severely limited by less-than-ideal environmental conditions. Fine-grained sediments (clays and silts) are often problematic because their high electrical conductivity causes loss of signal strength; rocky or heterogeneous sediments scatter the GPR signal, weakening the useful signal while increasing extraneous noise. In the field of cultural heritage GPR with high frequency antenna is also used for investigating historical masonry structures, detecting cracks and decay patterns of columns and detachment of frescoes. Burial sites GPR is used by criminologists, historians, and archaeologists to search burial sites. In his publication, Interpreting Ground-penetrating Radar for Archaeology, Lawrence Conyers, who is "one of the first archaeological specialists in GPR" described the process. Conyers published research using GPR in El Salvador in 1996, in the Four Corners region Chaco period in southern Arizona in 1997, and in a medieval site in Ireland in 2018. Informed by Conyer's research, the Institute of Prairie and Indigenous Archaeology at the University of Alberta, in collaboration with the National Centre for Truth and Reconciliation, have been using GPR in their survey of Indian Residential Schools in Canada. By June 2021, the Institute had used GPR to locate suspected unmarked graves in areas near historic cemeteries and Indian Residential Schools. On May 27, 2021, it was reported that the remains of 215 children were found using GPR at a burial site at the Kamloops Indian Residential School on Tk’emlúps te Secwépemc First Nation land in British Columbia. In June 2021, GPR technology was used by the Cowessess First Nation in Saskatchewan to locate 751 unmarked gravesites on the Marieval Indian Residential School site, which had been in operation for a century until it was closed down in 1996. Advancements in GPR technology integrated with various 3D software modelling platforms, generate three-dimensional reconstructions of subsurface "shapes and their spatial relationships". By 2021, this has been "emerging as the new standard". Three-dimensional imaging Individual lines of GPR data represent a sectional (profile) view of the subsurface. Multiple lines of data systematically collected over an area may be used to construct three-dimensional or tomographic images. Data may be presented as three-dimensional blocks, or as horizontal or vertical slices. Horizontal slices (known as "depth slices" or "time slices") are essentially planview maps isolating specific depths. Time-slicing has become standard practice in archaeological applications, because horizontal patterning is often the most important indicator of cultural activities. Limitations The most significant performance limitation of GPR is in