Earticle

초록

영어

Underwater archaeology relies heavily on photography and video image recording during surveillances and excavations like ordinary archaeological studies on land. All underwater images suffer poor image quality and distortions due to poor visibility, low contrast and blur, caused by differences in refractive indices of water and air, properties of selected lenses and shapes of viewports. In the Y ellow S ea ( between mainland China a nd t he Korean p eninsula), t he v isibility underwater i s f ar l ess than 1 m, typically in the range of 30 cm to 50 cm, on even a clear day, due to very high turbidity. For photographing 1 m x 1 m grids underwater, a very wide view angle (180o) fisheye lens with an 8 mm focal length is intentionally used despite unwanted severe barrel-shaped image distortion, even with a dome port camera housing. It is very difficult to map wide underwater archaeological excavation sites by combining severely distorted images. Development of practical compensation methods for distorted underwater images acquired through the fisheye lens is strongly desired. In this study, the source of image distortion in underwater photography is investigated. We have identified the source of image distortion as the mismatching, in optical axis and focal points, between dome port housing and fisheye lens. A practical image distortion compensation method, using customized image processing software, was explored and verified using archived underwater excavation images for effectiveness in underwater archaeological applications. To minimize unusable area due to severe distortion after distortion compensation, practical underwater photography guidelines are suggested.

목차

ABSTRACT
1. INTRODUCTION
2. MATERIALS AND METHODS
2.1. Underwater photographs
2.2. Underwater photography equipment
2.3. Image analysis software
3. RESULTS AND DISCUSSION
3.1. Origin of image distortion
3.2. Underwater photography
3.3. Requirement for underwater photography in limited visibility
3.4. Types of image distortion
3.5. Software-based distortion compensation
3.6. Discussion
4. CONCLUSION
REFERENCES

저자

• Young-Hwa Jung [ Kongju National University, National Research Institute of Maritime Cultural Heritage ]
• Gyuho Kim [ Kongju National University, Kongju 32588, Korea ]
• Woo Sik Yoo [ WaferMasters, Inc., Dublin, CA 94568, USA, Institute of Humanities Studies, Kyungpook National University, Daegu 41566, Korea ] Corresponding Author

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