A method, comprising: interrogating a human target with interrogation electromagnetic radiation including one or more frequencies in a range of about 1 GHz to about 1 THz by way of a sensing array configured to transmit interrogation electromagnetic radiation and to receive electromagnetic radiation reflected from the human target; establishing spatially varying data in potentially ambiguous image data sets corresponding to a three-dimensional representation of a surface of the human target based on detected portions of the reflected electromagnetic radiation corresponding to a plurality of overlapping arc segments (S1-S8) that collectively circumscribe the human target, wherein the spatially varying data corresponds to a positional uncertainty of the surface in a selected cross-sectional region of the representation; and generating a three-dimensional point cloud representation of the surface so as to represent a surface contour, the point cloud representation including a number of points each determined by evaluating spatial variations of the spatially varying data for different overlapping arc segments (S1-S8) along a corresponding one of a number of reference axes extending through the cross-sectional region, with a distance along the reference axis representing a relative position from which a reflected electromagnetic signal was returned and a magnitude of the reflected electromagnetic signal returned from each position along the reference axis being analysed so as to allow discrimination between reflected electromagnetic signal magnitude peaks above a threshold value and background noise so as to determine a likely position of the surface in the cross-sectional region; wherein either: i) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a line segment coplanar with the sectional plane, and at least a portion of the reference axes are approximately parallel to one another; or ii) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a radial line segment extending from an origin and coplanar to the sectional plane, and the contour at least partially surrounds the origin. interrogating a human target with interrogation electromagnetic radiation including one or more frequencies in a range of about 1 GHz to about 1 THz by way of a sensing array configured to transmit interrogation electromagnetic radiation and to receive electromagnetic radiation reflected from the human target; establishing spatially varying data in potentially ambiguous image data sets corresponding to a three-dimensional representation of a surface of the human target based on detected portions of the reflected electromagnetic radiation corresponding to a plurality of overlapping arc segments (S1-S8) that collectively circumscribe the human target, wherein the spatially varying data corresponds to a positional uncertainty of the surface in a selected cross-sectional region of the representation; and generating a three-dimensional point cloud representation of the surface so as to represent a surface contour, the point cloud representation including a number of points each determined by evaluating spatial variations of the spatially varying data for different overlapping arc segments (S1-S8) along a corresponding one of a number of reference axes extending through the cross-sectional region, with a distance along the reference axis representing a relative position from which a reflected electromagnetic signal was returned and a magnitude of the reflected electromagnetic signal returned from each position along the reference axis being analysed so as to allow discrimination between reflected electromagnetic signal magnitude peaks above a threshold value and background noise so as to determine a likely position of the surface in the cross-sectional region; wherein either: i) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a line segment coplanar with the sectional plane, and at least a portion of the reference axes are approximately parallel to one another; or ii) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a radial line segment extending from an origin and coplanar to the sectional plane, and the contour at least partially surrounds the origin. i) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a line segment coplanar with the sectional plane, and at least a portion of the reference axes are approximately parallel to one another; or ii) the cross-sectional region corresponds to a sectional plane, the reference axes each correspond to a radial line segment extending from an origin and coplanar to the sectional plane, and the contour at least partially surrounds the origin.