Abstract: A method and apparatus is disclosed for accurately determining the spatial orientation of planar and linear features expressed along the exterior surface of a core sample. The core sample is positioned in a plurality of sequentially generated orthogonal electromagnetic fields. The core sample is retained by a device which allows complete rotation of the core sample about a predetermined axis while positioned in the electromagnetic fields. A stylus containing an antenna for detecting the electromagnetic fields is used to trace surficial features along the core exterior while simultaneously detecting components of the generated electromagnetic fields. The stylus provides an output to an analyzing device which calculates the coordinates of points along the core features. The coordinates are passed to a computer which has also been monitoring the rotation angle of the core.