Computing and Retrieving 3D Archaeological Structures from Subsurface Surveying

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Today's archaeological excavations are slow and the cost for conservation can easily exceed the cost of excavation. This project is investigating and developing methods for the recovery of 3D underground structures from subsurface non-invasive measurements obtained with ground penetrating radar, magnetometry, and conductivity sensors. The results will not only provide hints for further excavation but also 3D models that can be studied as if they were already excavated. The three fundamental challenges investigated are the inverse problem of recovering the volumetric material distribution, the segmentation of the underground volumes, and the reconstruction of the surfaces that comprise interesting structures. In the recovery of the underground volume, high-fidelity geophysics models are introduced in their original partial differential equation form. Partial differential equations from multiple modalities are simultaneously solved to yield a material distribution volume. In segmentation, a graph spectral method for estimating graph cuts finds clusters of underground voxels with tight connections within partitions and loose connections between partitions. A method based on multi-scale graph cuts significantly accelerates the process while the grouping properties of the normalized cuts help in clustering together multiple fragments of the same material. In surface reconstruction, boundaries obtained from segmentation or from targeted material search are converted from unorganized voxel clouds to connected surfaces. A bottom-up approach is introduced that groups neighborhoods into facets whose amount of overlap guides the triangulation process. The archaeology PIs are providing prior knowledge on what structures are expected to be found which can lead the segmentation and the reconstruction steps.The geoscience and archaeology PIs lead the effort of data acquisition at the Tiwanaku site in Bolivia. All original data as well as recovered 3D models will be made available to the public.