Airborne geophysical survey: Piedmont Areas, Virginia

Aeromagnetic data were collected along flight lines by instruments in an
aircraft that recorded magnetic-field values and locations. In the earlier
days of surveying, the only way to represent this data was to generate an
analog map with contour lines. This dataset is a representation of the
digitized contour lines either by following the lines or by choosing the
intersection of the contour and flight-line to create a value of the magnetic
field. The values presented are latitude, longitude, and map magnetic-field
values.

航空磁测数据由飞行器搭载的探测仪器沿飞行航线采集，同步记录磁场强度值与位置坐标。在早期航空勘测阶段，此类数据仅能通过绘制带等值线的模拟地图进行呈现。本数据集是对数字化等值线的重构，可通过沿等值线逐点追踪采样，或通过求取等值线与飞行航线的交点来生成磁场强度数值。本次发布的数据包含纬度、经度与实测磁场强度值。