• Title/Summary/Keyword: 완전파형역산

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Evaluating Accuracy of Algorithms Providing Subsurface Properties Using Full-Reference Image Quality Assessment (완전 참조 이미지 품질 평가를 이용한 지하 매질 물성 정보 도출 알고리즘의 정확성 평가)

  • Choi, Seungpyo;Jun, Hyunggu;Shin, Sungryul;Chung, Wookeen
    • Geophysics and Geophysical Exploration
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    • v.24 no.1
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    • pp.6-19
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    • 2021
  • Subsurface physical properties can be obtained and imaged by seismic exploration, and various algorithms have been developed for this purpose. In this regard, root mean square error (RMSE) has been widely used to quantitatively evaluate the accuracy of the developed algorithms. Although RMSE has the advantage of being numerically simple, it has limitations in assessing structural similarity. To supplement this, full-reference image quality assessment (FR-IQA) techniques, which reflect the human visual system, are being investigated. Therefore, we selected six FR-IQA techniques that could evaluate the obtained physical properties. In this paper, we used the full-waveform inversion, because the algorithm can provide the physical properties. The inversion results were applied to the six selected FR-IQA techniques using three benchmark models. Using salt models, it was confirmed that the inversion results were not satisfactory in some aspects, but the value of RMSE decreased. On the other hand, some FR-IQA techniques could definitely improve the evaluation.

Frequency domain elastic full waveform inversion using the new pseudo-Hessian matrix: elastic Marmousi-2 synthetic test (향상된 슈도-헤시안 행렬을 이용한 탄성파 완전 파형역산)

  • Choi, Yun-Seok;Shin, Chang-Soo;Min, Dong-Joo
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.06a
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    • pp.329-336
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    • 2007
  • For scaling of the gradient of misfit function, we develop a new pseudo-Hessian matrix constructed by combining amplitude field and pseudo-Hessian matrix. Since pseudo- Hessian matrix neglects the calculation of the zero-lag auto-correlation of impulse responses in the approximate Hessian matrix, the pseudo-Hessian matrix has a limitation to scale the gradient of misfit function compared to the approximate Hessian matrix. To validate the new pseudo- Hessian matrix, we perform frequency-domain elastic full waveform inversion using this Hessian matrix. By synthetic experiments, we show that the new pseudo-Hessian matrix can give better convergence to the true model than the old one does. Furthermore, since the amplitude fields are intrinsically obtained in forward modeling procedure, we do not have to pay any extra cost to compute the new pseudo-Hessian. We think that the new pseudo-Hessian matrix can be used as an alternative of the approximate Hessian matrix of the Gauss-Newton method.

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