetric displays

1 Introduction

We describe a method for converting digital 3D models into multi-

layer models. Our work is inspired by artists like Carol Cohen1

and

Dustin Yellin2

who reproduce three-dimensional forms by painting

on glass or acrylic sheets and then stacking them together (Fig-

ure 2). A multilayer model thus consists of a small number of high-

resolution 2D images stacked along the 3rd dimension, and creates

a natural 3D effect by displaying parts of the object at the appropri-

ate depth over a range of viewing directions.

There is no substitute for the experience of holding and examin-

ing a physical 3D object in your hands. Technologies capable of

manufacturing 3D objects have seen significant advances in recent

years, most notably 3D printing [Dimitrov et al. 2006] and multi-

axis milling. However, despite these advances, producing a 3D pro-

totype in full color remains expensive and time-consuming. Fur-

thermore, objects with thin features and disconnected parts (e.g.,

the tree in Figure 14) cannot be printed at all using existing tech-

niques. In contrast, a multilayer model (as in Figure 1) can be fab-

ricated in minutes and for a fraction of the cost and provides many

of the benefits of a physical replica.





The process of converting a 3D surface into a multilayer model re-

quires a number of algorithmic advances in order to produce high-

quality output. First, we observe that a na¨ ıve projection of the in-

put surface onto multiple parallel planes creates artifacts caused by

visible seams or cracks and salient features being split between dif-

ferent layers. We propose a novel algorithm that warps each layer

based on the way it is occluded by the layers above it in order to

avoid these seams while simultaneously seeking cuts along tex-

tureless regions. Second, the shadows that each layers casts onto

those below it can undermine the intended 3D effect. We describe a

fast method for computing a correction factor that compensates for

these shadows. Finally, one also needs to consider the contrast loss

caused by light absorption in the embedding medium (e.g., glass

or acrylic). We propose a simple measurement process to estimate

parameters of an analytic absorption model. Based on this model,

we restrict the colors printed on each layer to a reduced color gamut

that can be achieved throughout the volume.

We show multiple examples of multilayer models produced with

our prototype system. Additionally, we include a comparison of

our method to simple alternatives that illustrate the importance of

properly handling cracks, seams, self shadowing, and volumetric

attenuation. We believe multilayer models can serve as useful rapid

prototypes, teaching aids, art, and personalized memorabilia.











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菜刀吻电线

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晃晃

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奇

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晃晃

很有心,部分已收录自用,谢谢

晃晃

有意思！学习了！

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