GSNSW Exploration NSW Area G SE Darling Basin elevation line data

Digital Elevation Model data record the terrain height variations from the processed point-located data recorded on an airborne geophysical survey.� The aircraft altimeter data records the height of the aircraft above the ground and the aircraft GPS records the height of the aircraft above the ellipsoid.� Subtracting the two values enables the height of the terrain beneath the aircraft relative to the ellipsoid to be calculated.� This ellipsoidal terrain height is corrected for the variation between the ellipsoid and the geoid (the n-value correction) to produce terrain heights relative to sea level.

数字高程模型（Digital Elevation Model, DEM）数据依托航空地球物理勘探中采集并经处理的点位数据生成，用于记录地形高程起伏变化。机载高度计可记录飞行器距地面的高度，机载全球定位系统（GPS）则可获取飞行器距参考椭球面的高度；将两组数值相减，即可计算出飞行器正下方地形相对于参考椭球面的高程。随后对该椭球面地形高程开展参考椭球面与大地水准面（geoid）间的差值校正（即n值校正），最终得到以海平面为基准的地形高程数据。