RESOLUTION LIMITS IN RAY TOMOGRAPHY DUE TO WAVE BEHAVIOR - NUMERICAL EXPERIMENTS
RESOLUTION LIMITS IN RAY TOMOGRAPHY DUE TO WAVE BEHAVIOR - NUMERICAL EXPERIMENTS
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DOI：
10.1190/1.1443457
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发表时间：
1993-05-01
期刊：
影响因子：
3.3
通讯作者：
WORTHINGTON, MH
中科院分区：
文献类型：
--
作者：
WILLIAMSON, PR;WORTHINGTON, MH
有几个因素限制了射线层析成像获得的分辨率。其中，地球物理文献中讨论最少的是射线近似本身的影响；散射被忽略，地震道中包含的信息被减少到一个旅行时拾取。射线层析成像和衍射层析成像的频域比较表明，射线层析成像可分辨的最小特征尺寸约为第一菲涅耳区宽度的量级。我们用数值实验研究了时空域的分辨率。用有限差分程序生成了四个合成数据集，对应于两个孔间距和两个频率下的井间层析成像测量。然后，通过计算它们与原始模型的过滤版本的相似性以及从通过原始模型跟踪射线获得的数据集的重建来评估从这些层析图像中获得的分辨率的规模。结果广泛地证实了分辨率与菲涅耳区的关系。因此，这种对分辨率的限制可能至少与由于实验几何等其他因素造成的限制一样重要。
Several factors limit the resolution obtained in ray tomography. Of these the least thoroughly discussed in the geophysical literature is the effect of the ray approximation itself; scattering is ignored and the information contained in a seismic trace is reduced to one traveltime pick. Frequency domain comparisons of ray tomography with diffraction tomography have suggested that the minimum feature size resolvable by ray tomography is of the order of the width of the first Fresnel zone. We investigate resolution in the space-time domain with a numerical experiment. Four synthetic data sets were generated with a finite-difference program corresponding to crosshole tomographic surveys at two hole separations and two frequencies. The scale of resolution achieved in tomograms derived from these is then assessed by calculating their semblance to filtered versions of the original model and reconstructions from data sets obtained by tracing rays through the original models. The results broadly confirm the relation of resolution to Fresnel zones. It is therefore possible that such limits on resolution may be at least as significant as those due to other factors such as experimental geometry.