Confirmation of the ScanPyramids North Face Corridor in the Great Pyramid of Giza using multi-modal image fusion from three non-destructive testing techniques

While non-destructive testing (NDT) measurements have been reported individually for archeological surveys of cultural heritage structures, only a few studies to date have attempted to combine NDT images by means of image fusion (IF). In this article, novel multimodal IF results from three different NDT techniques collected at the Chevron located on the Great Pyramid of Giza (aka. as Khufu's Pyramid) are presented. The Chevron is an assembly of limestone blocks located in front of the recently confirmed ScanPyramids North Face Corridor (SP-NFC), which had been previously hidden for 4500 years. Under the research activities of the ScanPyramids mission, three profiles located on the Chevron were selected to explain multimodal IF in detail and highlight its usefulness in archeology. The NDT techniques employed in this study include ground penetrating radar (GPR), ultrasonic testing (UST), and electrical resistivity tomography (ERT). A discrete wavelet transform (DWT)-based algorithm was employed to merge the reconstructed images from the three techniques for each profile, producing a single composite image. The final fused images contain pertinent information from all modalities, allowing to validate assumptions used to create the individual reconstructed images, and enable a more detailed examination of some of the conclusions reached in the authors' previous ScanPyramids work.