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Table of Contents

New Digitizing Techniques:
MALLISON, HOHLOCH, & PFRETZSCHNER

Plain-Language &
Multilingual  Abstracts

Abstract

Introduction

Materials

General Outline of Mechanical Digitizing Methods

Extracting Virtual Bones from
CT Data

Accuracy of Mechanical Digitizing Data

Benefits and Limitations of Mechanically Digitized Data

Conclusions

Acknowledgements

References

Appendix A

Appendix B

Appendix C

Appendix D

Appendix E

 

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CONCLUSIONS

Mechanical digitizing with a Microscribe 3D digitizer provides a cheap and easy alternative to complicated high-resolution digitizing techniques such as CT scanning and laser scanning, at an accuracy sufficient for most research and curatorial tasks. The accuracy of mechanical digitizing data is comparable to CT data of similar file sizes. Mechanical digitizing provides a far superior database for digital 3D skeleton creation than photographs, measurements, or drawings of bones.

We find that for medium accuracy or complex topographies, point cloud based digitizing works best, while very large objects can be rapidly digitized at slightly lower accuracy using NURBS curves. Costs are much lower than CT or laser scanning, especially if only NURBS elements are used, while point cloud digitizing requires one additional computer program. The main cost factor, however, is the digitizer. The work time requirements are comparable or below those of high-detail techniques. A custom-made and adjustable holder for specimens eases the workload of digitizing significantly, by allowing 360° access.

Mechanical digitizing data can easily be shared by email or on websites with other researchers around the world. Computing power requirements and post-digitizing workload are comparatively low, when using our methods for NURBS digitizing, and all equipment is easily transported in a single suitcase. Thus digitizing can take place in collections worldwide. Transport of specimens to hospitals or other institutions with CT scanners is not required. The risk of loss and damage to specimens is reduced somewhat. However, the digitizing process itself increases the risk of damage more than CT or laser scanning, and thus excludes the use of the techniques on fragile specimens.

The biggest drawbacks of mechanical digitizing are the inability to acquire color data and the limited resolution. However, we found that the resolution is nearly comparable to CT scan-based data at similar overall file sizes.

Three-dimensional digital files can be used for a wide variety of research studies, including ontogenetic and biomechanical aspects, and are useful for museum display and curatorial aspects. However, data from mechanical digitizing is limited to reproduction of the general shape of bones, not high resolution surface detail such as rugosities. Delicate structures, especially thin edges below 2 mm thickness, may be significantly deformed in the digital files, and internal surfaces can not be depicted at all. Also, post-digitizing file editing can consume additional time. These factors should be kept in mind before projects based on mechanically digitized data are planned.

 

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New Digitizing Techniques
Plain-Language & Multilingual  Abstracts | Abstract | Introduction | Materials
General Outline of Mechanical Digitizing Methods | Extracting Virtual Bones from CT Data
Accuracy of Mechanical Digitizing Data | Benefits and Limitations of Mechanically Digitized Data
Conclusions | Acknowledgements | References |
Appendix A | Appendix B | Appendix C | Appendix D | Appendix E
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